Dermatomes Nerve Chart (Map and Locations on Skin)
What are dermatomes, and why are they important to our health?
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A dermatome is the area of the skin of the human anatomy that is mainly supplied by branches of a single spinal sensory nerve root. These spinal sensory nerves enter the nerve root at the spinal cord, and their branches reach to the periphery of the body. The sensory nerves in the periphery of the body are a type of nerve that transmits signals from sensations (for example, pain symptoms, touch, temperature) to the spinal cord from specific areas of our anatomy.
To understand dermatomes, it is important to understand the anatomy of the spine. The spinal column is divided into 31 segments, each with a pair (right and left) of anterior and posterior nerve roots. The types of nerves in the anterior and posterior roots are different. Anterior nerve roots are responsible for motor signals to the body, and posterior nerve roots receive sensory signals like pain or other sensory symptoms. The anterior and posterior nerve roots combine on each side to form the spinal nerves as they exit the vertebral canal (the bones of the spine, or backbone).
The 31 spine segments on each side give rise to 31 spinal nerves, which are composed of 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal spinal nerves. There are specific dermatomes for each of these spinal nerves, except the first cervical spinal nerve. Dermatomes are used to represent the patterns of sensory nerves that cover various parts of the body, including the:
How many dermatomes are there, and where are they located on the body?
There are 30 dermatomes on the body. They are numbered according to the corresponding spinal vertebral level from which they emanate. For example, There are:
7 cervical dermatomes (C2-C8, as C1 nerve has no dermatome) - The "C" stands for cervical, which means having to do with any part of the neck, including the neck on which the head is perched, and the neck of the uterus.
12 thoracic dermatomes (T1-T12) - "T" refers to the thoracic, or to the upper torso area of the body or chest (frontal and dorsal).
5 lumbar dermatomes (L1-L5) that supply sensation from these spinal nerves in the lower limb (leg, foot, hip, etc.) - "L" refers to the five lumbar vertebrae, the disks below them, and the corresponding area of the lower back.
5 sacral dermatomes (S1-5) - "S" refers to the sacral or the sacrum, which are located below L5.
1 coccygeal nerve that originates in the spinal cord and emerges at the level of the tail bone (coccyx).
The C1-C7 nerve roots emerge above their respective vertebrae; the C8 nerve root emerges between the C7 and T1 vertebrae, while the remaining nerve roots emerge below their respective vertebrae.
Dermatome Map of the Human Body
Medically Reviewed by a Doctor on 1/17/2017
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