Dermatome map — map of nerve pathways to diagnose spine conditions

A dermatome map is a map of the nerve patterns of the skin. For patients with a compressed nerve in the spinal cord and only symptoms of radiating pain, a dermatome map is a useful tool to locate the root location of the impacted nerve.

For many people suffering from chronic pain in the extremities, the dermatome map can help a physician locate the source of the pain to determine the next steps for treatment. For example, if the source of the pain is located back to the lumbar spine (lower back), the physician might order an MRI test for a more in-depth evaluation of the nerve damage in the lower back and what is causing the condition. Using a dermatome map helps a physician narrow the scope of search when a patient is only experiencing radiating pain in the extremities and not local pain at the site of the condition.

Process of a dermatome map

A dermatome map allows a physician to view the nerve pathways from a nerve to the different extremities associated with that nerve. For example, if a physician followed the path of the C8 nerve pathway, the pathway would lead from the back of the shoulder, through the armpit and into the pinky finger. Therefore, if a patient states that he is experiencing pain in the arm and into the pinky finger, the physician can trace that pain to a nerve in the upper back.

At that point, the physician can run a series of tests to determine the next step for the patient, which would most likely involve an MRI test and an appointment with a chiropractor or massage therapist to try to relax the nerve.

Dermatome maps correspond to the levels of the spine. Listed from top to bottom in relation to location on the spine, the spinal levels are called the cervical ( C ), thoracic ( T ), lumbar ( L ) and sacral ( S ) levels.

Some examples of dermatomes and their corresponding spinal levels are:

  • Middle and sides of calves — L4 and L5
  • Little toes — S1
  • Fronts of thighs — L2
  • Inner and outer forearms — C6 and T1
  • Shoulders — C4 and C5
  • Thumbs and little fingers — C6, C7 and C8

If you would like to learn more about the spine conditions associated with specific nerves and areas of the spine, please contact our care team at Laser Spine Institute. We are here to help you determine the treatment options available to you based on your spine condition and medical history.