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Dermatomes (cont.)

How Are Dermatomes Used by Medical Professionals?

Because the distribution pattern of the spinal nerve dermatomes is so defined, the dermatomes can be used to detect the area or location that causes the sensation of abnormalities along its location in the human body. For example:

  • If a patient had sciatica (nerve pain from the irritation of the largest nerve in the body, the sciatica nerve) with signs and symptoms of low back pain and numbness and tingling on top of the right foot, the doctor could recognize this as a problem with the nerve that comes out below the right side of the fifth lumbar vertebra (L5) and disc. The most common cause of this particular medical situation would be a rightward herniation of the disc beneath the fifth lumbar vertebra (L5).
  • If a patient is experiencing numbness and tingling down the right arm to the thumb (limb), index and middle finger (the C6,7,8 dermatome spinal nerves), the doctor must consider abnormalities that can affect the spinal nerves coming from the C6,7,8 nerve roots. This could be caused by abnormalities in the spinal cord or discs or vertebrae (C6-C8) or anywhere along the distribution of the nerve through the right upper limb (arm or hand).

The location of dermatomes on the skin can be used on a patient to precisely pinpoint the area that is the cause of many medical conditions and illness because their distribution is precisely located in the same areas in every human. For example:

  • Shingles is an outbreak of a virus that inflamed the spinal nerve along a specific skin dermatome. It is relatively easily identifiable with signs and symptoms of a painful, red, blistering rash on the skin that tracks along a specific dermatome on one side of the body (right or left). Moreover, the intense itching and potentially chronic pain that a patient may experience with shingles is precisely located in the identical skin dermatome distribution.

Dermatomes also can be used by medical professionals to assess and diagnosis the exact level of spinal cord or nerve injury in in a patient with spinal cord trauma, such as from a motor vehicle accident or diving. They also are used by medical professionals in anesthesiology when epidural blocks are given to patients for pain. The doctor can determine when the block is effectively blocking the nerve by noted lack of sensation (for example, pain, numbness, and tingling) in the dermatome distribution of the particular level in the spine where the anesthetic was injected into the patient.


Kishner, S., MD. "Dermatomes Anatomy." Medscape. Updated: Aug 15, 2015.

Medically Reviewed by a Doctor on 8/31/2017

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