What is Dermatome?
A dermatome is the band of skin supplied by a single nerve fiber from a spinal nerve.
There are eight cervical (neck) nerves (C1 being an exception with no dermatome), twelve thoracic (chest) nerves, five lumbar (back) nerves and five sacral (hip) nerves.
The dermatomes, as depicted in the illustration, are labeled with a letter and number to represent the area of body each serves. For example, T1 refers to the first thoracic nerve. This illustration is representative of the shingles dermatomal pattern.
Each nerve sends sensations such as pain from that area of skin to the brain. The body is split into two halves. This is because each nerve runs from one side of the spine in the back to the middle of the front of the body and does not cross this midline. This is important when considering the rash of shingles. The rash will occur in a dermatome and will not cross the midline of the body either in the front or the back.
As you will find out, understanding this concept will help you better mange your after shingles pain referred to as postherpetic neuralgia or phn for short.
This video briefly describes the anatomy of dermatomes.