Dermatomes

Dermatome
Dermatomes of the Upper and Lower Limbs (Modified, after Keegan, J. J., and Garrett, F. D.)
Dermatomes of the Upper Parts of the Body, displaying significant overlapping (Modified, from Fender, after Foerster)
Anatomical terminology []

A dermatome is an area of skin that is mainly supplied by a single spinal nerve. There are 8 cervical nerves (C1 being an exception with no dermatome), 12 thoracic nerves, 5 lumbar nerves and 5 sacral nerves. Each of these nerves relays sensation (including pain) from a particular region of skin to the brain.

A dermatome also refers to the part of an embryonic somite.

Along the thorax and abdomen the dermatomes are 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. Although the general pattern is similar in all people, the precise areas of innervation are as unique to an individual as fingerprints.

A similar area innervated by peripheral nerves is called a peripheral nerve field.

A dermatome is an area of skin supplied by sensory neurons that arise from a spinal nerve ganglion. Symptoms that follow a dermatome (e.g. like pain or a rash) may indicate a pathology that involves the related nerve root. Examples include somatic dysfunction of the spine or viral infection. Referred pain usually involves a specific, "referred" location so is not associated with a dermatome. Certain skin problems tend to orient the lesions in the dermatomal direction.

Viruses that lie dormant in nerve ganglia (e.g. varicella zoster virus, which causes both chickenpox and herpes zoster commonly shingles), often cause either pain, rash or both in a pattern defined by a dermatome (a zosteriform pattern). However, the symptoms may not appear across the entire dermatome.