What are dermatomes. How do they relate to spinal nerves. Which medical conditions can affect dermatomes. How do doctors use dermatome knowledge in diagnosis.

The Fundamentals of Dermatomes: Mapping Skin Sensation

Dermatomes play a crucial role in our body’s sensory system, acting as specific areas of skin that transmit signals to the brain through spinal nerves. This intricate network covers the entire body, from the fingertips to the toes, creating a comprehensive map of sensory information. But what exactly are dermatomes, and how do they function?

A dermatome is essentially a region of skin innervated by a single spinal nerve. These nerves exit the spine in pairs, with 31 pairs in total. Interestingly, 30 of these pairs correspond to dermatomes, with the C1 spinal nerve being the exception. The spinal nerves are categorized into five groups based on their exit points from the spine:

• Cervical nerves (C1-C8): Exiting from the neck region
• Thoracic nerves (T1-T12): Exiting from the torso region
• Lumbar nerves (L1-L5): Exiting from the lower back region
• Sacral nerves (S1-S5): Exiting from the base of the spine
• Coccygeal nerve pair: Exiting from the tailbone or coccyx

Each dermatome shares the label of its corresponding spinal nerve, creating a systematic way to identify and map these sensory areas. It’s important to note that dermatomes can overlap to some extent, and their precise layout may vary slightly between individuals.

Dermatome Distribution: A Comprehensive Body Map

Understanding the distribution of dermatomes throughout the body is essential for medical professionals and can be fascinating for anyone interested in human anatomy. How are dermatomes arranged across different body regions?

Cervical Dermatomes (C2-C8)

The cervical dermatomes cover the head, neck, and upper extremities:

• C2: Base of the skull, behind the ear
• C3: Back of the head and upper neck
• C4: Lower neck and upper shoulders
• C5: Upper shoulders and collarbones
• C6: Upper forearms, thumbs, and index fingers
• C7: Upper back, backs of the arms, and middle fingers
• C8: Upper back, inner arms, ring and pinky fingers

Thoracic Dermatomes (T1-T12)

The thoracic dermatomes are responsible for sensation in the chest, upper abdomen, and mid-back areas:

• T1: Upper chest, back, and upper forearm
• T2-T4: Upper chest and back
• T5-T7: Mid-chest and back
• T8-T9: Upper abdomen and mid-back
• T10: Midline of the abdomen and mid-back
• T11-T12: Lower abdomen and mid-back

Lumbar Dermatomes (L1-L5)

The lumbar dermatomes cover the lower back, hips, and legs:

• L1: Groin, upper hips, and lower back
• L2: Lower back, hips, and tops of inner thighs
• L3: Lower back, inner thighs, and inner legs just below the knees
• L4: Backs of knees, inner sections of lower legs, and heels
• L5: Tops of feet and fronts of lower legs

Sacral Dermatomes (S1-S5)

The sacral dermatomes are responsible for sensation in the lower extremities and genital area:

• S1: Lower back, buttocks, backs of legs, and outer toes
• S2: Buttocks, genitals, backs of legs, and heels
• S3: Buttocks and genitals
• S4-S5: Buttocks

Coccygeal Dermatome

The coccygeal nerves correspond to a dermatome located on the buttocks, specifically in the area directly surrounding the tailbone or coccyx.

Clinical Significance: Dermatomes as Diagnostic Tools

Dermatomes serve a crucial role in medical diagnosis and treatment. How do healthcare professionals utilize dermatome knowledge in clinical settings?

Symptoms occurring within a specific dermatome can indicate damage or disruption to the corresponding nerve. This localization of symptoms helps doctors diagnose underlying medical conditions more accurately. By identifying the affected dermatome, healthcare providers can pinpoint which spinal nerve might be involved, leading to more targeted diagnostic procedures and treatments.

For instance, if a patient complains of pain or sensory changes in a particular area of the body, a doctor can use their knowledge of dermatomes to narrow down which nerve root might be affected. This information can guide further investigations, such as imaging studies or nerve conduction tests, to confirm the diagnosis and determine the appropriate treatment plan.

Health Conditions Affecting Dermatomes: From Shingles to Nerve Compression

Several health conditions can impact the spinal nerves and their corresponding dermatomes. Understanding these conditions is crucial for both medical professionals and patients. Which medical issues commonly affect dermatomes?

Shingles (Herpes Zoster)

Shingles is a viral infection caused by the reactivation of the varicella-zoster virus, the same virus responsible for chickenpox. After recovering from chickenpox, the virus can remain dormant in the body and later reactivate as shingles.

In adults, shingles typically manifests as a rash along one of the thoracic dermatomes on the trunk. The rash is often preceded by pain, itching, or tingling in the affected area. Other symptoms may include:

• Headache
• Sensitivity to bright light
• General feeling of being unwell

In individuals with weakened immune systems, shingles can develop into a more widespread rash covering three or more dermatomes, a condition known as disseminated zoster.

Pinched Nerves

A pinched nerve occurs when a nerve root is compressed by surrounding structures such as bones, discs, tendons, or ligaments. While this compression can happen anywhere along the spine, it most commonly affects the lumbar region.

Pinched nerves can cause pain, tingling, or numbness in the corresponding dermatome. The location of these symptoms helps doctors identify the affected nerve, guiding their diagnosis and treatment approach. Treatment typically involves addressing the underlying cause of the nerve compression and providing symptomatic relief.

Traumatic Injury

Traumatic injuries to nerves can result from accidents or surgical procedures. The severity of symptoms can vary depending on the extent of the nerve damage and the specific dermatome affected. Proper diagnosis and timely intervention are crucial for managing these injuries and promoting optimal recovery.

Diagnostic Techniques: Leveraging Dermatome Knowledge

How do medical professionals use their understanding of dermatomes in diagnostic procedures? The knowledge of dermatome distribution plays a vital role in various diagnostic techniques and assessments.

Physical Examination

During a physical examination, doctors may test sensory function in different dermatomes using various stimuli such as light touch, pinprick, or temperature. By systematically assessing sensation across dermatomes, they can identify areas of altered sensation that may indicate nerve root involvement.

Imaging Studies

When a specific dermatome is implicated based on a patient’s symptoms, imaging studies can be targeted to the corresponding spinal level. This might include X-rays, CT scans, or MRI scans to visualize potential causes of nerve compression or irritation.

Electromyography (EMG) and Nerve Conduction Studies

These tests can help assess the function of specific nerves and muscles. By correlating the results with dermatome patterns, doctors can gain valuable insights into the location and extent of nerve involvement.

Treatment Approaches: Tailoring Interventions to Affected Dermatomes

Understanding dermatomes not only aids in diagnosis but also informs treatment strategies. How do healthcare providers use dermatome knowledge to guide therapeutic interventions?

Targeted Pain Management

For conditions like shingles or pinched nerves, pain management can be tailored to the specific dermatome affected. This might involve topical treatments, nerve blocks, or other localized interventions aimed at providing relief to the affected area.

Surgical Planning

In cases requiring surgical intervention, such as for severe nerve compression, knowledge of dermatomes helps surgeons plan their approach. They can target the specific spinal level corresponding to the affected dermatome, minimizing unnecessary tissue disruption.

Rehabilitation Strategies

Physical therapists and occupational therapists use dermatome maps to guide their treatment plans. They can design exercises and interventions that target specific muscle groups and sensory areas corresponding to affected dermatomes, promoting optimal recovery and function.

Advanced Concepts: Dermatome Overlap and Variability

While dermatome maps provide a valuable framework for understanding sensory distribution, it’s important to recognize that the reality is often more complex. How do dermatomes interact and vary between individuals?

Dermatome Overlap

Dermatomes are not always distinctly separated but can overlap to varying degrees. This overlap means that a single area of skin might receive sensory input from multiple spinal nerves. As a result, damage to a single nerve root may not always result in complete sensory loss in the corresponding dermatome.

Individual Variability

The precise layout of dermatomes can vary slightly from person to person. This individual variability underscores the importance of comprehensive clinical assessment rather than relying solely on standardized dermatome maps.

Neuroplasticity and Sensory Remapping

In cases of nerve injury or chronic pain conditions, the brain’s ability to reorganize neural pathways (neuroplasticity) can lead to changes in sensory perception. This neuroplasticity can sometimes result in alterations to the typical dermatome pattern, further highlighting the complexity of the sensory nervous system.

Understanding these nuances in dermatome distribution and function is crucial for healthcare professionals. It allows for a more accurate interpretation of clinical findings and helps in developing personalized treatment strategies that account for individual variations in sensory innervation.

Dermatomes: Definition, chart, and diagram

Dermatomes are areas of skin that send signals to the brain through the spinal nerves. The dermatome system covers the entire body from the hands and fingers to the feet and toes.

The part of a nerve that exits the spinal cord is called the nerve root. Damage to a nerve root can trigger symptoms in the nerve’s corresponding dermatome.

Below, we show the locations of the dermatomes throughout the body. We also describe health conditions that can damage the spinal nerves and affect their dermatomes.

Share on PinterestVarious health problems damage the spinal nerves and affect the surrounding skin.

A dermatome is an area of skin that sends information to the brain via a single spinal nerve.

Spinal nerves exit the spine in pairs. There are 31 pairs in total, and 30 of these have corresponding dermatomes.

The exception is the C1 spinal nerve, which does not have a corresponding dermatome.

The spinal nerves are classified into five groups, according to the region of the spine from which they exit.

The five groups and their points of exit from the spine are:

1. Cervical nerves: These exit the neck region and are labeled C1–C8.
2. Thoracic nerves: These exit the torso region and are labeled T1–T12.
3. Lumbar nerves: These exit the lower back region and are labeled L1–L5.
4. Sacral nerves: These exit the base of the spine and are labeled S1–S5.
5. A coccygeal nerve pair: These exit the tailbone, or coccyx.

Each dermatome shares the label of its corresponding spinal nerve.

Some dermatomes overlap to a certain extent, and the precise layout of the dermatomes can vary slightly from one person to the next.

Below, we list the locations of the dermatomes that correspond to the spinal nerves in each group.

Cervical nerves and their dermatomes

• C2: the base of the skull, behind the ear
• C3: the back of the head and the upper neck
• C4: the lower neck and upper shoulders
• C5: the upper shoulders and the two collarbones
• C6: the upper forearms and the thumbs and index fingers
• C7: the upper back, backs of the arms, and middle fingers
• C8: the upper back, inner arms, and ring and pinky fingers

Thoracic nerves and their dermatomes

• T1: the upper chest and back and upper forearm
• T2, T3, and T4: the upper chest and back
• T5, T6, and T7: the mid-chest and back
• T8 and T9: the upper abdomen and mid-back
• T10: the midline of the abdomen and the mid-back
• T11 and T12: the lower abdomen and mid-back

Lumbar nerves and their dermatomes

• L1: the groin, upper hips, and lower back
• L2: the lower back, hips, and tops of the inner thighs
• L3: the lower back, inner thighs, and inner legs just below the knees
• L4: the backs of the knees, inner sections of the lower legs, and the heels
• L5: the tops of the feet and the fronts of the lower legs

Sacral nerves and their dermatomes

• S1: the lower back, buttocks, backs of the legs, and outer toes
• S2: the buttocks, genitals, backs of the legs, and heels
• S3: the buttocks and genitals
• S4 and S5: the buttocks

The coccygeal nerves and their dermatome

The dermatome corresponding with the coccygeal nerves is located on the buttocks, in the area directly around the tailbone, or coccyx.

Symptoms that occur within a dermatome sometimes indicate damage or disruption to the dermatome’s corresponding nerve. The location of these symptoms can, therefore, help doctors diagnose certain underlying medical conditions.

Some conditions that can affect the nerves and their corresponding dermatomes are:

Shingles

Shingles, or herpes zoster, is a viral infection caused by the reactivation of the varicella-zoster virus. This is the same virus that causes chickenpox.

After the body recovers from chickenpox, the virus can lie dormant and eventually reactivate as shingles.

In adults, shingles typically causes a rash to form on the trunk, along one of the thoracic dermatomes. The rash may be preceded by pain, itching, or tingling in the area.

Some other symptoms of shingles can include:

• a headache
• sensitivity to bright light
• a general feeling of being unwell

A person with a weakened immune system may develop a more widespread shingles rash that covers three or more dermatomes. Doctors refer to this as disseminated zoster.

Pinched nerves

A pinched nerve occurs when a nerve root has become compressed by a bone, disc, tendon, or ligament. This compression can occur anywhere along the spine, but it usually occurs in the lower, or lumbar, region.

A pinched nerve can cause pain, tingling, or numbness in its corresponding dermatome. As such, the location of the symptoms can help a doctor identify the affected nerve.

The doctor then diagnoses and treats the underlying cause of the pinched nerve and recommends ways to relieve the symptoms.

Traumatic injury

A traumatic injury to the nerves may result from an accident or surgery.

The severity of symptoms can help doctors determine the extent of the nerve injury.

Dermatomes are areas of skin, each of which is connected to a single spinal nerve. Together, these areas create a surface map of the body.

Dysfunction or damage to a spinal nerve can trigger symptoms in the corresponding dermatome. Nerves damage or dysfunction may result from infection, compression, or traumatic injury.

Doctors can sometimes use the severity of symptoms in a dermatome to determine the extent and location of nerve damage. They then work to diagnose and treat the underlying cause of the damage.

Dermatomes | HiTech Therapy Online

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High-quality Anatomical Charts that deliver a clear, accurate view of the human body and all its systems. Dynamic full-colour artwork illustrates the cutaneous areas of peripheral nerve innervation and the development of dermatomes.

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Manufacturer: Synergy

SKU: 9936

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This dermatomes poster defines the human dermatomes in beautiful colour illustrations. Dermatomes provide a way to map the approximate areas of skin on the body that is supplied by nerves from a single spinal root. 

Features:

• cutaneous areas of peripheral nerve innervation and corresponding dermatome (main image)
• definition of a dermatome
• the spinal cord with dorsal root ganglion
• the development of dermatomes
• dermatomes in extremities.

All important structures are numbered and/or labelled, making this detailed dermatomes chart is ideal for physiotherapy or other health students learning anatomy. The chart may also be useful for explaining the concept of dermatomes to patients.

This dermatomes poster has been laminated to ensure that it will be long-lasting, and the poster can be written on and wiped off with non-permanent markers.

Size: 51cm (W) x 66cm (L)

Nappi Code: None

This dermatomes poster defines the human dermatomes in beautiful colour illustrations. Dermatomes provide a way to map the approximate areas of skin on the body that is supplied by nerves from a single spinal root. 

Features:

• cutaneous areas of peripheral nerve innervation and corresponding dermatome (main image)
• definition of a dermatome
• the spinal cord with dorsal root ganglion
• the development of dermatomes
• dermatomes in extremities.

All important structures are numbered and/or labelled, making this detailed dermatomes chart is ideal for physiotherapy or other health students learning anatomy. The chart may also be useful for explaining the concept of dermatomes to patients.

This dermatomes poster has been laminated to ensure that it will be long-lasting, and the poster can be written on and wiped off with non-permanent markers.

Size: 51cm (W) x 66cm (L)

Nappi Code: None

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What are dermatomes and where are they

Dermatomes are specific areas of the body innervated by a nerve exiting the spine. The spine is made up of 33 vertebrae and 31 pairs of nerves that are organized throughout the body.

Each nerve that exits the spine is responsible for imparting sensation and strength to a particular area of ​​the body, so whenever a nerve is compressed or cut, that particular area of ​​the body is endangered. In this way, it is possible to determine which part of the spinal cord has been affected by compression, trauma, or a herniated disc, such as when a person says they feel tingling, weakness, or an inability to move their arm or side of the foot.

There are 31 dermatomes in total, which are sort of divided into “slices”, as shown in the following image:

Map of body dermatomes and myotomes

Map of body dermatomes

The best way to identify all dermatomes in the body is to observe a person standing on four supports, because it is easier to perceive “cuts” this way. The following are the main dermatomes of the body:

• Cervical dermatomes – face and neck : they are specially innervated by a nerve emerging from C1 and C2 vertebrae;
• Thoracic dermatomes – Chest : these are areas weakened by nerves that arise from the vertebrae T2 to T12;
• Dermatomes of the upper limbs – Arms and hands : innervated by nerves from the vertebrae C5 to T2;
• Dermatomes of the lumbar and lower extremities – Legs and feet : contain areas innervated by nerves that emerge from the vertebrae L1 to S1;
• Buttocks: is the area innervated by the nerves in the sacrum, from S2 to S5.

The dermatome map is commonly used by physicians and physiotherapists to detect changes or pressures in the spinal cord, because if there is a change in sensation in a certain area of ​​the body, it is easier to determine where the spine is at risk, for example, an injury or a herniated disc.

But in addition, dermatomes can also be used in alternative therapies, such as acupuncture or reflexology, to directly stimulate certain areas of the spinal cord or other organs innervated by the corresponding pair of nerves. Thus, an acupuncturist can insert a needle into the spine to relieve pain and discomfort in other parts of the body.

Map of dermatomes at 4 supports

Difference between dermatome and myotome

Dermatomes refer to sensory changes in the skin and myotomes are responsible for muscle movement in the same area. The table below shows some examples:

900 49 L2

9 0049 Flex forearm and extend wrist

Thus When a person has a sensation of numbness on the side of the foot, it is most likely that a change will occur in the spine, and more specifically between the L5 and S1 vertebrae, because this is their dermatome. But when he has weakness and difficulty in bending his arm, the affected area is the cervical region, specifically C6 and C7, because that area is his myotome.

Split Skin Flap Transplantation – Innovative Vascular Center

Skin grafting using a split skin flap is the easiest way to heal large wound surfaces. To close wounds on the leg, a split skin flap is taken mainly from the surface of the thigh or buttocks.

The meaning of this free skin grafting is to use a thin 0.1-0.8 mm surface layer of the skin, which is taken with a special instrument by a dermatome. This skin flap is perforated, which makes it possible to increase its area by several times and close even large skin defects.

After that, it is placed on the previously prepared perceiving wound and fixed with separate sutures. As a result of the operation, the transplanted skin grows into the wound and closes it. The area where the skin was taken from heals on its own, as the growth part of the skin remains in place.

Benefits of treatment at the Innovative Vascular Center

Compared to other clinics in our country, the Innovative Vascular Center has undeniable advantages in the use of plastic surgery methods for the treatment of vascular patients. In our clinic, the closure of skin wounds and trophic ulcers is performed in a specialized department for the treatment of critical ischemia. Wounds are treated by surgeons who ensure the restoration of blood circulation before plastic surgery, which is necessary for successful wound healing.

We are well aware of the course of wound processes in patients, and we choose the necessary time and method for closing a trophic ulcer or wound for each case. To prepare wounds for skin grafting, we use methods of active preparation of the wound surface. Dressings and antibacterial drugs are prescribed taking into account the sensitivity of the wound microflora.

Thanks to innovative technologies, we manage to heal such wounds that no other clinic in our country takes on!

Preparation for treatment

Before skin plastic surgery, a number of conditions must be met. The human body must be stabilized in terms of blood, protein synthesis. It is necessary to stop the infectious process. Conditions for skin grafting should be local:

• Good bleeding of the wound edges, active juicy granulations.

• The wound is in the granulation stage (without signs of active infection and purulent inflammation).

• The ulcer must be well supplied with blood (circulation must first be restored).

• The defect must be cleaned of dead tissue using physical and chemical methods.

General conditions for skin plastic surgery:

• The level of protein in the blood should be at least 60 g / liter.

• Hemoglobin level is at least 90 g/litre.

• Before transplantation, the patient must be stabilized in general condition.

Direct preparation for the operation involves shaving the site of skin flap sampling, catheterization of the bladder, and installation of an epidural catheter for anesthesia.

Pain relief

During operations on the extremities, epidural or spinal anesthesia is mainly used. Their advantage lies in the local effect on the body. Epidural anesthesia allows prolonged pain relief after surgery.

In order to control the functions of the cardiovascular system, a special monitor is connected to the patient to monitor systemic hemodynamics.

How skin plastic surgery is performed

First, markup and planning is carried out. To close the defect, the skin flap is taken slightly less than the area of ​​the ulcer, because perforations allow it to be stretched. The patient is placed on the operating table so that there is good access to the wound. After processing the surgical field and closing the operation area with sterile sheets, the trophic ulcer is treated surgically. During this treatment, all remaining necrotic tissue areas are removed and pinpoint bleeding from the granulations is provided.

After that, a split skin flap is taken with a dermatome. The technology is pretty simple. A saline solution is injected into the thickness of the skin, which lifts the skin itself and facilitates its separation. After creating such a “water cushion”, the flap is taken using a special tool – an electrodermotomy. This is a special disc knife, which is set to a certain thickness of the required flap for transplantation. After that, the razor of this dermatome removes the thinnest skin flap of the right size.

To increase the area of ​​the skin flap, it is passed through a special tool – a perforator. The perforator in a checkerboard pattern makes small cuts on the flap. Now the flap, when stretched, can cover an area several times larger than its original one.

After perforation, the flap is placed on the wound surface and modeled according to the shape of the defect. In order to fix it, it is mainly sutured with the thinnest sutures to the edges of the wound and pressed with a pressure bandage. Although you can simply place the flap along the contour of the defect and straighten it with tweezers without fixation. The donor site is treated with an antiseptic and closed with a contour bandage with iodopyrone.

Postoperative period

The first dressing after flap transplantation is preferably done 2-3 days after the operation. During this time, most of the flap adheres to the granulation tissue and does not come off when the dressing is changed. The dressing must be changed very carefully, removing it in layers with the help of a tool. Mesh materials (branolind, waxopran) are used to protect the flap from granulation.

During dressing, fixation of the transplanted flap to the granulations is noted, and non-adhering pieces of skin are removed. If there is a local infection, then you need to take a crop and use dressings with antiseptics.

After transplantation, the bandage at the donor site can not be opened if there are no signs of infection. It is enough to change the bandage on top. Over time, the skin epithelializes and the bandage will come off by itself. Usually 14 – 21 days after surgery.

Forecast

If the operation is performed according to indications, provided that the causes of necrosis and trophic ulcers are eliminated, then the results of skin plastic surgery are very good. Correctly performed operation ends with success in 95% of cases. In the postoperative period, the transplanted skin is gradually replaced by its own epidermis, which manifests itself in the appearance of small crusts, under which young skin is visible. The healed defect is treated with a nourishing vitamin cream until complete structural restoration.

Autodermoplasty may be the definitive method of wound closure if the ulcer is not located on the supporting surface or in the area of ​​a large joint. In such places, young skin can be damaged by stress with the formation of trophic ulcers. For supporting and bone surfaces, it is better to use full-layer skin grafting with flaps on a vascular pedicle.

Surveillance program

The operating surgeon must observe the patient until the complete epithelialization of the trophic ulcer on which the skin was transplanted.