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

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