What is a Dermatome Map?
A Dermatome Map is a clinical guide that shows the dermatome areas. A dermatome is an area of skin supplied by a single spinal nerve, each connected to a dorsal root ganglion. Traumatic injury to a nerve root can lead to symptoms affecting the entire body through its corresponding dermatome. From the spinal cord, 31 pairs of spinal nerves branch out as roots to the skin like a network, also known as peripheral nerves. These areas have two-way functions; they deliver and receive sensational signals to the brain.
The 31 pairs of spinal nerves are spread out in your body based on the region of the spinal nerve roots they are connected to. These human dermatomes are divided into five groups:
- Cervical nerves: These nerves originate from the upper neck and are numbered C1 through C8 in pairs.
- Thoracic nerves: These spinal nerves exit the spine into the torso. They are numbered T1 through T12 in pairs.
- Lumbar nerves: These nerves originate from the spine up to the lower back and are numbered L1 through L5 in pairs.
- Sacral nerves: These are like the lumbar nerves; they are connected with the sacrum, one of the bones found in the pelvis, and numbered S1 through S5 in pairs.
- Coccygeal nerves: This pair of nerves are located at the buttocks or from the coccyx or tailbone area.
In addition, there are also dermatomes on the face, which are primarily innervated by the trigeminal nerve (cranial nerve V), not by the spinal nerves. This nerve has three branches:
- Ophthalmic (CN V1): Innervates the forehead and nose.
- Maxillary (CN V2): Supplies the skin over the cheekbones and upper jaw.
- Mandibular (CN V3): Covers the skin over the lower jaw and areas in front of the ear.
The nerve map follows a different pattern depending on the region where the spinal nerve is located. The locations of the dermatome reveal essential information that would help diagnose the patient's condition.










