What are dermatomes? How many are there? Where can they be found? Discover the answers to these questions and more about the spinal nerve distribution and dermatome patterns in this comprehensive guide.

Understanding Dermatomes: What They Are and Why They Matter

A dermatome is an area of skin supplied by a single spinal nerve. There are 31 pairs of spinal nerves in the human body, forming nerve roots that branch out from the spinal cord. These spinal nerves play a crucial role in relaying sensory, motor, and autonomic information between the central nervous system (CNS) and the rest of the body.

Dermatomes are important because they can help healthcare professionals assess and diagnose a variety of conditions, such as radiculopathies (nerve root compression or pinching). Symptoms that occur along a specific dermatome may indicate an issue with a particular nerve root in the spine.

Spinal Nerves: The Key to Understanding Dermatomes

Your spinal nerves are part of the peripheral nervous system (PNS), which connects the rest of your body to the CNS (brain and spinal cord). There are 31 pairs of spinal nerves, grouped and named based on the region of the spine they are associated with:

• Cervical nerves (C1-C8)
• Thoracic nerves (T1-T12)
• Lumbar nerves (L1-L5)
• Sacral nerves (S1-S5)
• Coccygeal nerve (Co1)

Dermatomes: Mapping the Body’s Sensory Areas

Each dermatome corresponds to a single spinal nerve, with the exception of the C1 nerve, which typically does not have a sensory root. As a result, dermatomes are numbered from C2 to S5, with a total of 30 dermatomes in the human body.

Dermatomes have a segmented distribution throughout the body. The exact pattern can vary from person to person, and some overlap between neighboring dermatomes may occur. Dermatomes associated with the torso and core are distributed horizontally, while those in the limbs run vertically along the long axis of the limb.

Exploring the Dermatome Map: From Head to Toe

Let’s take a closer look at the specific areas of the body associated with each dermatome:

Cervical Dermatomes (C2-C8)

• C2: Lower jaw, back of the head
• C3: Upper neck, back of the head
• C4: Lower neck, upper shoulders
• C5: Area of the collarbones, upper shoulders
• C6: Shoulders, outside of arm, thumb
• C7: Upper back, back of arm, pointer and middle finger
• C8: Upper back, inside of arm, ring and little finger

Thoracic Dermatomes (T1-T12)

• T1: Upper chest and back, armpit, front of arm
• T2-T6: Upper and mid-chest and back
• T7-T9: Upper abdomen and mid-back
• T10-T12: Abdomen and mid-back

Lumbar Dermatomes (L1-L5)

• L1: Lower back, hips, groin
• L2-L3: Lower back, front and inside of thigh
• L4: Lower back, front of thigh and calf, area of knee, inside of ankle
• L5: Lower back, front and outside of calf, top and bottom of foot, first four toes

Sacral Dermatomes (S1-S5)

• S1: Lower back, back of thigh, back and inside of calf, last toe
• S2-S3: Buttocks, genitals, back of thigh and calf
• S4-S5: Buttocks

Coccygeal Dermatome (Co1)

• Buttocks, area of tailbone

Dermatomes and Diagnostic Significance

Dermatomes are not only fascinating from an anatomical perspective but also hold significant diagnostic value. By understanding the specific areas of the body associated with each dermatome, healthcare professionals can better assess and diagnose various conditions, such as radiculopathies (nerve root compression or pinching).

For example, if a patient is experiencing pain, weakness, or tingling sensations that follow a specific dermatome, it may indicate an issue with the corresponding nerve root in the spine. This information can be crucial in guiding diagnostic tests and developing appropriate treatment plans.

Exploring the Complexity of Dermatome Patterns

It’s important to note that the exact dermatome pattern can vary from person to person, and some overlap between neighboring dermatomes may occur. This is due to the complex nature of the nervous system and the individual variations in nerve root distribution and sensory innervation.

Healthcare professionals often use dermatome maps and diagrams as a general guide, but they must also take into account the unique characteristics of each patient’s anatomy and symptoms when making clinical assessments and diagnoses.

Conclusion: Unlocking the Secrets of Spinal Nerve Distribution

By understanding the concept of dermatomes and the distribution of spinal nerves, we gain valuable insights into the intricate workings of the human body. This knowledge not only satisfies our curiosity about our own anatomy but also empowers healthcare professionals to better identify and address a wide range of neurological and musculoskeletal conditions.

As we continue to explore the ever-evolving field of human anatomy and physiology, the study of dermatomes and spinal nerve distribution remains a crucial cornerstone in our understanding of the body’s complex and interconnected systems.

Dermatomes Diagram: Spinal Nerves and Locations

A dermatome is an area of skin supplied by a single spinal nerve. There are 31 pairs of spinal nerves, forming nerve roots that branch from your spinal cord.

Your spinal nerves help to relay sensory, motor, and autonomic information between the rest of your body and your central nervous system (CNS).

So why are dermatomes important? How many are there? And where can they be found? Continue reading as we answer these questions and more.

Each of your dermatomes is supplied by a single spinal nerve. Let’s take a closer look at both of these components of the body.

Your spinal nerves

Spinal nerves are part of your peripheral nervous system (PNS). Your PNS works to connect the rest of your body with your CNS, which is made up of your brain and spinal cord.

You have 31 pairs of spinal nerves. They form nerve roots that branch from your spinal cord. Spinal nerves are named and grouped by the region of the spine that they’re associated with.

The five groups of spinal nerves are:

• Cervical nerves. There are eight pairs of these cervical nerves, numbered C1 through C8. They originate from your neck.
• Thoracic nerves. You have 12 pairs of thoracic nerves that are numbered T1 through T12. They originate in the part of your spine that makes up your torso.
• Lumbar nerves. There are five pairs of lumbar spinal nerves, designated L1 through L5. They come from the part of your spine that makes up your lower back.
• Sacral nerves. Like the lumbar spinal nerves, you also have five pairs of sacral spinal nerves. They’re associated with your sacrum, which is one of the bones found in your pelvis.
• Coccygeal nerves. You only have a single pair of coccygeal spinal nerves. This pair of nerves originates from the area of your coccyx, or tailbone.

Your dermatomes

Each of your dermatomes is associated with a single spinal nerve. These nerves transmit sensations, such as pain, from a specific area of your skin to your CNS.

Your body has 30 dermatomes. You may have noticed that this is one less than the number of spinal nerves. This is because the C1 spinal nerve typically doesn’t have a sensory root. As a result, dermatomes begin with spinal nerve C2.

Dermatomes have a segmented distribution throughout your body. The exact dermatome pattern can actually vary from person to person. Some overlap between neighboring dermatomes may also occur.

Because your spinal nerves exit your spine laterally, dermatomes associated with your torso and core are distributed horizontally. When viewed on a body map, they appear very much like stacked discs.

The dermatome pattern in the limbs is slightly different. This is due to the shape of the limbs as compared with the rest of the body. In general, dermatomes associated with your limbs run vertically along the long axis of the limbs, such as down your leg.

Your dermatomes are numbered based on which spinal nerve they correspond to. Below, we’ll outline each dermatome and the area of the body that it’s associated with.

Remember that the exact area that a dermatome may cover can vary by individual. Some overlap is also possible. As such, consider the outline below to be a general guide.

Cervical spinal nerves

• C2: lower jaw, back of the head
• C3: upper neck, back of the head
• C4: lower neck, upper shoulders
• C5: area of the collarbones, upper shoulders
• C6: shoulders, outside of arm, thumb
• C7: upper back, back of arm, pointer and middle finger
• C8: upper back, inside of arm, ring and little finger

Thoracic spinal nerves

• T1: upper chest and back, armpit, front of arm
• T2: upper chest and back
• T3: upper chest and back
• T4: upper chest (area of nipples) and back
• T5: mid-chest and back
• T6: mid-chest and back
• T7: mid-chest and back
• T8: upper abdomen and mid-back
• T9: upper abdomen and mid-back
• T10: abdomen (area of belly button) and mid-back
• T11: abdomen and mid-back
• T12: lower abdomen and mid-back

Lumbar spinal nerves

• L1: lower back, hips, groin
• L2: lower back, front and inside of thigh
• L3: lower back, front and inside of thigh
• L4: lower back, front of thigh and calf, area of knee, inside of ankle
• L5: lower back, front and outside of calf, top and bottom of foot, first four toes

Sacral spinal nerves

• S1: lower back, back of thigh, back and inside of calf, last toe
• S2: buttocks, genitals, back of thigh and calf
• S3: buttocks, genitals
• S4: buttocks
• S5: buttocks

Coccygeal spinal nerves

buttocks, area of tailbone

Dermatomes are important because they can help to assess and diagnose a variety of conditions. For instance, symptoms that occur along a specific dermatome may indicate a problem with a specific nerve root in the spine.

Examples of this include:

• Radiculopathies. This refers to conditions in which a nerve root in the spine is compressed or pinched. Symptoms can include pain, weakness, and tingling sensations. Pain from radiculopathies can follow one or more dermatomes. One form of a radiculopathy is sciatica.
• Shingles. Shingles is a reactivation of the varicella zoster (chickenpox) virus that lies dormant in the nerve roots of your body. Symptoms of shingles, such as pain and a rash, occur along dermatomes associated with the affected nerve root.

Dermatomes are areas of skin that are connected to a single spinal nerve. You have 31 spinal nerves and 30 dermatomes. The exact area that each dermatome covers can be different from person to person.

Spinal nerves help to relay information from other parts of your body to your central nervous system. As such, each dermatome transmits sensory details from a particular area of skin back to your brain.

Dermatomes can be helpful in evaluating and diagnosing conditions affecting the spine or nerve roots. Experiencing symptoms along a specific dermatome can help inform doctors about which area of the spine may be affected.

Dermatomes Diagram: Spinal Nerves and Locations

A dermatome is an area of skin supplied by a single spinal nerve. There are 31 pairs of spinal nerves, forming nerve roots that branch from your spinal cord.

Your spinal nerves help to relay sensory, motor, and autonomic information between the rest of your body and your central nervous system (CNS).

So why are dermatomes important? How many are there? And where can they be found? Continue reading as we answer these questions and more.

Each of your dermatomes is supplied by a single spinal nerve. Let’s take a closer look at both of these components of the body.

Your spinal nerves

Spinal nerves are part of your peripheral nervous system (PNS). Your PNS works to connect the rest of your body with your CNS, which is made up of your brain and spinal cord.

You have 31 pairs of spinal nerves. They form nerve roots that branch from your spinal cord. Spinal nerves are named and grouped by the region of the spine that they’re associated with.

The five groups of spinal nerves are:

• Cervical nerves. There are eight pairs of these cervical nerves, numbered C1 through C8. They originate from your neck.
• Thoracic nerves. You have 12 pairs of thoracic nerves that are numbered T1 through T12. They originate in the part of your spine that makes up your torso.
• Lumbar nerves. There are five pairs of lumbar spinal nerves, designated L1 through L5. They come from the part of your spine that makes up your lower back.
• Sacral nerves. Like the lumbar spinal nerves, you also have five pairs of sacral spinal nerves. They’re associated with your sacrum, which is one of the bones found in your pelvis.
• Coccygeal nerves. You only have a single pair of coccygeal spinal nerves. This pair of nerves originates from the area of your coccyx, or tailbone.

Your dermatomes

Each of your dermatomes is associated with a single spinal nerve. These nerves transmit sensations, such as pain, from a specific area of your skin to your CNS.

Your body has 30 dermatomes. You may have noticed that this is one less than the number of spinal nerves. This is because the C1 spinal nerve typically doesn’t have a sensory root. As a result, dermatomes begin with spinal nerve C2.

Dermatomes have a segmented distribution throughout your body. The exact dermatome pattern can actually vary from person to person. Some overlap between neighboring dermatomes may also occur.

Because your spinal nerves exit your spine laterally, dermatomes associated with your torso and core are distributed horizontally. When viewed on a body map, they appear very much like stacked discs.

The dermatome pattern in the limbs is slightly different. This is due to the shape of the limbs as compared with the rest of the body. In general, dermatomes associated with your limbs run vertically along the long axis of the limbs, such as down your leg.

Your dermatomes are numbered based on which spinal nerve they correspond to. Below, we’ll outline each dermatome and the area of the body that it’s associated with.

Remember that the exact area that a dermatome may cover can vary by individual. Some overlap is also possible. As such, consider the outline below to be a general guide.

Cervical spinal nerves

• C2: lower jaw, back of the head
• C3: upper neck, back of the head
• C4: lower neck, upper shoulders
• C5: area of the collarbones, upper shoulders
• C6: shoulders, outside of arm, thumb
• C7: upper back, back of arm, pointer and middle finger
• C8: upper back, inside of arm, ring and little finger

Thoracic spinal nerves

• T1: upper chest and back, armpit, front of arm
• T2: upper chest and back
• T3: upper chest and back
• T4: upper chest (area of nipples) and back
• T5: mid-chest and back
• T6: mid-chest and back
• T7: mid-chest and back
• T8: upper abdomen and mid-back
• T9: upper abdomen and mid-back
• T10: abdomen (area of belly button) and mid-back
• T11: abdomen and mid-back
• T12: lower abdomen and mid-back

Lumbar spinal nerves

• L1: lower back, hips, groin
• L2: lower back, front and inside of thigh
• L3: lower back, front and inside of thigh
• L4: lower back, front of thigh and calf, area of knee, inside of ankle
• L5: lower back, front and outside of calf, top and bottom of foot, first four toes

Sacral spinal nerves

• S1: lower back, back of thigh, back and inside of calf, last toe
• S2: buttocks, genitals, back of thigh and calf
• S3: buttocks, genitals
• S4: buttocks
• S5: buttocks

Coccygeal spinal nerves

buttocks, area of tailbone

Dermatomes are important because they can help to assess and diagnose a variety of conditions. For instance, symptoms that occur along a specific dermatome may indicate a problem with a specific nerve root in the spine.

Examples of this include:

• Radiculopathies. This refers to conditions in which a nerve root in the spine is compressed or pinched. Symptoms can include pain, weakness, and tingling sensations. Pain from radiculopathies can follow one or more dermatomes. One form of a radiculopathy is sciatica.
• Shingles. Shingles is a reactivation of the varicella zoster (chickenpox) virus that lies dormant in the nerve roots of your body. Symptoms of shingles, such as pain and a rash, occur along dermatomes associated with the affected nerve root.

Dermatomes are areas of skin that are connected to a single spinal nerve. You have 31 spinal nerves and 30 dermatomes. The exact area that each dermatome covers can be different from person to person.

Spinal nerves help to relay information from other parts of your body to your central nervous system. As such, each dermatome transmits sensory details from a particular area of skin back to your brain.

Dermatomes can be helpful in evaluating and diagnosing conditions affecting the spine or nerve roots. Experiencing symptoms along a specific dermatome can help inform doctors about which area of the spine may be affected.

Pinched sciatic nerve – symptoms and treatment

Pinched sciatic nerve – discomfort in the lower body associated with squeezing or irritation of the nerve itself. Most often, the disease affects people over 30 years old.

The sciatic nerve is the largest in our body. It covers most of the body – from the lumbosacral spine, then passes into the buttock, along the back of the thigh and to the lower leg. Therefore, it is important to monitor his condition. The slightest irritation in one part of the nerve will lead to pain throughout its area. In the absence of timely treatment, sensitivity and mobility of the lower extremities are gradually lost.

Pinching may occur due to:

• Lumbar hypothermia
• Excessive load on the pelvic muscles
• Scoliosis and other spinal disorders
• Injuries of the spine
• Arthrosis and other diseases of the hip joint
• Pregnancy
• Complications during childbirth
• Sedentary
• Injuries of the sciatic nerve by intramuscular injections
• Infectious diseases
• Neoplasms (benign and malignant)
• Pain when bruised or falling
• Intervertebral hernia
• Osteochondrosis
• Piriformis syndrome

Therefore, experts divide the disease into two types – primary and secondary. The primary is associated with compression of the nerve trunk by a damaged muscle, and the secondary is caused by the pathology of the spinal column, hip joints, and occurs against the background of pregnancy or diseases of the pelvic organs.

A pinched nerve can develop faster if you are overweight. It is also important to monitor the intake of essential vitamins and minerals in the body, since their absence or deficiency leads to the risk of accelerated development of the disease.

Symptoms and treatment of pinched sciatic nerve

This disease is quite painful and will not pass without a trace. Therefore, when the first symptoms appear, you should see a specialist – a neurologist, neuropathologist or therapist. He will prescribe the necessary treatment and medications.

Symptoms of a pinched sciatic nerve

• Pain in the lower back, hamstrings, buttocks or lower leg
• Discomfort while walking, when bringing the legs together and bending the knee
• Feeling of heat in the toes
• Feeling of chilliness in the affected area of ​​the nerve
• Excessive sweating
• Impaired joint mobility – usually patients complain that they cannot straighten their leg
• Numbness of limbs
• Goosebumps on the leg
• Discoloration of the skin in the affected area
• General malaise, lethargy and weakness
• Fever

It is in the presence of these symptoms that neuropathologists, neurologists and therapists diagnose a pinched sciatic nerve. If the specialist has doubts, then to fully clarify the situation, the patient is sent for CT or MRI. Based on the results of the procedures, the diagnosis and treatment will be determined.

Symptoms in women with pinched sciatic nerve

The disease can occur during pregnancy. In the second or third trimester, the enlarged uterus puts pressure on the pelvic muscles, thereby causing a spasm. In the expectant mother, the center of gravity is redistributed and the lumbar vertebrae are displaced. Also in the pelvic area, the growing head of the fetus compresses the sciatic nerve.

From 40 to 80% of pregnant women complain of back pain. However, pinching of the sciatic nerve is not always the cause, it is observed only in 5% of cases.

Doctors say that the disease can go away after childbirth. However, you should not endure pain until this moment, it is better to see a specialist in order to avoid serious consequences and increase pain.

Treatment of pinched sciatic nerve

Most of the time, the pain comes on suddenly. Therefore, before contacting a specialist, you need to take a few simple steps:

1. Sit in a comfortable and pain-free position. The best option is to lie on your back or on your healthy side with a straight leg in which pain is felt

2. Avoid activity as much as possible, as each extra movement can provoke additional pain

3. Give up old-fashioned methods of treatment – it is better to put the heating pad aside, and do not rub the diseased area. These actions may aggravate the situation

4. Take painkillers. They will help dull the sharp aching pain. Usually such preparations are in the form of capsules or ointments

Emergency medical attention should be called for unbearable pain that is not dulled or suppressed by analgesics. In more favorable cases, medical assistance is also needed. It is best to contact a neurologist, neurologist or therapist. As soon as the pain is relieved, see a doctor at a local clinic.

How is a pinched sciatic nerve treated?

After asking about symptoms and examining, the doctor refers the patient to an X-ray, ultrasound, CT, MRI, or a general and biochemical blood test. Procedures are necessary in order to determine the extent of the problem. Also, based on their results, the doctor determines the cause of the pinched sciatic nerve and detects inflammation.

After that, experts prescribe anti-inflammatory drugs, a complex of B vitamins and muscle relaxants. Also, the patient can receive a referral to physiotherapy and exercise therapy. Usually, procedures are prescribed for unbearable pain that does not go away even after complex treatment. In special cases, the doctor may prescribe additional vitamin complexes, antioxidants and painkillers. Thus, not only the symptoms of the disease will be removed, but the fight against the disease-causative agent will also begin.

In addition, specialists also prescribe sanatorium-resort treatment, which includes balneological procedures, for example, mud therapy.

When the sciatic nerve is pinched, doctors rarely turn to surgical intervention. In this case, the indications will be advanced forms of osteochondrosis that are not amenable to therapy, or volumetric processes in the affected area – tumors or abscesses.

Sciatica of the sciatic nerve: symptoms, treatment, diagnosis of the disease

Sciatica of the sciatic nerve is an inflammatory disease, which, according to the degree of discomfort it causes, is included in the list of the most painful human pathologies. The sciatic nerve is the largest nerve fiber in the human body, connecting the spinal column to the lower limb. It starts in the lumbar region and ends in the phalanges of the toes. It is a paired organ present in both lower extremities. When the nerve fiber is compressed, severe pain occurs, which is localized in the sacrum, spreads to the buttock, femoral part and lower down to the foot.

Symptoms of the disease

The most important symptoms of sciatica of the sciatic nerve are:

• pain localized in any part of the body along the passage of the nerve fiber: in the lower back, buttock, back of the thigh, lower leg, foot;
• loss of sensation, numbness of the lower limb along the nerve fiber;
• paresthesia – tingling sensations, “goosebumps” in the foot and toes.

The nature of the pain is most often shooting, but it can also be burning, dull, aching, etc. During periods of exacerbation, with movements of the spine or leg, it can intensify and become unbearable. As a rule, the disease affects one limb, but sometimes the pain appears in both legs at once. In the most severe cases, the disease leads to paralysis of the muscles of the leg, sometimes spreading to the muscles of the small pelvis, causing urinary and fecal incontinence in the patient.

Causes

Sciatica of the sciatic nerve is a disease that can be caused by a number of causes of a vertebrogenic, i. e. associated with the spine, or non-vertebrogenic nature.

• Compression of the sciatic nerve or its branches is the most common cause of pain due to deformity, herniated disc, inflammation of the piriformis muscle, or displacement of a vertebra.⁠
• Injuries to the lower spine, pelvis, or limb can result in nerve compression and nerve damage.
• Degenerative-dystrophic changes in the structure of the spine – osteochondrosis, spondylarthrosis – lead to compression of the sciatic nerve.
• Infectious diseases – scarlet fever, influenza, malaria, etc. – are accompanied by the release of toxins, leading to inflammation of the nerve fiber.
• Toxins that enter the body from the outside – at work, when drinking alcoholic beverages – can also cause inflammation.
• Systemic diseases – diabetes, gout, etc. – become the background for the appearance of pain.
• A malignant or benign tumor that compresses a nerve is another likely cause of the pathology.
• Hypothermia or excessive physical activity sometimes become the beginning of the inflammatory process.

Some experts single out the psychosomatics of sciatic nerve sciatica as a separate group of causes, believing that the disease can develop against the background of excessive psychological stress, stress, chronic fatigue, fear or phobia.

Diagnosis

This disease is characterized by a rather complicated diagnosis, the first stage of which is the conduct of reflexological tests for flexion and extension of the leg. To finally clarify the clinical picture, as necessary, appoint:

• laboratory tests;
• radiography of the affected area;
• MRI;
• CT;
• electroneuromyography;
• Ultrasound of the pelvic region.

The task of a neurologist is to identify symptoms characteristic of sciatica, and treatment should be aimed at eliminating the causes of nerve fiber compression.

Treatment

The choice of therapeutic methods depends on how severe the clinical manifestations of the disease are. When first contacting a neurologist, conservative methods of treating sciatica of the sciatic nerve prevail:

• non-steroidal anti-inflammatory drugs;
• hormonal preparations for the most severe cases;
• analgesics to relieve pain;
• antispasmodics, muscle relaxants.

Great importance is attached to all kinds of physiotherapeutic methods, which are used both during exacerbations (UHF, electrophoresis, laser or magnetic therapy), and at their end.

Massage for sciatica is of great benefit, significantly prolonging the periods of remission. Depending on the nature of the squeezing factor, the patient may be prescribed a general massage to relax the spinal muscles, therapeutic, acupressure or cupping. In many cases, acupuncture sessions bring considerable benefits.

Therapeutic exercises for sciatica is another extremely useful technique that is widely used after the acute phase of the disease. Moderate physical activity aimed at strengthening the muscular corset and improving the blood supply to the tissues of the back, pelvis and limbs allows patients to maintain their body in good physical shape and prevent the recurrence of pain attacks.

Statistics

Sciatica of the sciatic nerve is a fairly common disease in the age group from 35 to 50 years. It is the most active age that accounts for the majority of primary visits to the doctor. The disease affects men more often than women. According to some experts, during the whole life, up to 40% of people have experienced at least once an attack of pain in the sacral part of the lower back, buttock or back of the thigh, but not all of these attacks become chronically protracted. Cases of visiting a doctor are about 20-25 people per 100 thousand of the population.

Diagnostics and treatment of sciatica of the sciatic nerve in Moscow

JSC “Medicina” invites Muscovites and guests of the capital for consultations on the diagnosis and treatment of sciatica of the sciatic nerve. At your service – the most modern diagnostic and physiotherapy equipment, as well as the qualifications and experience of medical personnel. In our clinic, neurologists and orthopedists of the highest category are treated, who will be able to relieve pain in the shortest possible time and return you to a full life. Call us to make an appointment with a specialist, or leave a request online on our website.

Questions and answers

Which doctor treats sciatica of the sciatic nerve?

If pain occurs, you should immediately contact a qualified neurologist in order to carry out the necessary diagnostic procedures and determine the best method for treating sciatica sciatica.

How to sleep with sciatica of the sciatic nerve?

Severe pain often interferes with healthy sleep. To reduce the likelihood of their occurrence, it is necessary to take care of an orthopedic mattress of moderate softness, on which the back will maintain a natural deflection during sleep.