German Contact Help Login Register

Dermatomes

Contents

Overview

The dermatomes is a word of greek origin which means ‘areas of skin’. Dermatomes are indeed specific theoretical areas upon the human body that are derived from the cells of a certain somite. The areas are spread out according to the dominant spinal nerve that happens to innervate it.

Recommended video: Structure of spinal cord
Full structure of the spinal cord seen from a dorsal view.

The spinal cord has thirty one segments, each with its own bilateral anterior and posterior pair of nerve roots that innervate the anatomical structures with motoric and sensory fibers. The clinical significance of a dermatome is that when a dermatological case presents itself, a rash for example, that is limited to a single dermatome, that outer clinical symptom may indicate the pathological involvement of its related spinal root.

Dermatome Test Points

A system of points on the body within the region of a dermatome has been devised so that those without direct access to a dermatome map have the ability to localise the pain and correctly diagnose the nerve that may be affected. Here is a list of the dermatome test points, organized by the spinal root that governs each dermatome, along with an approximation of the area that it covers. The list runs through the spinal nerves in a cranial to caudal direction.

Upper Body

  • C2 - Occipital Protuberance
  • C3 - Supraclavicular Fossa
  • C4 - Acromioclavicular Joint
  • C5 - Lateral Antecubital Fossa
  • C6 - Thumb
  • C7 - Middle Finger
  • C8 - Little Finger
  • T1 - Medial Antecubital Fossa
  • T2 - Apex of the Axilla

Lower Body

  • L1 - Upper Anterior Thigh
  • L2 - Mid Anterior Thigh
  • L3 - Medial Femoral Condyle
  • L4 - Medial Malleolus
  • L5 - Dorsum of the third Metacarpal Joint
  • S1 - Lateral Heel
  • S2 - Popliteal Fossa
  • S3 - Ischial Tuberosity
  • S5 - Perianal Area

Face

There are three other dermatome test points that are governed not by the spinal roots but the trigeminal nerve (CN V). The three trigeminal divisions are responsible for the innervation of the face.

Get me the rest of this article for free
Create your account and you’ll be able to see the rest of this article, plus videos and a quiz to help you memorize the information, all for free. You’ll also get access to articles, videos, and quizzes about dozens of other anatomy systems.
Create your free account ➞
Show references

References:

Author:

  • Dr. Alexandra Sieroslawska
© Unless stated otherwise, all content, including illustrations are exclusive property of Kenhub GmbH, and are protected by German and international copyright laws. All rights reserved.

Continue your learning

Article (You are here)
Other articles
Well done!
Create your free account.
Start learning anatomy in less than 60 seconds.