Dermatomic area
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Dermatomic area (also known as a dermatome) is an area of skin that is supplied by a single pair of dorsal roots. An area innervated by peripheral nerves is a peripheral nerve field.
The body can be divided into regions that are mainly supplied by a single spinal nerve. There are eight cervical (one for the head, and one for each cervical vertebra), twelve thoracic, five lumbar and five sacral spinal nerves.
This innervates the body in a patterned form. Along the thorax and abdomen it is simply like a stack of discs forming a human, each supplied by a different spinal nerve.
Along the arms and the legs, the pattern is different: the dermatomes run longitudinally along the limbs.
Clinical significance
Dermatomes are useful in neurology for finding the site of damage to the spine.
Herpes zoster infections (shingles) can reveal dermatomic areas. Herpes zoster, a virus that is dormant in the dorsal root ganglion, migrates along the spinal nerve to affect only the area of skin served by that nerve. Symptoms can be bilateral and symmetric, meaning that the virus is present in both ganglia of a dorsal root ganglion pair.
Additional images
 Distribution of cutaneous nerves. Ventral aspect. |
 Distribution of cutaneous nerves. Dorsal aspect. |
 Cutaneous nerves of right upper extremity. Anterior view. |
Gray812.svg
Diagram of segmental distribution of the cutaneous nerves of the right upper extremity. Anterior view. |
 Cutaneous nerves of right upper extremity. Posterior view. |
 Diagram of segmental distribution of the cutaneous nerves of the right upper extremity. Posterior view. |
Important dermatomes and anatomical landmarks
- C6 - (median nerve) 1st digit (thumb)
- C7 - (radial nerve) 2nd and 3rd digit
- C8 - (ulnar nerve) 4th and 5th digit, also the funny bone
- T4 - nipples.
- T5 - Inframammary fold.
- T6 - xiphoid process.
- T10 - umbilicus.
- T12 - pubic bone area.
See also
External links
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
