
Dermatomes
'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
Important dermatones 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.
★ T7 -
xiphoid process.
★ T10 -
umbilicus.
★ L1 -
pubic bone area.
See also
★
Cutaneous innervation
★
Myotome
External links
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