wiki-A dermatome is an area of skin that is mainly supplied by a single spinal nerve. There are eight cervical nerves, twelve thoracic nerves, five lumbar nerves and five sacral nerves. Each of these nerves relays sensation (including pain) from a particular region of skin to the brain. My understanding is that one spinal nerve contains bothe afferent and efferent fibers. So shouldn't a dermatome have an efferent compartment as well. Do dermatomes only have afferent fibres or is it simply that we consider only the afferent part as the dermatome of that spinal nerve. Thanks!!