A dermatome is the area of cutaneous distribution of a single spinal nerve; there is considerable overlap between adjacent dermatomes.

The seventh thoracic spinal nerves supply a band of skin around the thorax and anterior abdominal wall over the seventh intercostal spaces posteriorly extending to the middle of the sixth intercostal spaces above and the eighth intercostal spaces below, to the upper half of the region between the xiphisternal joint and umbilicus anteriorly.