Dermatome
A Dermatome is an area of skin supplied by sensory nerve fibers from a single spinal nerve root. There are 30 defined dermatomes in the body—divided into cervical, thoracic, lumbar, sacral, and coccygeal sections—that form a neurological map of your body.
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.
An area of skin innervated by a single nerve is called a peripheral nerve field. The word dermatome is formed from Ancient Greek δέρμα 'skin, hide' and τέμνω 'cut'.
The 4 Main Dermatome Sections
The nervous system is highly organized, with each spinal nerve serving a specific region:
- Cervical (C1-C8): Innervate the neck, shoulders, and arms.
- Thoracic (T1-T12): Innervate the chest, abdomen, and middle of the back.
- Lumbar (L1-L5): Innervate the front of the legs, knees, and upper/outer parts of the feet.
- Sacral (S1-S5): Innervate the groin, genitals, buttocks, and the back of the legs.[2]
Clinical significance
Referred Pain: Conscious perception of visceral sensations is referred to specific regions of the body that are not sources of the sensations. Some referred pain due to visceral sensations refer to dermatomes that send fibers to the same level of the spinal cord.
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., pain or a rash) may indicate a pathology that involves the related nerve root. Examples include somatic dysfunction of the spine or viral infection. Certain skin problems tend to orient lesions along dermatomal lines.
In Referred Pain, sensory nerve fibers such as those from dermatomes may come together at the same spinal cord level as the general visceral afferent fibers such as those from the heart. When the general visceral sensory fiber is stimulated, the central nervous system does not clearly discern whether the pain is coming from the body wall or from the viscera, so it perceives the pain as coming from somewhere on the body wall, e.g., left arm/hand pain, jaw pain. So the pain is "referred to" the related dermatomes of the same spinal segment.[3]
Viruses that lie dormant in nerve ganglia (e.g., varicella zoster virus, which causes both chickenpox and 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.
