What are the main components of the knee joint. How do the bones, muscles, and ligaments work together in knee function. What are common knee conditions and their causes. How does knee anatomy affect movement and stability.

The Fundamental Structure of the Knee Joint

The knee is one of the largest and most intricate joints in the human body, playing a crucial role in mobility and support. Its complex anatomy allows for a wide range of motion while maintaining stability under significant stress. Let’s explore the key components that make up this remarkable joint.

Bones of the Knee

The knee joint is formed by the articulation of three main bones:

• Femur (thigh bone)
• Tibia (shin bone)
• Patella (kneecap)

These bones work together to create two primary joints within the knee structure:

1. The tibiofemoral joint: Where the femur meets the tibia
2. The patellofemoral joint: Where the patella articulates with the femur

What role does the fibula play in knee anatomy? While not directly involved in the knee joint, the fibula, a smaller bone running alongside the tibia, provides attachment points for muscles and ligaments that contribute to knee stability.

Cartilage and Menisci

To facilitate smooth movement and absorb shock, the knee contains specialized cartilage structures:

• Articular cartilage: Covers the ends of the femur and tibia, as well as the back of the patella
• Medial meniscus: C-shaped cartilage on the inner side of the knee
• Lateral meniscus: C-shaped cartilage on the outer side of the knee

How do the menisci contribute to knee function? The menisci act as shock absorbers, distribute weight evenly across the joint, and help stabilize the knee during movement.

Ligaments: The Stabilizers of the Knee

Ligaments are tough, fibrous tissues that connect bones to other bones, providing stability and guiding joint motion. The knee contains four major ligaments:

Cruciate Ligaments

• Anterior Cruciate Ligament (ACL): Prevents the femur from sliding backward on the tibia
• Posterior Cruciate Ligament (PCL): Prevents the femur from sliding forward on the tibia

Collateral Ligaments

• Medial Collateral Ligament (MCL): Stabilizes the inner side of the knee
• Lateral Collateral Ligament (LCL): Stabilizes the outer side of the knee

Why are ligaments crucial for knee stability? These ligaments work together to control the knee’s range of motion and prevent excessive movement in any direction, protecting the joint from injury during physical activities.

Muscles and Tendons: The Power Behind Knee Movement

While not technically part of the knee joint itself, the muscles surrounding the knee play a vital role in its function and stability.

Key Muscle Groups

• Quadriceps: Located on the front of the thigh, these muscles extend the knee
• Hamstrings: Found on the back of the thigh, these muscles flex the knee
• Calf muscles: Help stabilize the knee during weight-bearing activities

How do tendons contribute to knee function? Tendons connect muscles to bones, allowing the transfer of force to create movement. The patellar tendon, which connects the patella to the tibia, is particularly important for knee extension.

Common Knee Conditions and Injuries

The complexity of the knee joint makes it susceptible to various conditions and injuries. Understanding these issues can help in prevention and early intervention.

Degenerative Conditions

• Osteoarthritis: Wear and tear of cartilage, leading to pain and stiffness
• Chondromalacia patella: Irritation of the cartilage under the kneecap

Ligament Injuries

• ACL tear: Often occurs during sudden changes in direction or landing from a jump
• MCL sprain: Typically caused by a blow to the outer part of the knee

Cartilage Injuries

• Meniscal tear: Can result from twisting movements or degenerative changes
• Articular cartilage damage: May occur due to injury or wear over time

What factors increase the risk of knee injuries? Age, obesity, certain sports activities, and occupations requiring repetitive knee stress can all contribute to an increased risk of knee problems.

The Role of Knee Anatomy in Movement and Stability

The intricate design of the knee allows for a remarkable balance between mobility and stability. This joint is essential for various movements:

• Walking and running
• Climbing stairs
• Sitting and standing
• Jumping and landing

How does the knee achieve both flexibility and strength? The combination of bone structure, ligaments, and muscles allows the knee to bear significant weight while also permitting a wide range of motion. The joint can lock into place when extended, providing stability for standing, and can also flex to enable activities like squatting or kneeling.

Biomechanics of the Knee

The knee’s movement is more complex than a simple hinge. It involves a combination of rolling, gliding, and rotation. This complexity allows for efficient movement but also makes the knee vulnerable to injury when subjected to abnormal forces.

How do the different components work together during movement? As the knee flexes and extends, the menisci change shape to maintain contact between the femur and tibia. The cruciate ligaments guide this motion, preventing excessive forward or backward movement of the tibia relative to the femur. Meanwhile, the collateral ligaments provide side-to-side stability.

Diagnostic Techniques for Knee Problems

When knee issues arise, various diagnostic methods can help identify the problem:

• Physical examination
• X-rays
• Magnetic Resonance Imaging (MRI)
• Computed Tomography (CT) scans
• Arthroscopy

Why is a comprehensive diagnostic approach important? Each method provides different information about the knee’s structures. For example, X-rays show bone alignment and potential arthritis, while MRIs can reveal soft tissue injuries like meniscal or ligament tears.

Emerging Diagnostic Technologies

Advancements in medical technology are improving our ability to diagnose and treat knee conditions:

• 3D imaging: Provides detailed views of knee structures
• Ultrasound: Offers real-time imaging of soft tissues
• Biomarker testing: May help identify early signs of conditions like osteoarthritis

Treatment Approaches for Knee Conditions

The treatment of knee problems varies depending on the specific condition and its severity. Options may include:

Conservative Treatments

• Rest and activity modification
• Physical therapy
• Medications (anti-inflammatories, pain relievers)
• Bracing or supportive devices

Surgical Interventions

• Arthroscopic procedures
• Ligament reconstruction
• Partial or total knee replacement

How do healthcare providers determine the best treatment approach? Factors such as the patient’s age, activity level, overall health, and the specific nature of the knee problem all play a role in treatment decisions. Often, a combination of approaches is used to achieve the best outcomes.

Regenerative Medicine

Emerging treatments in the field of regenerative medicine show promise for certain knee conditions:

• Platelet-rich plasma (PRP) injections
• Stem cell therapy
• Tissue engineering for cartilage repair

While these treatments are still being studied, they offer potential alternatives or complements to traditional approaches.

Maintaining Knee Health: Prevention and Lifestyle Factors

Understanding knee anatomy highlights the importance of proactive measures to maintain joint health:

Exercise and Strength Training

Regular exercise can help strengthen the muscles supporting the knee, improving stability and function. Key exercises include:

• Quadriceps strengthening
• Hamstring exercises
• Core stability work
• Low-impact cardiovascular activities

How does exercise benefit knee health? Strong muscles around the knee can help absorb shock, reduce stress on the joint, and improve overall function and stability.

Weight Management

Maintaining a healthy weight is crucial for knee health. Excess weight places additional stress on the knee joint, potentially accelerating wear and tear.

Proper Technique and Equipment

For those involved in sports or physical activities, using proper technique and appropriate equipment can help prevent knee injuries. This includes:

• Wearing appropriate footwear
• Using proper form during exercises
• Gradually increasing activity intensity

Why is technique important in preventing knee injuries? Correct movement patterns distribute forces evenly across the knee joint, reducing the risk of overload on specific structures.

Nutrition for Joint Health

Certain nutrients may support knee health and function:

• Omega-3 fatty acids: May help reduce inflammation
• Vitamin D and calcium: Important for bone health
• Collagen: May support cartilage health

A balanced diet rich in these nutrients, along with overall healthy eating habits, can contribute to long-term knee health.

The human knee is a marvel of biological engineering, allowing us to perform a wide range of movements while supporting our body weight. Its complex anatomy, involving bones, ligaments, cartilage, and muscles, works in harmony to provide both stability and flexibility. Understanding this intricate structure not only helps in appreciating its function but also in recognizing the importance of proper care and maintenance. As medical knowledge and technology advance, our ability to diagnose, treat, and prevent knee problems continues to improve, offering hope for those affected by knee conditions and injuries. By combining this scientific understanding with proactive lifestyle choices, we can work towards maintaining healthy, functional knees throughout our lives.

Knee (Human Anatomy): Function, Parts, Conditions, Treatments

© 2014 WebMD, LLC. All rights reserved.

The knee is one of the largest and most complex joints in the body. The knee joins the thigh bone (femur) to the shin bone (tibia). The smaller bone that runs alongside the tibia (fibula) and the kneecap (patella) are the other bones that make the knee joint.

Tendons connect the knee bones to the leg muscles that move the knee joint. Ligaments join the knee bones and provide stability to the knee:

• The anterior cruciate ligament prevents the femur from sliding backward on the tibia (or the tibia sliding forward on the femur).
• The posterior cruciate ligament prevents the femur from sliding forward on the tibia (or the tibia from sliding backward on the femur).
• The medial and lateral collateral ligaments prevent the femur from sliding side to side.

Two C-shaped pieces of cartilage called the medial and lateral menisci act as shock absorbers between the femur and tibia.

Numerous bursae, or fluid-filled sacs, help the knee move smoothly.

Knee Conditions

• Chondromalacia patella (also called patellofemoral syndrome): Irritation of the cartilage on the underside of the kneecap (patella), causing knee pain. This is a common cause of knee pain in young people.
• Knee osteoarthritis: Osteoarthritis is the most common form of arthritis, and often affects the knees. Caused by aging and wear and tear of cartilage, osteoarthritis symptoms may include knee pain, stiffness, and swelling.
• Knee effusion: Fluid buildup inside the knee, usually from inflammation. Any form of arthritis or injury may cause a knee effusion.
• Meniscal tear: Damage to a meniscus, the cartilage that cushions the knee, often occurs with twisting the knee. Large tears may cause the knee to lock.
• ACL (anterior cruciate ligament) strain or tear: The ACL is responsible for a large part of the knee’s stability. An ACL tear often leads to the knee “giving out,” and may require surgical repair.
• PCL (posterior cruciate ligament) strain or tear: PCL tears can cause pain, swelling, and knee instability. These injuries are less common than ACL tears, and physical therapy (rather than surgery) is usually the best option.
• MCL (medial collateral ligament) strain or tear: This injury may cause pain and possible instability to the inner side of the knee.
• Patellar subluxation: The kneecap slides abnormally or dislocates along the thigh bone during activity. Knee pain around the kneecap results.
• Patellar tendonitis: Inflammation of the tendon connecting the kneecap (patella) to the shin bone. This occurs mostly in athletes from repeated jumping.
• Knee bursitis: Pain, swelling, and warmth in any of the bursae of the knee. Bursitis often occurs from overuse or injury.
• Baker’s cyst: Collection of fluid in the back of the knee. Baker’s cysts usually develop from a persistent effusion as in conditions such as arthritis.
• Rheumatoid arthritis: An autoimmune condition that can cause arthritis in any joint, including the knees. If untreated, rheumatoid arthritis can cause permanent joint damage.
• Gout: A form of arthritis caused by buildup of uric acid crystals in a joint. The knees may be affected, causing episodes of severe pain and swelling.
• Pseudogout: A form of arthritis similar to gout, caused by calcium pyrophosphate crystals depositing in the knee or other joints.
• Septic arthritis: An infection caused by bacteria, a virus, or fungus inside the knee can cause inflammation, pain, swelling, and difficulty moving the knee. Although uncommon, septic arthritis is a serious condition that usually gets worse quickly without treatment.

Anatomy of Knee

Watch This Video of Why Knee Pain Can’t Wait

How Do the Anatomy of Knee and Lower Leg affect Movement?

The knee is a hinge joint that sits between the thigh and the shin. It functions the same as a hinge on a door and sometimes gets a creaky as a hinge can. This joint allows the legs to bend and straighten, necessary for walking, going up and downstairs, going from sitting to standing, running, and jumping. The knee’s anatomy consists of many structures from the bones, tendons, and ligaments to the cartilage and muscles to help the knee function. 

If you want to learn more about knee anatomy, please watch this knee anatomy video or this article Knee JOINT Anatomy.

Anatomy of the Knee Bones and Joints of the Knee Anatomy

The anatomy of the knee consists of 3 main bones:                                         

• The femur (thigh bone).
• The tibia (shin bone).
• The patella (knee cap).

Lateral Knee Anatomy

The femur and the tibia are the main movers of the joint to allow for the hinge motion.  This connection of the femur and tibia is a joint called the tibiofemoral joint. The patella sits on top of the tibiofemoral joint in a groove in the front of the femur. The patella is a floating bone that works as a fulcrum for the quadriceps muscle (you will read about this later) to function properly.  This joint is called the patellofemoral joint and allows the patella to move up and down, and the knee bends and straightens.  

Ligaments and Tendons of the Knee

The knee has 4 main ligaments:

• Medial collateral ligament (MCL): On the inside of the knee closer to the midline.
• Lateral collateral ligament (LCL): Is on the outside of the knee.
• An anterior cruciate ligament (ACL): Inside of the knee and crosses to the front.
• A posterior cruciate ligament (PCL): Inside of the knee and crosses to the back.

The MCL and the LCL sit on the sides of the knee, and they help give stability to the knee if your knee gets hit from the sides. Knee bones, ligaments, and meniscus

The ACL and PCL are inside the knee and cross each other as they run front to back and vise versa. These 2 ligaments are responsible for giving the knee stability from front to back. 

An ACL injury is probably one of the most recognized injuries in sports and, most of the time, requires a surgical repair that has a long recovery time. A full recovery after an ACL reconstruction is usually between 6 to 9 months depending on the patient and the other structures injured.   

The unhappy triad is referred to when the ACL, MCL and Medial Meniscus are all injured at the same time. .

Tendons are where muscles attach to the bones of the knee.  There are numerous tendons in the knee.  The tendons which are prone to injuries of the knee are the Patellar Tendon and the Quadriceps Tendon.  These patellar tendons can rupture or tear and they can also get tendonditis.

Cartilage Of The Knee Joint

There are two main types of cartilage in knee anatomy: articular cartilage and the meniscus. 

• Articular cartilage covers the bones’ ends and allows for the bones to slide and glide on each other without friction. This is the stuff you need to keep from getting the creaking and cracking of the joints. When this starts to wear down, arthritis will set in.  Sometimes this cartilage is damaged with an ACL tear.  The amount of trauma from the ACL injury can lesions to the cartilage of the joint or bones of the knee. This can be addressed during the surgical procedure.

Image of articular cartilage and meniscus

• Meniscus: 2 thick pieces of cartilage that sit on the tibia between the femur and tibia. These are C-shaped that allow for improved congruence of the joint. Tears in these structures can cause pain, swelling, and sometimes catching and locking the knee joint.  During surgery, the meniscus can be repaired or debrided.  This is usually determined by the age of the patient, where the tear occurred and the amount of damage to the meniscus. To learn more, Read this Article about Meniscus Injuries.

What are the Symptoms of a Torn Ligament in the Knee?

The quick answer is that a torn knee ligament can cause:

• Pain and the inability to walk
• Significant Swelling
• Feeling a “pop”
• Instability or loose feeling in the knee
• In sports, the athlete’s leg gives way during the sport.

To learn more, check out this article on Knee Ligaments.

Muscles and Tendons of the Knee 

Many muscles affect the knee, but the main muscles that allow for the knee to perform its main functions are:

• Quadriceps: A group of 4 muscles that sits on the front of the thigh. These muscles are responsible for allowing the knee to straighten. This movement is necessary for standing from a seated position, bringing your leg forward when walking, and kicking a ball!  The two patellar tendons attach the quad to the patella.  These tendons can also rupture during sports. 

Quadriceps Muscle diagram

• Hamstrings: A group of 3 muscles sits at the back of the thigh and allows for the knee to bend.  These muscles are responsible for lifting your foot to walk.  The hamstring muscles can be strained or torn during sport activities.  The athlete is described by “pulling up” while running.  This is a classic sign of a hamstring strain. 

Hamstring Muscle diagram

• Gastrocs: A group of 2 muscles that sit in on the lower leg backside that works in tandem with the hamstrings to cause the knee to bend.  The gastroc or calf muscle can be strained and torn during sports like tennis or basketball.  The athlete will feel a “pop’ in the calf.  

Calf Muscle Diagram

• Tendons attach the knee muscles to the bone.  The two patellar tendons can also be prone to overuse and the development of patellar tendonitis.  Jumper’s knee is common in the knee with athletics. 

All of these muscles also have functions at different joints such as the hip and the ankle. Injuries to these structures, such as a pull or strain, will cause pain when activating the muscle and, if severe enough, will cause significant weakness.

Knee Doctors in Jacksonville

Many types of knee injuries can occur. Muscles, tendons, ligaments, and cartilage can be strained and sprained. It is really important to have your knee pain properly diagnosed by an orthopedic physician. JOI Rehab also has 12 Physical Therapy locations, which can certainly help you on the road to recovery. With over 90 Rehab Clinicians trained in providing you with the highest quality of orthopedic care.  For an appointment, please call 904-858-7045.

If you want to learn more about a torn ACL, go to Torn ACL or go to Knee Ligaments Article.

The Jacksonville Orthopaedic Institute will continue to monitor the latest developments of coronavirus disease (COVID-19), we are committed to protecting the health and safety of our patients, families and caregivers. To read more about our safety measures go to JOI4U. JOI & JOI Rehab, encourages all patients to wear a mask to their appointment. Anyone with COVID-19 symptoms, including fever, cough or shortness of breath, should contact 904-JOI-2000 prior to your scheduled appointment. In an effort to adhere to the national social distancing request, please do not bring family members to your appointment unless they are needed for translation or transportation.  You can also complete all of your new patient paperwork from home. To request registration paperwork electronically click HERE.

JOI Fracture and Injury Care

JOI MD’s now offer quick fracture care. Make an appointment by calling (904)JOI-2000, schedule online, or click the link below…

By Katie Trumble DPT/ATC

Knee Anatomy Video | Medical Video Library

The knee is a complex joint made up of different structures including bones, tendons, ligaments and muscles. They all work together to maintain normal function and provide stability to the knee during movement.

Having a well-functioning healthy knee is essential for our mobility and ability to participate in various activities. Understanding the anatomy of the knee enhances your ability to discuss and choose the right treatment procedure for knee problems with your doctor.

Bones.

The Knee is a hinge joint made up of two bones, the thigh bone (femur) and the shinbone (tibia). There are two round knobs at the end of the femur called femoral condyles which articulate with the flat surface of the tibia called the tibial plateau. The tibia plateau on the inside of the leg is called the medial tibial plateau, and on the outside of the leg it is called the lateral tibial plateau.

The two femoral condyles form a groove on the front (anterior) side of the knee called the patellofemoral groove. A small bone called the patella sits in this groove and forms the knee cap. It acts as a shield and protects the knee joint from direct trauma.

A fourth bone called the fibula is the other bone of the lower leg. This forms a small joint with the tibia. This joint has very little movement and is not considered a part of the main joint of the knee.

Articular Cartilage and Menisci.

Movement of the bones causes friction between the articulating surfaces. To reduce this friction, all articulating surfaces involved in movement are covered with a white, shiny, slippery layer called articular cartilage. The articulating surface of the femoral condyles, tibial plateaus and the back of the patella are covered with this cartilage. The cartilage provides a smooth surface that facilitates easy movement.

To further reduce friction between the articulating surfaces of the bones, the knee joint is lined by a synovial membrane which produces a thick clear fluid called synovial fluid. This fluid lubricates and nourishes the cartilage and bones inside the joint capsule.

Within the knee joint between the femur and tibia there are two C shaped cartilaginous structures called menisci. Menisci function to provide stability to the knee by spreading the weight of the upper body across the whole surface of the tibial plateau. The menisci help in load bearing by preventing the weight from concentrating onto a small area, which could damage the articular cartilage. The menisci also act as a cushion between the femur and tibia by absorbing the shock produced by activities such as walking, running and jumping.

Ligaments.

Ligaments are tough bands of tissue that connect one bone to another bone. The ligaments of the nee function to stabilize the knee joint. There are two important groups of ligaments that hold the bones of the knee joint together, collateral ligaments and the cruciate ligaments.

Collateral ligaments are present on either side of the knee. They function to prevent the knee from moving too far during side to side motion. The collateral ligament on the inside is called the medial collateral ligament (MCL) and the collateral ligament on the outside is called the lateral collateral ligament (LCL).

Cruciate ligaments- This group of ligaments, present inside the knee joint, control the back and forth motion of the knee. The Cruciate ligament in the front of the knee is called anterior cruciate ligament or ACL and the cruciate ligament in the back of the knee is called posterior cruciate ligament or PCL.

Muscles.

Muscles: There are two major muscles, the quadriceps and the hamstrings, which enable movement of the knee joint. The quadriceps muscles are located in the front of the thigh. When the quadriceps muscles contract, the knee straightens. The hamstrings are located in the back of the thigh. When the hamstring muscles contract, the knee bends.

Tendons.

Tendons are structures that attach muscles to the bone. The quadriceps muscles of the knee meet just above the patella and attach to it through a tendon called the quadriceps tendon. The patella further attaches to the tibia through a tendon called the patella tendon. The quadriceps muscle, quadriceps tendon and patellar tendon all work together to straighten the knee. Similarly, the hamstring muscles at the back of the leg are attached to the knee joint with the hamstring tendon.

The knee is a complex joint with many different parts that function together to allow movement and provide support to the body’s full weight when standing, walking and running.

Knee Anatomy

The knee joint is the largest joint in the human body, and the joint most commonly affected by arthritis. Knowing about knee anatomy can help people understand how knee arthritis develops and sometimes causes pain.

See Possible Causes of Severe Knee Pain

The knee joint is a hinge joint, meaning it allows the leg to extend and bend back and forth with minimal side-to-side motion. It is comprised of bones, cartilage, ligaments, tendons, and other tissues.

Bones of the Knee

Save

Three bones meet and move against each other at the knee joint:

• The bottom of the femur (thigh bone) meets with top of the tibia (shin bone)
• The patella (kneecap) glides along a grove located at the bottom and front of the femur

Bones and arthritis: One sign of arthritis is the development of osteophytes, or bone spurs, at the joint. These small growths on bones can create friction and affect a knee’s range of motion.

See Osteoarthritis Symptoms and Signs

advertisement

Articular Cartilage of the Knee

Save

Articular cartilage covers the surfaces of the bones where they meet: at the bottom of the femur, the top of the tibia, and the back of the kneecap. Articular cartilage is an extremely slippery, strong, flexible material.

See What Is Cartilage?

Articular cartilage serves two purposes:

• It allows the bones to glide over each other as the knee bends and straightens
• It acts as a shock absorber, cushioning bones against impacting each other (e.g. during walking)

Cartilage and arthritis: Knee arthritis is defined by the loss of healthy articular cartilage in the knee.

See What Is Knee Osteoarthritis?

Knee Meniscus

Save

A knee meniscus is a thick pad of cartilage located between the femur and tibia. There are two menisci in each knee:

• The medial meniscus, which is located on the inside of the knee.
• The lateral meniscus, located on the outer side of the knee.

The menisci reduce shock and absorb impact when the knee is moving or bearing weight. They also help stabilize the knee and facilitate smooth motion between the surfaces of the knee.

Knee meniscus and arthritis: A meniscus injury or meniscus degeneration can lead to the wear-and-tear of articular cartilage, and vice versa.

See Understanding Meniscus Tears on Sports-health.com

Ligaments of the Knee

Save

Ligaments are bands of strong tissue that connect bone to bone. The knee has 4 major ligaments that connect the femur to the tibia:

• Anterior cruciate ligament (ACL)
• Posterior cruciate ligament (PCL)
• Medial collateral ligament (MCL)
• Lateral collateral ligament (LCL)

The ACL and PCL prevent the femur and tibia from sliding too far forward or backward. The MCL and LCL prevent side to side movement.

A relatively new discovery revealed another ligament in the knee that was named antero lateral ligament (ALL), which seems to work in conjunction with ACL.¹ However, research is still ongoing to clarify its exact job and importance to the function and stability of the knee.

Ligaments and knee arthritis: Knee ligament injuries can lead to joint instability, accelerating the wear-and-tear that leads to knee arthritis. Conversely, knee arthritis can cause joint instability, which puts more strain on ligaments and increases the risk of ligament injuries.

Read more about Anterior Cruciate Ligament (ACL) Injuries on Sports-health.com

Tendons of the Knee

Save

Tendon tissue connects bone to muscle. The knee’s largest tendon is the patellar tendon.

The patella tendon begins at the thigh’s quadriceps muscles and extends downward, attaching patella to the front of the tibia. When the quadriceps muscles contract the patellar tendon is pulled and the leg straightens.

Tendons and arthritis: Patellar tendon problems can arise from knee arthritis but are more likely to affect athletes who do a lot of running, pivoting, and jumping. If the patellar tendon becomes irritated and inflamed it is called patellar tendinopathy, also known as jumper’s knee.

See Understanding Jumper’s Knee on Sports-health.com

Bursae Surrounding the Knee

Save

A bursa is a tiny, slippery, fluid-filled sac located between a bone and soft tissue. Like cartilage, bursae reduce friction. But while cartilage reduces friction between bones, bursae reduce friction between bones and soft tissues, such as muscles and tendons—the bursae help muscles and tendons slide freely as the knee joints move. The knee has several bursae.

See What Is a Bursa?

Bursae and knee arthritis: Arthritis can alter joint biomechanics, leading to irritation of a bursa. When a bursa is irritated and inflamed, it is called bursitis. The most common form of knee bursitis is prepatellar bursitis.

See Knee (Prepatellar) Bursitis

The Knee’s Synovial Membrane and Synovial Fluid

Save

A delicate, thin membrane, called the synovial membrane, encapsulates the knee joint. The synovial membrane produces synovial fluid. This viscous fluid lubricates and circulates nutrients to the joint.

• When the knee is at rest, the synovial fluid is contained in the cartilage, much like water in a sponge.
• When the knee bends or bears weight the synovial fluid is squeezed out. Therefore, joint use is necessary to keep joints lubricated and healthy.

See What Is a Synovial Joint?

The synovial membrane, synovial fluid, and knee arthritis: If the synovial membrane becomes inflamed, it is called synovitis. People who have rheumatoid arthritis and other inflammatory joint conditions may experience synovitis. In addition, a knee affected by osteoarthritis may have too little synovial fluid, exacerbating joint friction.

See How Do Synovial Joints Work?

advertisement

Muscles of the Knee

Save

For a knee joint to maintain its normal range of motion, the surrounding muscles must be flexible. The muscles must also be strong to provide adequate support to the knee joint.

• Quadriceps muscles at front of the thigh
• Hamstrings at the back of the thigh
• Lower leg muscles, including the gastrocnemius at the back of the calf

Muscles and knee arthritis: Weak muscles will not provide adequate support and stability; therefore, weak muscles can lead to or accelerate knee osteoarthritis.

In addition, recent studies suggest that arthritis may trigger mechanisms that make the surrounding muscles of the knee weaker, creating a cycle where weakness promotes arthritis and arthritis promotes further weakness.^2–4 This information makes proper knee support exercises in the context of arthritis even more important.

See Knee Exercises for Arthritis

The knee is a large, complex joint with many parts. When one part is injured or degenerates, it can change the knee joint’s biomechanics and have a cascading effect on other parts. The best way to avoid joint degeneration and knee osteoarthritis is to eat a healthy diet, maintain a normal weight, and participate in a routine exercise program.

References

• 1.Farhan PHS, Sudhakaran R, Thilak J. Solving the Mystery of the Antero Lateral Ligament. J Clin Diagn Res. 2017;11(3):AC01-AC04.
• 2.Silva JMS, Alabarse PVG, Teixeira VON, et al. Muscle wasting in osteoarthritis model induced by anterior cruciate ligament transection. PLoS One. 2018;13(4):e0196682. Published 2018 Apr 30. doi:10.1371/journal.pone.019668
• 3.Silva J, Alabarse P, Teixeira V, et al FRI0768-HPR Muscle wasting in osteoarthritis model induced by anterior cruciate ligament transection Annals of the Rheumatic Diseases 2017;76:1508.
• 4.Alnahdi AH, Zeni JA, Snyder-Mackler L. Muscle impairments in patients with knee osteoarthritis. Sports Health. 2012;4(4):284-92

Knee Anatomy

The following article will provide knee anatomy information for patients and their families.

The largest joint in the body, the knee is also one of the most complex. The knee may be described as a modified hinge joint, similar to the hinge on a door. However, the knee not only bends back and forth like a hinge, it has a complex rotational component that occurs with flexion and extension of the knee.

The knee is a major weight-bearing joint that is held together by muscles, ligaments, and other important soft tissue. Cartilage is the material inside the joint that provides shock absorption to the knee during weight-bearing activities such as walking or stair climbing.

Below is an illustration of knee anatomy with its major bones, ligaments and muscles appropriately labeled.

Knee Anatomy: Bones
The bones of the knee are the femur (thigh bone), tibia (shin bone) and patella (kneecap). The femur and tibia meet to form a hinge with the patella in front of these two bones protecting the joint. The patella slides up and down in a groove in the femur (the femoral groove) as the knee is bent and straightened.

Knee Anatomy: Ligaments
Ligaments hold the knee together and give it stability. The medial (inner) collateral ligament (MCL) and outer (lateral) collateral ligament (LCL) limit sideways motion of the knee. The posterior and anterior cruciate ligaments (PCL and ACL) limit forward motion of the knee bones, keeping them stable.

Knee Anatomy: Cartilage
Two structures known as menisci sit between the femur and the tibia and act as cushions or shock absorbers for the knee. A torn meniscus is often referred to as torn cartilage. Menisci are one of two types of cartilage in the knee. The other type, articular cartilage, is a smooth and very slick material that covers the end of the femur, the femoral groove, the top of the tibia and the underside of the patella. This articular cartilage allows the bones to move smoothly.

Knee Anatomy: Tendons
Tendons connect muscle to knee. The quadriceps muscles on the front of the thigh are connected to the top of the patella by the quadriceps tendon, which covers the patella and becomes the patellar tendon. The patellar tendon then attaches to the front of the tibia. The hamstring muscles in the back of the leg attach to the tibia at the back of the knee. The quadriceps muscles straighten the knee and the hamstring muscles bend the knee.

Bones, ligaments, cartilage and tendons all work together to build a healthy knee.

Click on the image below to view an interactive animation of knee anatomy.

(136k – Requires:
Requires Free Flash Player, Download Here)

Bones, Ligaments, Muscles, Tendons, Function

The knee joint is a synovial joint which connects the femur (thigh bone), the longest bone in the body, to the tibia (shin bone).  There are two main joints in the knee: 1) the tibiofemoral joint where the tibia meet the femur 2) the patellofemoral joint where the kneecap (or patella) meets the femur. These two joints work together to form a modified hinge joint that allows the knee to bend and straighten but also to rotate slightly from side to side.

The knee joint is the largest joint in our body. It is vulnerable to injury as it bears an enormous amount of pressure while providing flexible movement. When we walk, the load on our knees is equal to 1.5 times our body weight. When climbing stairs it is equal to 3-4 times our body weight.  When we squat, the load on our knees increases to about 8 times our body weight!

Anatomical terms allow us to describe the body and body motions more precisely. Instead of a doctor simply saying that “the patient’s knee hurts”,  he or she can say that “the patient’s knee hurts anterolaterally” to specify where exactly in the knee you are having pain.  Identifying specific areas of pain helps to guide the next steps in treatment or work-up. Below are some anatomic terms doctors use to describe location (as applied to the knee):

• Anterior — if facing the knee, this is the front of the knee
• Posterior — if facing the knee, this is the back of the knee. If used to describe the patella (knee cap), then it would refer to the side of the patella closest to the femur.
• Medial — the side of the knee that is closest to the other knee, if you put your knees together, the medial sides of each knee would touch
• Lateral — the side of the knee that is farthest from the other knee (opposite of the medial side)
• Abduction — move away from the body (raising the leg away from midline i.e. towards the side)
• Adduction — move toward the body (lowering the leg toward midline i.e. from the side)
• Proximal — located nearest to the point of attachment or reference, or center of the body
  • example: the knee is proximal to the ankle
• Distal — located farthest from the point of attachment or reference, or center of the body
  • example: the ankle is distal to the knee
• Inferior — located beneath, under or below
• Superior – located above

Structures often have their anatomical reference as part of their name, particularly if there are other similar structures close by. For instance, there are two menisci (or meniscus, singular) in the knee. As such, they are named the medial meniscus and lateral meniscus. Therefore, the medial meniscus would refer to the meniscus on the inside of the knee (i.e. closest to the other knee).

Structures of the Knee

Again, the knee joint is a hinge type joint. The part of the door that keeps it secured to the wall and allows it to open and close is called a hinge. The majority of the movement allowed by the knee is the same type of motion allowed by a door hinge. It additionally allows for a small amount of rotational movement.

If you think of the knee in layers, the deepest layer is bone and ligaments, then ligaments of the joint capsule, then muscles on top. Various nerves and blood vessels supply the muscles and bones of the knee.

Bones of the Knee

There are four bones around the knee: the thigh bone (femur), the shin bone (tibia), knee cap (patella), and the fibula (see image to the left):

• Femur (thigh bone) – the longest bone in the body;  The round knobs at the end of the bone (near the knee) are called condyles. Within the knee joint, the end of the femur is covered in hyaline (or articular) cartilage.
• Tibia (shin bone) –  runs from the knee to the ankle. The top of the tibia is made up of two plateaus (or flat surfaces) which are covered in articular cartilage (within the knee joint). Attached here are two C-shaped shock-absorbing cartilages called menisci. A knuckle-like protuberance on the front (or anterior aspect) of the knee is called the tibial tubercle. The patellar ligament (or tendon) attaches here (see below).
• Patella (kneecap) – a semi-flat, triangular bone that is able to move as the knee bends. It’s main function is to increase the force generated by the quadriceps muscle (which straightens or extends the knee). For instance, if you break (or fracture) the patella, the quadriceps may not be able to effectively pull on the tibia and you may not be able to straighten your knee. This is one of the main reasons why patellar fractures often need to be fixed. The patella also protects the knee joint from trauma. The patella glides within the groove formed between the two femoral condyles called the patellofemoral groove.
• Fibula— a long, thin bone in the lower leg on the lateral side which runs along side the tibia from the knee to the ankle. While about 80-90% of weight is carried by the tibia, the fibula does help to carry some weight as well. Importantly, it serves as an attachment for muscles like the biceps femoris (one of the hamstring muscles), lateral collateral ligament (see below), and also helps to form the ankle joint.

Ligaments in the knee

Ligaments are strong, tough bands that are not particularly flexible. The function of ligaments is to attach bones to bones and to help keep them stable. In the knee, they give stability and strength to the knee joint as the bones and cartilage of the knee have very little stability on their own.

• Medial Collateral Ligament (or the tibial collateral ligament) – attaches the medial side of the femur to the medial side of the tibia and limits sideways motion of your knee.
• Lateral Collateral Ligament (or the fibular collateral ligament) – attaches the lateral side of the femur to the lateral side of the fibula and also limits sideways motion of your knee.
• Anterior cruciate ligament (ACL) – attaches the tibia and the femur. It’s located deep inside the knee and in front of the posterior cruciate ligament. It mainly serves to limit forward motion of the tibia relative to the femur. It also limits some rotation and sideways motion of the knee. The ACL can be torn with sudden pivoting motions of the knee.
• Posterior cruciate ligament (PCL) – like the ACL, it attaches the tibia and the femur. It lies behind the anterior cruciate ligament. It mainly limits backward motion of the tibia relative to the femur. Like the ACL, it also limits some rotation and sideways motion of the knee. The PCL can be torn with a forceful landing on the shin.
• Patellar ligament (or tendon) – attaches the kneecap to the tibia. It is less of ligament and actually a continuation of the quadriceps tendon.
• Joint Capsule – a thick, fibrous structure that wraps around the knee joint. Inside the capsule is the synovial membrane which is lined by the synovium, a soft tissue structure that secretes synovial fluid, the lubricanr of the knee.

The pair of collateral ligaments keeps the knee from moving too far side-to-side. The cruciate ligaments crisscross each other in the center of the knee. They allow the tibia to “swing” back and forth under the femur without the tibia sliding too far forward or backward under the femur. Working together, the 4 ligaments are the most important in structures in controlling stability of the knee.

Cartilage of the Knee

There are many types of cartilage in our body, each with a slightly different function. For instance, the medial and lateral meniscus (discussed below) are made up of fibrocartilage which make them strong and rubbery and able to add additional stability to the knee.   On the other hand, like bones of most joints, the end of the femur and tibia and the undersurface of the patella are covered in hyaline cartilage. Hyaline (also known as articular) cartilage is both flexible and slippery. The flexibility helps it to act as a shock absorber. Articular cartilage is made even more slippery by an oily lubricant made within the joint, called synovial fluid. This allows the two bones to move smoothly on each other without pain. If this articular cartilage wears away, joint movement can become painful and limited (this is known as arthritis). Unfortunately, cartilage has almost no blood supply and is very bad at repairing itself.

• Medial Meniscus

  The medial meniscus is a crescent shaped structure that exists on the inside of the knee. It is made of fibrocartilage. It acts as a shock absorber in the knee and adds stability to the knee joint.  It is attached to the tibia as well as to the joint capsule of the knee.

• Lateral Meniscus

  The lateral meniscus sits on the lateral tibial plateau. It is a crescent shaped structure that is also made up of fibrocartilage. It acts as a shock absorber in the knee and adds stability to the knee joint.  It is attached to the joint capsule of the knee as well.  It is somewhat more mobile than the medial meniscus.

In a healthy knee, the rubbery menisci act as shock absorbers. They both sit on top of the tibia and help to spread the load of the femur over a larger surface area on the tibia. If the menisci are removed (because they are torn, etc.) the underlying articular cartilage sees a heavier load and is at risk of wearing down faster (i.e. development of osteoarthritis)

Additionally, together, the menisci create a shallow socket on the tibia that accommodates the end of the femur. This assists with knee stability.

Muscles Around the Knee

The muscles around the knee help to keep the knee stable, well aligned, and moving. There are two main muscle groups around the knee: the quadriceps and the hamstrings. The quadriceps are a collection of 4 muscles on the front of the thigh and are responsible for straightening the knee by bringing a bent knee to a straightened position. The hamstrings are a group of 3 muscles on the back of the thigh that provide the opposite motion by bending the knee from a straightened position.

The iliotibial band is a broad tendinous extension of the tensor fascia lata and gluteus maximus that also helps to stabilize the knee.

Tendons in the Knee

Tendons are elastic tissues made up of collagen. They are the continuations of muscles and allow them to connect to bones. There are numerous tendons around the knee that also help to stabilize the knee. They are associated with muscles discussed in the section above (see above).  One of the most important tendons is the quadriceps tendon. This lies on the front of the knee and connects the quadriceps muscles of the thigh to the tibia via the patella and patellar ligament (or tendon). It provides the power necessary to straighten the knee.

Bursae

There are up to 13 bursa of various sizes in and around the knee. These fluid filled sacs cushion the joint and reduce friction between muscles, bones, tendons and ligaments. There are bursa located underneath the tendons and ligaments on both the lateral and medial sides of the knee. The prepatellar bursa is one of the larger bursae of the knee and is located on the front of the patella (hence pre-patellar) just under the skin. It protects the patella. Sometimes, whether due to direct trauma or even infection, it can become irritated, swollen, and painful.  This is known as prepatellar bursitis.

The pes bursa is another important bursa that overlies some of the hamstring tendons which attach to the medial side of the tibia.  It too can sometimes become irritated, causing pes bursitis, which can be painful.

Plicae

Plicae are folds in the synovium within the knee joint itself. Plicae rarely cause problems but sometimes can get caught between the femur and patella and cause pain.

Knee Arteries and Veins

Probably the most important thing to know about the blood supply to the knee is that it is very abundant. There are many collateral vessels (basically extra vessels) that give blood supply to the structures of the knee.

Knee arteries and veins

Problems in the Knee

As the knee has many structures associated with it, there are many problems that can occur around the knee.  In addition to wear and tear type issues of the knee, sports injuries are the source of many knee problems.

Symptoms

Knee symptoms can be quite variable. Pain can be dull, sharp, constant or an on-and-off type pain. As there are many structures of the knee that are prone to injury, depending on the underlying problem, the location of pain can be variable as well.

With certain types of injuries (ligamentous injuries), knee range of motion may actually increase as the knee becomes unstable.  On the other hand, with arthritis of the knee, range of motion can decrease.

Depending on the injury, you may experience “mechanical symptoms”. Mechanical symptoms are ones that affect the normal function of the knee.  Catching or locking of the knee, whether painful or painless, are examples of mechanical symptoms (see below). Additionally, you may hear grinding or popping (crepitus).

• Swelling
• One of the most common symptoms associated with knee problems is local swelling. The accumulation of too much synovial fluid (synovial effusion) is usually due to irritation or inflammation of structures within the joint.  Bleeding into the joint (called a hemarthrosis) can also cause a joint to swell. Swelling immediately following an injury is usually from bleeding. More delayed swelling or on-and-off swelling are usually from excess synovial fluid production from an irritated knee.  The best initial home therapy for swelling is R.I.C.E. therapy.

• Chronic swelling can start to limit full range of motion. This may eventually lead to muscle atrophy (or wasting) from non-use of the muscles around the knee.

• Locking (or Catching)

  Locking or catching of the knee usually occurs when there is a loose body or a torn meniscus in the knee. The loose body can be as small as a grain of sand or as big as a quarter. It is usually a piece of cartilage that has been chipped off of the end of the femur or tibia or a piece of torn meniscus that has become free.  As it floats around the knee, it can suddenly limit normal motion and be associated with significant pain. A torn flap of meniscus (that is still attached) can do the same thing. If the symptoms are bad enough, knee arthroscopy may be needed to address the issue.

• Giving Way

  Sometimes, depending on the underlying problem, your knee may occasionally feel unstable and you may feel like you’ve momentarily lost control of the muscles around the knee. This may cause you to stumble or even fall. There are many reasons why this can occur, including injuries to ligaments. Sudden sharp pains in the knee from a loose body or a torn meniscus can also cause your knee to reflexively feel weak and give way.

• Snaps, Crackles and Pops

  Popping or crackling noises – medically termed crepitus – coming from the knee without any associated pain are oftentimes normal. However, If you have pain, swelling or loss of knee function, you should seek the opinion of an orthopedic surgeon. The most common causes of crepitus are osteoarthritis and a condition called —chondromalacia patella—where the cartilage under the patella starts to wear down. These conditions result in rough surfaces within the knee that rub on each other and cause noise (i.e. crepitus).

If your symptoms are interfering with your quality of life, you should see an orthopedic surgeon to have your knee evaluated. He or she will perform a history (ask you questions about your symptoms and how they started) and a physical exam.   Imaging studies then may be ordered to help figure out what is causing your symptoms.  If you have had imaging studies performed elsewhere, it is always best to bring the actual CD of the study (i.e. not just the report) to your surgeon so that they can actually look at it in person. This will speed up the time it takes to figure out how to best treat your problem. 

Pathological Conditions and Syndromes in the Knee

Types of Knee Surgery

Note that the information in this article is purely informative and should never be used in place of the advice of professionals.

Knee Anatomy

The knee anatomy is a complex hinge joint that flexes, extends, and twists slightly from side to side. It is responsible for weight bearing and movement. The knee consists of bones, meniscus, ligaments, and tendons.

• The knee is the meeting point of the femur (thigh bone) in the upper leg and the tibia (shinbone) in the lower leg.
• The fibula (calf bone), the other bone in the lower leg, is connected to the joint but is not directly affected by the hinge joint action.
• The patella (kneecap), is at the center of the knee.
• The meniscus is sometimes called cartilage, and the knee has two: the medial (inner) and lateral (outer). These crescent-shaped discs are tough and rubbery, and act as a cushion or ‘shock absorber’ between the femur and tibia so that the bones of the knee can move through their range of motion without rubbing against each other.

Four Ligaments of the Knee

Ligaments of the knee act like strong ropes to connect bones to other bones. The stability of the knee joint depends on the following four ligaments.

1. Anterior cruciate ligament (ACL)
2. Posterior cruciate ligament (PCL)
3. Medial collateral ligament (MCL)
4. Lateral collateral ligament (LCL)

Cruciate Ligaments are found inside the knee joint. They cross each other to form an “X” with the anterior cruciate ligament (ACL) in front and the posterior cruciate ligament (PCL) in back. The cruciate ligaments control the back and forth motion of your knee.

Collateral Ligaments are found on the sides of your knee. The medial collateral ligament (MCL) is on the inside and the lateral collateral ligament (LCL) is on the outside. These two ligaments control the sideways motion of the knee and brace it against unusual movement.

Bursae of the Knee

Knee bursae are fluid sacs filled with synovial fluid encompassing the bone joint that will sometimes communicate with the joint cavity. They are found all over the body between muscles and bone and function to reduce friction and act like a cushion which allows for allows everything to move smoothly preventing inflammation.

Two Types of Bursae

1. Communicating
2. Non-communicating Bursae 

Five Main Knee Bursae Based on Location (Total of 14 Knee Bursae)

1. Prepatellar Bursa: Anterior bursae over the kneecap. Inflammation can occur with prolonged kneeling as in trades such as roofers and carpet fitters.
2. Infrapatellar Bursa: Two anterior bursae called deep and superficial infrapatellar bursae underneath the kneecap protecting the patellar tendon
3. Suprapatellar  Bursa: Anterior bursa above the kneecap underneath the quadriceps tendon at the bottom of the thigh preventing friction from the femur.
4. Pes Anserine Bursa: Anterior bursa on the medial (inner side) of the knee two inches below the joint between the medial collateral ligament and tendons of the muscles sartorius, gracilis and semitendinosis. Not uncommonly, runners can develop inflammation of Pes Anserine.
5. Semimembranosus Bursa: is found at the back of the knee between the hamstring muscles (semimembranosus muscle) and the inner calf muscles (medial head of gastrocnemius). A Bakers Cyst is inflammation of the Semimembranosus Bursa that results in a soft mass at the back of the knee, which may occur with arthritis.

Tendons of the Knee

Tendons of the knee are tough bands of tissue which connect muscles to bone and provide stability to the joint.

Muscles of the Knee

Muscles around the knee, while not part of the knee anatomy per se, the hamstrings and quadriceps are the muscles that strengthen the leg and help flex the knee.

• Quadriceps femorus muscle group (rectus femoris, vastus lateralis, vastus medius, and vastus intermedius) crosses the knee via the patella and acts to extend the leg.
• Hamstring muscles (semitendinosus, semimembranosus, and biceps femoris) flex the knee and extend the hip (except for the short head of the biceps femoris).
• Popliteus muscle at the back of the leg unlocks the knee by rotating the femur on the tibia, allowing flexion of the knee.

Learn about the Types and Causes of Common Knee Injuries and Problems

1. Types and causes of Knee Injuries and Problems
2. Knee Anatomy
3. Knee Pain and Injury Symptoms and signs
4. When to Call your Doctor
5. Treatment for Common Knee Injuries and Problems
6. Ice or Heat for An Injury?
7. Meniscus Tear
8. Preventing Knee Injuries
9. Knee Replacement

Our goal at OSMI is to provide our patients quality, cutting-edge orthopedic treatments, both surgical and non-surgical.  If you have questions about knee arthroscopy or surgery, knee joint pain, or physical therapy, please submit an online appointment request or contact our office at 817-529-1900.

Knee Anatomy, Knee Physiology

Knee Anatomy

Of all the elements of the musculoskeletal system of the human body, the knee is the largest joint. Its anatomy and physiology of movement are complex.

Anatomical features

It is formed by three large bones:

• femur, attached to the articular tissue at its distal end;
• tibia, proximal to the knee;
• patella.

Knee joints: femoral-patellar and femoral-tibial. The knee is a unique element of the human body, the range of motion of which runs in three planes. Flexion and extension movements of the knee take place in the sagittal plane.

In the frontal plane, movements such as adduction and abduction of the joint occur. The horizontal plane is the flexed joint. The knee can slide and roll, it is possible to perform these movements due to the involvement of the tibia and peroneal femur in its activity.

The possibility of the simultaneous position of the knee in three planes explains the complexity of the knee biomechanics. When the joint is extended to form a 90 to 180 ° angle, the tibia shifts into anterior rotation. In this case, the condyles of the femur and tibia are in a non-congruent state.

Thanks to this position, the knee joint moves freely, nothing limits the wide range of joint movements. Active movements of the joint can cause it to shift to the side, but this does not happen due to the presence of soft tissue structures in the knee.These are menisci, ligaments and muscles. All of them are intertwined with each other and form a powerful ligamentous and tendon apparatus, which fixes the joint in a static position and prevents its displacement.

Menisci – the components of the knee, represented by cartilaginous tissue. They act as a spacer between all surfaces of the joint so that they move without excessive friction. Since the tibia and femur are not congruent in the knee joint, that is, disproportionate, there must be something that compensates for their disparity, and menisci perform this function.

Cartilage pads have a connection with the articular capsule through the ligaments of the femur and tibia. Coronary ligaments, which belong to the tibia, have the strongest fibers. All menisci of the knee interact with each other through cruciate ligaments, anterior and posterior.

The edges of the menisci are free, they have no connection with the knee joint and are devoid of blood vessels. In the musculoskeletal system of a person over the age of 20, only the periphery of the knee joint is equipped with a mesh of blood vessels.

A unique component of the knee – cruciate ligaments, anterior and posterior. They are located directly in the joint, separated from the main knee cavity by the membrane of the synovial bursa. Cruciate ligaments have a thickness of 10 mm, the length of each of them is up to 35 mm.

Structure – at first the ligament is as wide as possible, narrows downward. The cruciate ligament is attached to the tibia through the condyle. The anterior and posterior cruciate ligaments are composed of very strong fibers containing large amounts of the protein substance collagen.Ligaments have two bundles: anteromedial and posterolateral, the precise interaction of which ensures the movement of the joint. When a person bends the leg, the entire load of the ligament falls on the anteromedial bundle, when the leg is straight, the load is transferred to the posterolateral bundle.

The cruciate ligaments perform an important function – they keep the knee joint in a static position, preventing the knee and lower leg from moving under load. The structure of the posterior and anterior ligaments has a number of differences. The posterior cruciate ligament is up to 15 mm thick and 30 mm long.

The ligament passes through the inner condyle from the femur to the back and descends downward. Its fibers are woven into the joint capsule of the knee. What is it for? The posterior ligament restrains the knee, preventing it from overbending. The posterior ligament is formed by the anterolateral and posterior medial bundle.

Another important knee ligament is the medial collateral ligament. It performs a stabilizing function, preventing the joint and bone of the lower leg from displacing from its position through the dislocation of the condyle.The ligament has two parts – deep and superficial. The long fiber surface is the main stabilizer. Its fibers are connected to the femur through the inner condyle and the tibia through the medial metaepiphyseal regions. The deep part of the ligament is made up of short fibers that extend to the meniscus ligaments of the tibia and femur.

Behind the medial collateral ligament is the posterior medial capsule of the joint, which supports the knee in a stable position. The capsule consists of long fibers that are directed towards the postero-caudal side. Therefore, this section of the capsule is called – the oblique ligament, which performs the same functions in the knee joint as the medial ligament.

The fact that the oblique ligament, which is part of the capsule, is separated into a separate element of the knee, is of practical importance in terms of ensuring the stability of the joint. The oblique ligament is one of the most important elements of the ligamentous apparatus of the knee.

The posterolateral and lateral parts of the ligamentous apparatus of the knee are represented by several tendons, which make up a complex ligamentous complex.Their main purpose is to maintain and maintain the stability of all parts of the knee, to prevent the lower leg from bowing when loading the limb.

Muscles are responsible for ensuring that the knee moves in three planes, but at the same time remains stable. Their purpose is especially important in cases where the stabilizing ligaments are injured and cannot perform their function.

One of the largest and most important muscles in terms of anatomical structure is the quadriceps femoral muscle.It is this muscle that is given special attention when the patient is undergoing rehabilitation after injuries of the ligamentous apparatus of the knee. The extent to which its condition and functioning will be restored depends on the further work of the joint.

At the same time, the quadriceps muscle is not only one of the main functioning elements, but also an indicator of pathological processes occurring in the knee. When there are no symptomatic signs of knee disease, the quadriceps muscle begins to atrophy and loses some of its strength.This muscle supports the joint in those moments when, due to injury to the tendons and ligaments, the knee loses its stability.

Biomechanical processes

The knee joint has a very complex biochemical system. When it is necessary to diagnose a knee injury, the nature of the interaction of absolutely all parts of the joint is studied. To make it more clear what the knee joint is, the basics of its anatomical structure can be described quite simply: the knee has anterior, posterior, medial and lateral sections, which are complexes of muscles, ligaments and tendons.Thanks to the well-coordinated work of all parts of the knee, its stability and physical activity are ensured:

1. The quadriceps muscle is a stabilizer that provides knee extensor function and prevents pathological displacement of the lower leg bone.
2. The medial part of the joint protects it from external influence of rotational factors.
3. The posterior part of the knee, which includes the semi-membrane muscle and the semi-tendon, does not allow the knee to move under the influence of external forces.
4. The muscle located under the knee prevents menisci from being pinched.
5. The lateral ligament, which is responsible for strengthening the knee, has a strong connection with the meniscus.
6. The main knee link is the cruciate ligaments. Their presence provides the ability to flex and extend the knee. The anterior cruciate ligament supports the lower leg. If it breaks, the joint loses its stability.

Knee physiology and pathophysiology

Bone, cartilaginous and soft tissues of the knee, providing its motor function, are in close interaction.Bones and cartilage constantly rub against each other. To prevent them from being erased and injured, there is synovial fluid between all the constituent elements, which is a lubricant and a shock absorber.

The surface of all bone elements is covered by hyaline cartilage. Protective cartilage tissue consists of collagen, chondrocytes and other substances. There is also a germ layer in the cartilage. When an excessive load is placed on the knee, the chondrocytes and the growth layer balance the intensity of the load, preventing the destruction of cartilage tissue.Due to the presence of collagen, the covering of the bone tissue can withstand great pressure.

Chondrocytes are the centers in which the process of metabolism of all substances necessary for maintaining the normal condition and functioning of the knee cartilage takes place. They are protected by a network of collagen fibers. Chondrocytes secrete special substances – proteoglycans, the main task of which is to attract water molecules to themselves and create from them the main constituent substance of bone tissue.

Chondrocytes are incapable of regeneration and self-recovery.Gradually, when a person first grows up, then physiological changes associated with aging begin to occur in his body, chondrocytes also wear out. In this regard, the structure of the protective cartilaginous layer of the bone elements of the joint changes, as a result of which the joint cannot withstand the same degree of load.

This process of gradual destruction of the protective layer has physiologically similar features to the mechanical injury of the knee. If a strong blow or a sudden, excessive load is required to rupture a ligament or joint muscle, then in elderly people, when the cartilaginous layer of the bone parts of the knee wears out, injury can happen suddenly, without factors predisposing to it.

There is a concept in traumatology of “indirect injury” – a person suddenly stopped at the moment when the knee performed a rotational movement, while the patella was partially dislocated. This indirect damage is accompanied by a rupture of cartilage tissue, a cut of the edge of the patella.

Damage to cartilage tissue occurs due to the fact that ligaments and tendons (due to age-related changes in the body) lose collagen and become pathologically stretched. When the ligaments lose their stabilizing function, the knee gradually loses its stability.The joint capsule stretches and puts pressure on the walls of the blood vessels. For this reason, the metabolic process is disrupted, the cartilage does not receive the required amount of nutrients.
When the cartilage can no longer withstand the stress placed on it, microscopic cracks appear on its surface. The next stage of this pathological process is the destruction of collagen fibers. Necrotic foci begin to form on the bone tissue.

Dead bone material is peeled off, and its microscopic particles enter the joint cavity.As a result of these changes, chondrocytes can no longer synthesize the substances necessary to maintain the normal state and full functioning of the joint. The gradual process of destruction occurs not only in the cartilage tissue, but also on the bone elements of the knee.

Thus, the anatomical features of the knee and biochemical processes are in close interaction and influence each other. Knowing how each part of the joint functions separately and in conjunction with the rest of the elements, you can choose an effective therapy for the treatment of various knee injuries.The most effective and gentle knee treatment methods will be selected by the experienced specialists of the Center for Sports Traumatology and Rehabilitation Medicine.

90,000 Brief Anatomy of the Knee

The knee is the largest joint in the human body and is a common source of sports injuries. The knee joint is made up of bones, cartilage, ligaments, tendons, bursae, and the meniscus. Trauma to any of these elements can cause knee pain.

Bones of the knee joint

The knee joint consists of three bones:

• Tibia (shin). It is the main bearing bone of the lower leg and connects to the lower femur to form the knee joint.
• Femur (thigh). It is the longest and strongest bone in the human body and connects at the bottom to the tibia and patella (patella).
• Patella. Located on the anterior surface of the lower thigh, forming the patellofemoral joint with the femur.

In a healthy knee joint, the back of the patella and the notch of the femur are covered with cartilage, allowing the two bones to move relative to each other without friction or pain.

Muscles of the knee joint

Mobility of the knee joint is provided by the quadriceps muscle and the muscles of the back of the thigh.

• Quadriceps femoris. Consists of four heads (rectus femoris, vastus lateral, vastus medial, vastus intermediate) located on the front of the thigh. These muscles are attached to the knee joint through a common tendon. Contraction of the quadriceps muscle leads to extension of the lower leg in the knee joint (the leg is straightened).
• Muscles of the back of the thigh. This is a group of three muscles (the biceps (biceps) of the thigh, the semimembranosus, and the semitendinosus) located on the back of the thigh. Contraction of these muscles leads to flexion of the lower leg at the knee joint.

Injuries to these muscles can range from mild sprains and bruises to complete rupture.

Knee cartilage

Slippery and flexible hyaline (articular) cartilage provides less friction within the knee joint than glass friction against glass.There are two main types of cartilage in the knee joint:

• Articular (hyaline) cartilage. While smooth and strong at the same time, it allows bones to move relative to each other with minimal friction.
• Meniscus (fibrous cartilage tissue). Menisci are two C-shaped cartilage structures found in the knee joint. The medial (internal) and lateral (external) menisci act as airbags, providing shock absorption between the touching femur and tibia.

Articular cartilage and menisci are integral to the proper functioning of the knee joint. They can be injured suddenly or gradually as a result of frequent micro-injuries.

Knee ligaments

Ligaments are flexible fibers made of connective tissue that connect one bone to another.

• Anterior cruciate ligament (ACL). ACL connects the tibia to the femur and prevents the tibia from moving forward relative to the femur.ACL is usually injured by sports.
• Posterior cruciate ligament (PCL). It also connects the tibia to the femur and acts to prevent the tibia from moving backward relative to the femur. ZKS together with ACL provide knee joint stability. Less likely to be injured than ACL.
• External collateral ligament (LNL). It is also called the peroneal collateral ligament and is located on the outside (side) of the knee.This ligament connects the outer lower edge of the femur to the outer upper edge of the fibula. The NCC helps stabilize the knee joint by limiting external, inward force.
• Internal collateral ligament (ICL). It is located on the inner (medial) side of the knee joint, connecting the inner lower edge of the femur to the inner upper edge of the tibia. The VKS helps stabilize the knee joint, preventing unwanted side-to-side movements with the NCL.VKS is the most commonly injured ligament of the knee joint.

Tendons of the Knee

Tendons are flexible fibers made of connective tissue that attach muscles to bones.

• Tendons of the muscles of the back of the thigh. Three tendons cross the knee joint posteriorly. Two are on the inside of the knee, attaching to the tibia (semimembranosus and semitendinosus tendons), and one on the outside of the knee, attached to the fibula (biceps femoris).
• Quadriceps tendon. It consists of four tendons of the quadriceps heads (rectus femoris, vastus lateralis, vastus medialis, vastus intermediate) and attaches them to the top of the patella.
• Hamstring. This tendon (also called the patellar propria ligament) attaches the bottom of the patella to the top of the tibia.

In addition, the knee joint is surrounded by a synovial membrane (membrane), which provides lubrication of the articular surfaces and the supply of nutrients.

Popliteal muscle: Anatomy and function

The popliteal muscle is a thin, flat muscle that forms the bottom of the popliteal fossa. This is the deepest muscle of the knee joint, which, unlike other muscles of the lower limb, acts on only one joint.

Anatomy

Start

The muscle starts from the lateral condyle of the femur and the posterior horn of the lateral meniscus, then descends medially and attaches to the tibia.Because the popliteal muscle (PM) runs behind the top of the tibia and joint capsule, it is the deepest muscle in the knee joint.

Georgy Temichev’s seminar “Diagnostics and therapy of lower limb problems. Analysis of walking and running ”. Learn more…

Her tendon pierces the joint capsule (but does not enter its cavity), and intersects with the arcuate ligament, the lateral collateral ligament and the tendon of the biceps femoris.The popliteal bursa, which is usually an extension of the synovial membrane, separates the muscle from the lateral condyle of the femur. An additional PM head can be formed from the lateral head of the gastrocnemius muscle.

Attachment

PM attaches to the tibia, slightly proximal to the line of the combus muscle, but below the tibial condyles.

Innervation

PM is innervated by the fibers of the tibial nerve (L4-S1), starting directly from the section of the nerve that innervates the posterior tibial muscle, and also (in some cases) the nerve that innervates the knee joint.These nerve fibers go to the PM as part of the fourth and fifth lumbar nerves, as well as the first sacral spinal nerve.

Blood supply

The popliteal muscle is supplied by the muscle branches of the popliteal artery.

Popliteal muscle functions

PM assists the flexor muscles of the knee joint.

• When the knee is bent under conditions of an open kinematic chain, the PM rotates the tibia medially.
• Under conditions of a closed kinematic chain, the PM rotates the femur laterally (at the very beginning of knee flexion).
• PM pulls the lateral meniscus back during knee flexion, therefore preventing knee injury.
• PM is often connected to the lateral part of the knee joint capsule. This gives the muscle the ability to stabilize the knee joint in the posterior-lateral region. Krudwig views the PM as an important structure that prevents excessive external rotation of the tibia, even if all posterolateral ligaments are cut.

Clinical significance

Poor posture and irrational movement patterns can lead to excessive stress on the PM, which contributes to its weakness and injury.Any knee injury will affect the PM.

If there is an imbalance in the hamstrings, then the PM will weaken. Excessive pronation and collapse of the inner part of the foot while walking or running will also strain it.

Various EMG studies have shown that popliteal muscle activity increases with knee extension and downhill walking, so it plays an important role in controlling knee hyperextension.

Diagnostics

Because of its deep location, isolated PM injury is rare, but it can occur in association with other knee injuries such as anterior cruciate ligament or meniscus injury.

There are common symptoms of muscle damage such as swelling, soreness, swelling, bleeding. If the PM is damaged, the patient may try to keep the leg (lower leg) in the position of external rotation during knee flexion.

To exclude damage to the PM, check the following:

• Soreness. Since many neurovascular structures lie on top of the muscle, only its terminal sections can be palpated. The proximal part of the PM is palpable in the prone position.Soreness in the posterior-lateral part of the knee joint may indicate damage to the tendon of the biceps femoris or lateral meniscus.
• Garrick’s test. In a sitting position with the knee and hip joints flexed at 90 degrees, the resistance of the lower leg to external rotation should be checked. The test is considered positive when pain occurs.
• Pain when taking off shoes. The patient tries to remove the boot from the healthy leg, resting (medial rotation) against her heel with the toe of the injured leg.The test is considered positive when pain occurs.

As mentioned earlier, isolated damage to the PM is rare, and an isolated rupture of its tendon was found in 2 of 2412 cases (on MRI of the knee joint).

The popliteal muscle, together with the posterior cruciate ligament, stabilizes the femur over the fixed tibia in the stance phase, especially when additional stability is required, such as when running downhill.

Thus, running downhill and overpronation results in PM injuries such as tenosynovitis, tendinopathy, sprain or rupture.

Treatment

Treatment of acute PM injury is the same as for any other soft tissue, muscle or tendon injury. Use the RICE or PRICE protocol (protection, rest, ice, compression, elevation) and NSAIDs.

Physical therapy in this case is of the same importance as in other pathologies associated with damage to soft tissues, muscles or tendons. This includes exercises for mobility, strength (such as an eccentric training protocol), endurance, etc.e. It all depends on the patient’s condition and related problems.

Source: Pysiopedia – Popliteus Muscle.

Surgical anatomy and biomechanics RAKS

Some questions of surgical anatomy and biomechanics of the knee joint extensor apparatus.

The extensor apparatus (RA) of the knee joint (KJ) includes the tendon of the quadriceps femoris muscle (HRM), the patella (N) with its supporting ligaments, and the patellar ligament (CH).The greatest role in the extension of the lower leg is played by the straight head of the HGM. This bicarticular muscle starts from the upper-lower spine of the ilium and the upper edge of the lip of the glenoid cavity; external and internal heads (external and internal broad muscles of the thigh) start from lin. aspera of the thigh, and the intermediate head (broad intermediate muscle) from the intertrochanteric line. All of them, as part of a single and powerful tendon extension, are attached to the upper pole of the patella.

Tendon extension appears to be uniform, but has different attachment points.So, the tendon of the straight head (except for the thin anterior plate that runs anterior to H and forms its own tendon extension) is attached to the anterior edge of the upper pole, and parts of the tendon of the lateral heads are woven into the depression between the anterior and posterior edges of H. The remaining parts of the tendon are external and the inner heads of the HGM pass directly into the ligaments surrounding and supporting the patella. On the anterior surface of the CS from the retinaculum patellae, two patello-tibial ligaments extend at an angle.Fig 1. As well as retinaculum patella, they have no particular effect on the function of extension in the knee joint.

Complete restoration of the extensor function after firm osteosynthesis of the patellar fracture without restoring the torn supporting ligaments can serve as a proof of this fact. The main stabilizer of the patella, which protects it from external displacement, is lig. patello-femoralis medialis, which often ruptures or breaks off when N.

Each muscle, in addition to the general tendon stretch, has its own tendon, the shortest at the inner head and the longest at the intermediate. The length of the tendon is important in determining the degree of extensibility (i.e. elasticity) of the muscles, and the shorter the tendon (and therefore the longer the abdomen of the muscle), the greater the extensibility of the muscle.

Normally, the broad internal and external muscles approach the H at an angle of 55-60 ° and ensure its balance. The inner head consists of two parts: the vastus medialis longus (provides tension on the patella at an angle of about 15 °) and the vastus medialis obliquus (the muscle fibers run more horizontally, on average at an angle of 55 °).The main task of the oblique portion is to resist the contraction of the most powerful outer head. Therefore, the broad internal oblique muscle is the most important dynamic stabilizer of the patella.

According to S. Stanitski [2003], the “work” of the RAKS resembles the work of a gate as a lifting mechanism. Fig 2. Depending on the position of the joint (flexion – extension) due to the change in the lever arm, the contraction force of the HGM and the patellar ligament changes.

All HGM heads are involved in extension to varying degrees.So, one straight head provides extension to an angle of about 160-165 °, and only then both lateral heads are included in the process. The intermediate head, located most deeply posteriorly, participates in the most final phase of extension. By itself, it cannot even shift H upward. Another thin articular muscle of the knee (m. Articularis genus) is located on the bone, consisting of flat longitudinal muscle bundles that stretch the articular capsule, but it does not take part in the extension of the lower leg.

Fig. 1. Topographic relationships of the RAKS. Fig. 2. The principle of operation of the RAKS. When flexing, the load on the HGM tendon and the patellar ligament increases sharply.

Such a three-layer structure of the tendon extension of the HGM explains its high mechanical strength and therefore, even with closed fractures of the distal end of the femur, tendon damage almost never occurs. In addition, such a structure with a separation of attachment sites explains the fact that in practice there are cases of rupture of not all layers of tendon extension, but only a straight head or a straight head and one of the lateral heads.

HGM is relatively well supplied with blood due to the envelope of the deep and external thigh artery; innervated by the branches of the femoral nerve.

When extending in the knee joint, sliding and displacement of all elements of the RARS in relation to each other and the femur occurs, with full extension, the displacement of H upwards reaches an average of 8 cm.Mucous bags and the synovial membrane (especially the upper volvulus). Rice. 3.

In addition to the function of extension, the RAKS plays another important role as an active dynamic synergist of the posterior cruciate ligament, and during flexion of the joint, the HGM prevents the posterior displacement of the lower leg. The role of HGM in active rotation of the lower leg has not been sufficiently studied. Between the central axis of the thigh and the direction of the patellar ligament, there is an angle Q (angle quadriceps), normally 15-20 °. By the value of this angle, the HGM can rotate the lower leg. Rice. 4.

In this case, both broad lateral muscles act as rotator antagonists.For example, the outer head, pulling the patella to the outer condyle of the thigh, counteracts further internal rotation of the lower leg.

According to Cadilchak et al. [1978], a different qualitative representation of muscle fibers was noted in different heads. In the outer, type 1 fibers are better represented, providing endurance in a static position, and in the medial, there are more type 2 fibers for explosive, rapidly changing phase contractions.

The patella is the largest sesamoid bone, has the shape of a triangle, with the apex directed distally.According to Grelsamer et al. [1994], based on a study of 564 patients, the length of the patella ranges from 47 to 58 mm, and the width – from 51 to 57 mm. A special form of the patella was discovered with a very long, not involved in articulation, lower pole, it was named “Cyrano”, in honor of the long nose of the famous literary character.

Rice. 3. “Path” of the patella during flexion – extension of the knee joint. Fig.4. Angle Q is formed by the intersection of the lines connecting the anterior-superior spine with the center of the patella and the line of direction of its ligament.

The articular surface of H has 7 facets, and the longitudinal tubercle divides it into two unequal parts (the lesser medial and the greater lateral), each consisting of 3 facets, the seventh, the median, is a narrow longitudinal facet on the medial side of the bone. The degree of contact of each of the facets depends on the angle of flexion in the joint. Fig 5.

When the joint is extended, only two lower facets are in contact with the thigh, the proximal facets are tightly pressed to the femoral condyles only with full flexion, and the main load falls on the inner facet due to the larger size of the internal condyle.Normally, almost 25% of the patellar length does not participate in articulation (these data will be of particular importance in substantiating the indications for patellar resection in comminuted and multi-comminuted fractures of the lower pole).

Supporting ligaments and tendon extension are essential for patellar stability. The external and internal retinaculum consist of longitudinal fibers of the aponeurosis of the external and internal broad muscles, together with the wide fascia and two patello-tibial ligaments, they are woven into the patella and into the upper border of the tibial plateau, preventing lateral displacements of N.

Internal broad muscle is thinner and weaker. It is not supported by such a powerful mass as the iliotibial tract, which attaches externally to the Gerdy tubercle. In many respects, these anatomical features explain the prevalence of external dislocations of H, although the main cause of the usual dislocation is considered to be dysplasia of the lateral femoral condyle and hallux valgus.

Theut and Fulkerson [2003] showed that an oblique portion of the inner head of the HGM (VMO – vastus medialis obliquus) is able to resist 60% of the forces displacing H outward.Another 22% of protection is provided by the medial retinaculum and the medial menispatellar ligament. Thus, the function of VMO is more to limit lateral displacement of the patella than to extend the lower leg.

The blood supply of H is uneven and is carried out mainly through the branches of a. genucularis and a. genus. According to Scapinelli [1967], the lower pole and the middle part of the bone are better supplied with blood, which probably explains the cases of aseptic necrosis of the upper H pole and the more frequent development of arthritic changes in the upper part of the patellofemoral joint (PFC).

In the literature, we found a description of 41 cases of aseptic necrosis of the proximal fragment after fracture H [Scapinelli R., 1967]. Circulatory disorders in it were radiologically detected as early as 1-2 months after the injury, in most cases they were asymptomatic and ended in spontaneous revascularization. In our practice, we also encountered similar complications, but it can be assumed that in most cases they are visible.

The patellar ligament (CH) is strong and strong.Its length, on average, is 4.5 cm, width is up to 3–3.2 cm, and thickness is up to 1 cm. Normally, the ratio of the length of the ligament (the distance from the lower pole of H to the apex of the tibial tuberosity) to the length of the patella, measured by lateral radiograph, does not exceed 1.2. Rice. 6.

The exact ratio of these dimensions must be observed, for example, for resections of the distal part of the patella; in addition, the low position of H (patella baja) with a short, wide ligament makes it impossible to use it as a plastic material for reconstruction of the anterior cruciate ligament.

The ligament starts from the lower pole of the H and is attached to the tuberosity of the tibia, along the posterior surface it is intimately connected with the joint capsule, and therefore, when it is ruptured or torn off, there is always a concomitant rupture of the joint capsule. In the upper part (at the lowest pole), under the ligament, there is a fat pad, which largely provides blood supply to the entire heart failure. This must be borne in mind, for example, in the case of transligamentous access to the joint according to Daniel et al. [1990], so as not to disturb the nutrition of the ligament already weakened by excision of the graft.

The fatty body consists of many fatty lobules, each of which is covered with synovium. It not only participates in the blood supply to the ligament, but also provides shock absorption and regulates the movement of the joint fluid.

Fig. 5. The position of the patella depending on the angle of flexion in the joint Fig. 6. Insall-Salvati Index. Normal ratios of the length of the patella and its ligament. If LT exceeds LP by more than 1 cm, then this leads to a high position of the H – patella alta.

In the distal part of the ligament posteriorly, almost at the site of attachment to the bone, there is a large mucous bag – b.infrapatellaris prof., from the front, the ligament is covered with a strong fascia, which can be used to close the defect after taking the graft. Between the ligament and the iliotibial tract (ITT), there is a space that can be easily penetrated with an antero-external approach using the Kentch-Muller approach.

Internally, to the distal third of the CH, there is a tendon extension – “crow’s feet”, including the tendons of the sartorian, tender and semitendinosus muscles. This tendon formation can be used during the Slocum-Larsen operation to correct the rotational instability of the joint, and its individual elements can be used to replace the cruciate and tibial collateral ligaments (Lindemann, Ellison, Cho, etc.), with the usual dislocation of the patella (Galeazzi operation).

The site of the distal attachment to the tuberosity is wide and strong, which explains the predominance of avulsion fractures, rather than detachments of the ligament itself, in adolescents with an unclosed growth zone. In the future, due to such a fracture, the premature closure of the secondary center of ossification can lead to deformation – genu recurvatum.

The role of the patella in the extension function is controversial. The most common point of view is that it protects the articular cartilage of the femoral condyles from damage, transfers the efforts of the HGM and, due to changes in intra-articular pressure during movement, improves diffusion processes, thus participating in the nutrition of the articular cartilage.

It is well known that cartilage H is nourished both by subchondral vessels (Fig. 8) and by diffusion of synovial fluid, which depends on variable pressure during flexion / extension in the joint. These two components ensure the exchange of cartilage cells to a depth of 3 mm, i.e. depth exceeding the thickness of the hyaline cartilage H. Without a change in pressure, exchange is possible only to a depth of 1.7 mm [154].

There is another point of view about the functional significance of N.Back in 1937, Brooke, (he was the first to call H the sesamoid bone), denied its importance in transmitting the extensor forces of the HCM and even insisted that the extensor mechanism was more effective without the patella. We meet similar assumptions in a number of other, later works [Watson-Jones R., 1972].

However, most podiatrists believe that H plays an important role in extension because without it, the lever arm is sharply shortened, which leads to a decrease in the extension force. Rice. 7.

Fig. 7. The mechanical role of the patella. a – the patella increases the moment of the PAKS shoulder (i.e., the length of the vector of the direction of the force to the center of rotation), c – after the patella is removed, the shoulder is shortened, and the extension force is significantly reduced.

Tendinopathy of the own patellar ligament | Inflammation of the tendon of the quadriceps femoris

What is patellar tendinopathy and why does it occur

Tendinopathy of the patellar tendinopathy (apex syndrome, jumper’s knee, inflammation of the patella’s own ligament) is characterized by pain around the patella.The condition occurs after an unusual or excessive load on the patella’s own ligament. Examples of such loads are intense jumping (basketball, volleyball), and activity accompanied by a large number of sudden movements and stops (tennis, badminton) or rapid changes in direction of movement (football).

The disease is also common among runners. Hence another name – runner’s knee ¹ .

Synonyms

The following synonyms are used to denote tendinopathy of the intrinsic patellar ligament:

• Apex of the patella syndrome
• Runner’s knee
• Jumper’s knee

Anatomy of the knee joint

The knee joint is a movable joint of three bones: the thigh (lat.femur), tibia (Latin tibia) and patella (Latin patella).

A powerful tendon of the quadriceps femoris is attached to the patella from above, and from below it continues in the form of the patella’s own ligament, which attaches to the tibia. The main function of the tendon is to transfer force from the extensor muscles to the lower leg, so it is subjected to constant stress during sports.

Risk factors and causes

Anatomical factors

• The quality of the tendon connective tissue gradually deteriorates with age
• Violation of the knee joint axis
• Foot deformities
• Shortening of tendons and muscles
• Structural abnormalities, for example, varus / valgus of the knee joints
• Congenital weakness of the ligamentous apparatus
• Osgthera disease

External factors

• Unsuitable footwear
• Violation of exercise technique during sports
• Walking on a hard surface, for example, asphalt
• Excessive training
• Unusual stress, for example, starting sports too intensively

Sports

• Frequent jumping sports – volleyball, basketball, some athletics such as long jump and high jump; hence the name “jumper’s knee”
• Running – hence the name “runner’s knee” 1
• Sports associated with frequent changes of direction of movement – football, handball
• Sports associated with abrupt stops and starts – tennis, squash, badminton

Stages of the syndrome of the apex of the patella

In the medical diagnosis, the stages of the disease are usually not indicated, but they help to better understand the clinical picture. ²

At first, the pain is felt only after playing sports.In the future, “starting” pain appears during sports or when performing normal movements, for example, climbing stairs or climbing after a long sitting position. Symptoms typically persist in undulating patterns over many months or even years. Periods of mild pain are followed by intense pain after exertion. Two knee joints are affected at once in 20-30% of patients. Ultrasound examinations of blood vessels, magnetic resonance imaging (MRI), and x-rays of the knee are used for examination.

Treatment

Inflammation is usually treated conservatively, without resorting to surgery. The operation is only necessary if the ligament is torn.

Physiotherapy exercises

Exercise can train muscles and increase joint mobility.Exercise can speed up the healing process if done regularly. Usually a set of exercises is recommended by the attending physician. Depending on the diagnostic findings, ultrasound therapy, electrotherapy, transverse massage, manual therapy, etc. can be prescribed.

Tensile

Regular muscle stretching reduces tension in the tendon.

Bandages

Specially developed braces stabilize the knee joint.Belted braces, such as Genumedi PSS, are especially effective because the straps anchor the tendon and thereby reduce tension on the tendon fibers.

Cooling

Cold compresses and packs of cooling liquid relieve pain (temperature should be about 7 °).

Heat

Warming up and massaging with a warm towel improves blood circulation in the tendon attachment area.

Drug therapy

If necessary, your doctor will prescribe anti-inflammatory drugs, such as ibuprofen or diclofenac, for 1 to 2 weeks.

Local treatment

Anti-inflammatory ointments and gels can be used topically several times a day.This speeds up recovery.

Insoles

Orthopedic insoles such as the igli Allround optimize the biomechanics of the knee joint.

Massage

Massage reduces pain. An experienced massage therapist can relax muscles and improve blood circulation in the area of ​​inflammation in a few sessions.

Treatment is selected individually in accordance with the characteristics of the clinical picture and the individual needs of the patient.

A set of exercises for tendinopathy of the own patellar ligament

It is recommended to do exercises to stabilize the knee joint and strengthen the patella’s own ligament.Medi has partnered with Dr. Matthias Marquardt, a sports physician and active athlete, to create a training program. The program contains eleven exercises that you can do at home. In the videos, Dr. Mathias Marquardt teaches professional triathlete and physical therapist Laura Philippe how to do the exercises correctly. Ideally, exercise should be done three times a week.

Before exercising, you should consult with your doctor and find out if they are suitable for you.

Strength training

Coordination

Exercises on a stabilizing platform are ideal for developing balance and coordination skills.Exercise barefoot. Thanks to the soft foam, you sink a little into the mat and must compensate for the artificial instability . It improves proprioceptive skills (proprioception – the sense of the body in space) and increases muscle strength.

Stand on one leg

Training of the muscles of the foot and thigh

Equipment:

Thick rug (alternative: folded towel or folded mat)

Starting position:

• Place your bare foot on the mat
• Knee should be slightly bent
• Raise the other leg (fig.1)

Exercise:

• It is necessary to constantly compensate for instability resulting from being on a soft surface

• Make sure that the muscles of the trunk are tense and keep the body in an upright position
• Keep your back straight to make your maximum growth

Options:

• You can make the exercise easier by standing on a hard surface
• You can complicate the exercise by drawing eights with a raised leg (Fig.2)
• You can complicate the exercise by bending your leg at the hip joint (Fig. 3)
• You can complicate the exercise by closing your eyes

Execution mode:

• Hold the position for 30 seconds
• Repeat the exercise on the other leg
• Take a 15 second break between exercises

Puppet

Training of the muscles of the foot and trunk

Equipment:

Thick rug (alternative: folded towel or folded mat)

Starting position:

• Place your bare foot on the mat
• Knee should be slightly bent
• Raise the other leg (fig.1)

Exercise:

• Raise the other leg and both arms (fig. 2)
• Slowly spread the limbs to the sides
• It is necessary to constantly compensate for the instability resulting from being on the soft surface

• Watch, so that the muscles of the trunk are tense and keep the body in an upright position
• Keep your back straight to maximize your height

Options:

• You can ease the exercise by standing on a hard surface

Mode of execution:

• Do 3 sets of 10 reps with each leg
• Take 15 second breaks between sets

Partial knee flexion

Training of the muscles of the foot and thigh

Equipment:

Thick rug (alternative: folded towel or folded mat)

Starting position:

• Place your bare foot on the mat
• Knee should be slightly bent
• Raise the other leg
• Extend your arms up and the other leg back, tilting your torso forward approximately 20 ° (fig.1).

Exercise:

• Perform mini squats by flexing the knee joint to approximately 30 ° (fig. 2)
• It is necessary to constantly compensate for the instability resulting from being on the soft surface

• Arms, trunk and the raised leg should be in one line
• Make sure that the muscles of the trunk are tense
• Keep the raised leg straight
• Do not roll the knee inward

Options:

• You can make the exercise easier by standing on a firm Surfaces

Execution Mode:

• Do 3 sets of 10 reps with each leg
• Take 15 second breaks between sets

Strength training

When performing dynamic exercises, there is an alternation of two types of muscle fiber contraction: eccentric and concentric.

During concentric phase (lift-off phase, positive phase), resistance is overcome. In the case of one-legged squats, this is a straightening of the leg when the muscle contraction overcomes the body weight. In the concentric phase, the muscle is shortened. The resulting movement is often called positive.

During the eccentric phase (negative phase), the muscle counteracts inertia or gravity. In the case of squatting, knee flexion occurs in an eccentric phase.In this case, the muscle controls the movement of the body under the influence of an external force. The length of the muscle is stretched during the eccentric phase.

Performing eccentric exercises is especially effective in treating apex of the patella syndrome.

Squats on one leg

Hip extensor training

Starting position:

• Stand on one foot on a flat, firm surface (Fig.1)
• Slightly bend the supporting leg at the knee

Exercise:

• Perform squats on one leg, bending the knee to approximately 60 °
• Make sure that the muscles of the trunk are tense
• Make sure that the knee is not in front toes
• Make sure that the knee does not tilt outward or inward
• Exercise slowly

Options:

• You can make the exercise easier by holding on to a handrail or other support
• You can complicate the exercise by standing on an incline (25 °)

Execution mode:

• 3 sets of 15 repetitions with each leg
• Take 30-second breaks between sets

inclined plane (25 °).

Squats on one leg on an incline

Training of the hip extensors and mobilization of the own patellar ligament

Equipment:

25 ° inclined surface

Starting position:

• Standing exactly on one leg on an inclined surface
• Bend the supporting leg a little at the knee
• Bend the non-supporting leg (Fig.1)

Exercise:

• Bend the supporting leg to approximately 60 ° (fig. 2)
• Make sure that the muscles of the trunk are tense
• Make sure that the knee is not in front of the toes
• Make sure that the knee did not lean outward or inward
• Exercise slowly

Options:

• You can make the exercise easier by doing it on a firm, level surface
• You can make the exercise easier by holding on to a handrail or other support
• it with weights (for example, with a backpack)

Execution mode:

• 3 sets of 15 repetitions each leg
• Take 30-second breaks between sets

Lunge

Training of the posterior thigh muscle group

Starting position:

• Standing, feet shoulder width apart
• Make a wide lunge forward so that the heel behind the standing leg comes off the floor
• Keep your back straight (Fig.1)

Exercise:

• Lower the knee on the back of the leg to the floor and shift the weight to the leg in front, while bending it at the knee (fig. 2)
• Keep your back straight
• Raise a little
• Then again lower the knee on the back of the leg to the floor and load the leg in front
• To intensify the workout, move the knee so that it is in front of the toes
• All movements must be performed slowly and in a controlled manner

Option:

• You can complicate the exercise by standing on an incline (25 °)

Execution mode:

• 3 sets of 15 repetitions each leg
• Take 30-second breaks between sets

When you learn how to do the exercise correctly and safely on the horizontal plane, e It can be complicated by performing on an inclined plane (25 °).

Lunge on an incline

Training of the posterior thigh muscle group

Equipment:

Inclined surface (at an angle of 25 °)

Starting position:

• Standing, feet shoulder-width apart, one leg on an incline
• Take a wide step back so that the heel behind the standing leg does not touch the floor
• Keep your back straight (Fig.1)

Exercise:

• Lower the knee on the back of the leg to the floor and shift the weight to the leg in front, while bending it at the knee (fig. 2)
• Keep your back straight
• Raise a little
• Then again lower the knee on the back of the leg to the floor and load the leg in front
• To intensify the workout, move the knee so that it is in front of the toes
• All movements must be performed slowly and in a controlled manner

Option:

• You can make the exercise easier by doing it on a flat firm surface

Execution mode:

• 3 sets of 15 repetitions each leg
• Take 30 second breaks between sets

Bridge

Training of the posterior thigh muscle group

Equipment:

Gymnastics mat (alternative: towel)

Initial position:

• Lying on your back
• Heels rest on the floor (Fig.1)

Exercise:

• Raise your pelvis
• Tighten your glutes and draw in your abdomen (fig. 2)
• Slowly lower your pelvis
• Then slowly raise your pelvis
• With your pelvis raised, your knees should be bent at right angles

Execution option:

• You can complicate the exercise by performing it with support only on one leg (bend the other at the hip and knee)

Execution mode:

• 3 sets of 10 repetitions (on each leg when doing the harder option)
• take 30-second breaks between sets

Rise on toes

Calf muscle training

Equipment:

Gymnastic step (optional: handrail for support)

Starting position:

• Stand on the edge of the step with the front of the foot
• Bend your knees slightly

Exercise:

• Stand on tiptoe (fig.1)
• Then lower your heels to create a feeling of tension in your shins (fig. 2)
• Stand on tiptoes again
• The surface of the support must not be slippery
• To avoid falling, hold on to the fixed support with your hands

Execution mode :

• 3 sets of 10 reps
• Take 30 second breaks between sets

Stretching of muscles and fascia

Stretching the fascia helps relieve tension.Fasciae are connective tissue sheaths for muscles that surround and stabilize muscles. Roller exercises stimulate blood circulation and have a positive effect on the condition of the fascia.

Iliopsoas muscle

Stretching of the iliopsoas muscle

Equipment:

Gymnastics mat (alternative: towel)

Initial position:

• Lunge position forward
• Lower the knee behind the leg to the floor
• Keep your back straight (fig.1)
• Place your hands on your buttocks

Exercise:

• Push your thighs forward until you feel a stretch in your groin (fig. 2)
• Do not bend your knee so that it is in front of the toes
• If you feel discomfort in the knee behind your leg, do the exercise on a softer surface

Execution mode:

• Hold for 20 seconds
• Repeat three times on each side
• Take 30 second breaks between repetitions

Anterior thigh muscle group

Stretching of the anterior thigh muscle group

Equipment:

Gymnastics mat (alternative: towel)

Starting position:

• Lying on your side
• Bend your lower leg at the knee and hip joint at a right angle (Fig.1)

Exercise :

• Bend the above leg, grab it by the ankle and pull until you feel a tension in front of the thigh
• Keep the thigh parallel to the floor
• The muscles of the abdominal wall must be constantly tense
• Do not bend forward

Run Mode :

• Hold for 20 seconds
• Repeat three times for each side
• Take 30 second breaks between repetitions

Anterior thigh muscle group (on the roller)

Stretching of the anterior thigh muscle group

Equipment:

Gymnastics roller (optional: gymnastics mat)

Starting position:

• Lying on your stomach
• Place the roller under the muscles of the thigh
• Raise your torso and hold it, resting on the floor with the forearms of both hands (Fig.1)

Exercise:

• Slowly roll back and forth on a roller (from hip to knee and back; fig. 2)
• Keep your back straight and your thigh muscles as relaxed as possible
• Start the exercise can be painful, but the pain should not be unbearable

Execution mode:

• 3 sets of 10 rolls forward and backward
• Take 30-second breaks between sets

Posterior leg muscle group (on the roller)

Stretching of the posterior muscle group of the lower leg

Equipment:

• Gym roller
• Optional: gym mat

Starting position:

• Sitting on the floor
• Place one foot on the floor and put the other leg on the roller
• Hands rest on the floor behind the body (Fig.1)

Exercise:

• Lift your glutes off the floor
• Slowly roll back and forth (from Achilles tendon to hamstring and back)
• Help yourself by contracting your trunk muscles (fig. 2)
• Pull the toes away from you – this will relax the back muscle group of the lower leg
• At the beginning, the exercise may be painful, but the pain should not be unbearable

Execution options:

• You can complicate the exercise by putting both legs on the roller at once
• Complicate exercise can be done cross-legged

Mode of execution :

• 3 sets of 10 rolls forward and backward with each leg
• Take 30-second breaks between sets

Bandages medi

Genumedi PSS

medi has developed the Genumedi PSS knee brace for the conservative treatment of tendinopathy of the own patellar ligament.The brace combines the proven properties of a compression cuff with an additional strap to stabilize the patella’s own ligament.

Learn more about Genumedi PSS Brace.

Learn more about diagnosis and treatment

Sources

¹ The term runner’s knee is often used to refer to iliotibial (iliotibial) tract syndrome (TTI).SPBT is the most common cause of pain along the outer edge of the thigh and knee. The syndrome often develops in distance runners. The iliotibial tract is a strip of connective tissue that runs from the anterior superior iliac spine through the outside of the knee joint to the outer edge of the tibia. Due to repeated flexion and extension of the knee joint, the tract rubs against the condyle of the thigh – like a rope rubs against a stone. As a result, inflammation develops.

² Roels et al., 1978

³ Eccentric training means loading a muscle or a tendon by slowing down a weight or a resistance.

90,000 ANATOMY OF THE KNEE JOINT. Department of Faculty Therapy named after Nesterova Intern Normedova I.A.

Knee joint GENERAL ANATOMY

: overview GENERAL ANATOMY General z Largest and most complex joint Joint with greatest range of motion. The femur and tibia meet in all positions; in contact

More details

The role of joints in the body

The role of joints in the body Nature has made man not only an intelligent creature, but also an active one.Work, home, favorite hobby, meeting friends, traveling without all this is simply impossible to imagine

More details

Fascia and Topography. Associate Professor P.N. Rezvyakov

Fascia and Topography Associate Professor Rezvyakov P.N. NECK FASCIA Superficial Own – superficial plate – deep plate Intracaval Prevertebral Superficial fascia Part of the total superficial

More details

BBK UDC K95

BBK 53.54 UDC 611.7 + 615.828 K95 Jean-Pierre Barral Osteopath (D.O.), United Kingdom Member of the Register of Osteopaths of France Diploma of the European School of Osteopathy at Maidstone (United Kingdom) Faculty of Medicine at Paris

More details

Lesson 5. BONES OF THE LOWER LIMB

Lesson 5. BONES OF THE LOWER LIMB The bones of the lower limb form the belt and the free part of the limb. The belt is represented by the pelvic bone (os coxae) and the sacrum (os sacrum).The free part consists of the femoral

More details

Course work. on human anatomy

FSBEI HE “Penza State University” Medical Institute Department of Human Anatomy Course work on human anatomy “X-ray anatomy of the knee joint” Completed by: student of group 17LS5

More details

Anatomy and physiology of the muscular system

Topic: “Anatomy and physiology of the muscular system” (questions for self-control and tests) QUESTIONS for self-control in the discipline “Anatomy and physiology of man” Topic: “Anatomy and physiology of the muscular system”

More details

BASIC HUMAN ANATOMY

BASIC HUMAN ANATOMY Musculoskeletal system Skeleton structure ODS ODS structure Skeleton Muscles ??? What departments does the skeleton consist of? Skeleton sections Brain section Facial section Head skeleton (skull)

More details

SKELETAL-MUSCULAR ULTRASOUND

December 5-9 EXIT CYCLE OF TRAINING IN THE REPUBLIC OF KAZAKHSTAN SKELETAL-MUSCLE ULTRASOUND DEAR COLLEAGUES! WE INVITE YOU TO GO TO TRAINING ON THE OUTBOARD CYCLE OF PROFESSIONAL TRAINING “SKELETAL-MUSCLE

More details

TOPIC “Musculoskeletal system”

1.Bone growth in thickness occurs due to 1) articular cartilage 2) red bone marrow 3) yellow bone marrow 4) periosteum TOPIC “Musculoskeletal system” 2. Lack of calcium and phosphorus observed

More details

Zayats V.V., Dulaev A.K., Dydykin A.V., Prut A.N., Ulyanchenko I.N. Saint Petersburg, 2018

Zayats V.V., Dulaev A.K., Dydykin A.V., Prut A.N., Ulyanchenko I.N. St. Petersburg, 2018 THE RELEVANCE OF IMPROVEMENT OF SURGICAL TREATMENT TECHNOLOGIES IS DETERMINED: -High recurrence rate with conservative

More details

HIP JOINT IN ADULTS

Eugene G McNally HIP JOINT IN ADULTS Anterior hip region The transducer is initially placed in an axial position.Femoral vessels are a great reference point to start

More details

FINAL MYOLOGY LESSON

Questions of the theoretical part FINAL LESSON ON MYOLOGY General myology 1. Types of muscle tissues and features of their structural organization. 2. Skeletal muscle as an organ: development, components, structure.

More details

ARTHROLOGY. The doctrine of the connection of bones

ARTHROLOGY The doctrine of the connection of bones Connections of bones 1) – unite the bones of the skeleton into a single whole, 2) – keep them close to each other and 3) – provide them with greater (less) mobility continuous:

More details

Massage of individual parts of the body: 29 –

individual parts of the body of the head The skin of the scalp has a significant thickness, easily displaced.It contains many sebaceous and sweat glands, and the subcutaneous tissue contains an abundance of blood vessels and nerves. Lymphatic

More details

Written by Administrator: 13 –

Osteology. General patterns of occurrence, development, growth, and structure of bone tissue Topic: Osteology. General patterns of occurrence, development, growth, as well as the structure of bone tissue, types

More details

* Bone joints II

Bone joints II Classification of bone joints 1.Synarthroses (continuous): 1) Syndesmosis 2) Synchondrosis 3) Synostosis 2. Diarthroses (discontinuous) Number of articular surfaces Simple joint

More details

Diseases of the spine and joints

Diseases of the spine and joints Moscow Publishing house AST UDC 66.7 BBK 4.8 C2 All rights reserved. No part of this publication may be reproduced or used in any form, including

More details

ISHEMIC HEART DISEASE

CORONARY HEART DISEASE The program is used to treat and prevent the development of coronary heart disease.1st day: – impact on the area of ​​the right shoulder joint (back and top) – impact

More details

MUSCLES AND FASCES OF THE ABDOMINAL

LESSON 11 MUSCLES AND FASTIONS OF THE ABDOMINAL The muscles of the abdomen (mm. Abdominis) form the anterior, lateral and posterior walls of the abdominal cavity and are divided into three groups: 1 muscles of the anterior abdominal wall; 2 lateral wall muscles

More details

372 LOWER LIMBS.Drawing drawing

372 LOWER LIMBS Figure 14.4.1 of the C. anterior extensor Cc. extensor longus flexor Cuboid flexor of the big toe Calcaneal cuboid head Talonavicular Scaphoid flexor

More details

Animal Anatomy OGAU – Page 26

fossa of the lateral condyle of the femur, the proximal muscle tendon passes under the lateral ligament of the knee joint and, expanding, turns into a triangular muscular abdomen, which ends at the caudal edge of the proximal end of the tibia (Fig.116). The dog often has a sesamoid bone in the proximal tendon.

Function – flexes and penetrates the knee joint.

Innervation: N. femoralis.

Biceps femoris – m. biceps femoris is the most powerful of all the muscles of the pelvic limb. It is located caudal to the hip joint just below the skin. With one head, it starts from the sacrum (very poorly developed in the dog), and the other from the ischial tuberosity. In pigs and ruminants, it closely fuses with the superficial gluteus muscle, forming the gluteus-head muscle (m.gluteobiceps). The muscular abdomen, expanding distally, ends at the lateral edge of the patella, its lateral ligaments and the roughness of the tibia, and then, passing to the fascia of the leg, its caudal part is woven into the common calcaneal (Achilles) tendon (Fig. 108 – 111).

There are two bursae under the biceps femoris muscle, one of which is located in the area of ​​the sciatic tubercle (b. Trochlearis), and the second in the area of ​​the knee joint under its distal tendon (b. Subtendinea m.bicipitis femoris distalis).

Function – powerful extensor of the hip, knee and tarsal joints. With a suspended limb, bends the knee and unbends the hip and tarsal joints.

Innervation: N. tibialis; in pigs and ruminants, in addition, it receives innervation from N. gluteus caudalis.

Caudal abductor of the lower leg – m. abductor cruris caudalis – typical only for carnivores. It has a ribbon-like shape. Starting from the sacro-sciatic ligament, it runs along the mediocaudal edge of the biceps femoris and, reaching the distal third of its muscular abdomen, becomes thinner and merges with its perimisium.

Function – helps the biceps muscle.

Innervation: N. peroneus.

Semitendinosus muscle – m. semitendinosus – located under the skin behind the biceps femoris and forms the posterior contour of the thigh area (Fig. 108 – 111). It originates from the ischial tuberosity, the sacro-sciatic ligament, the sacrum (in the dog and from the first caudal vertebrae), passes into the elongated muscular abdomen and ends on the medial surface of the tibial roughness, as well as on the fascia of the lower leg, where it merges with the distal tendons of the slender and tailor muscles.

In the area of ​​the sciatic tubercle there is a sciatic axillary bursa (b. Ischiadicus m. Semitendinosi), and under the distal tendon there is a tendon bursa (b. Subtendinea m. Semitendinosi).

Function – unbends the hip, knee and tarsal joints. With a suspended limb, it bends and penetrates the knee joint.

Innervation: N. tibialis, N. gluteus caudalis et rr. cutanei femoris.

Semi-membranous muscle – m. semimembranosus – located under the skin medial to the semitendinosus muscle.With a short proximal tendon, it is attached to the caudal edge of the ischial tuberosity, and the distal one ends on the medial condyle of the femur and the medial ligament of the patella. In a horse, it has an additional attachment on the first three caudal vertebrae (Fig. 108 – 111). In a dog, this muscle has two muscular abdomens.

Function – unbends the hip and knee joints. With a suspended limb, it bends and penetrates the knee joint.

Innervation: N.