Dermatome

The dermatome (from Greek derma = skin and tome = cut) is the segmental (stripe-shaped) skin area sensitively innervated by a spinal nerve.

During the segmentation of the embryo, first the primordial vertebrae (somite) develop in the trunk region from the paraxial mesoderm, laterally from the neural tube and the chorda dorsalis. From their dorsolateral part the skin is formed. This anlage is called dermatome. This segmental origin of the individual skin areas results in a segmental assignment to the corresponding spinal nerve. This segmental assignment of the spinal nerves to corresponding skin areas is also preserved in the adult.

Since viscerosensitive sensations are also transmitted via spinal nerves, but these cannot be precisely assigned in the cerebral cortex, these visceral pain impulses are (erroneously) assigned to corresponding sensitive skin areas, usually to that of the same spinal nerve. In the case of diseases of internal organs, hyperaesthesia to external stimuli can thus develop in a certain dermatome(Head's zone).