Dermatomes are routes that spinal nerves take as they leave the spinal cord and branch out into the body.
The story of dermatomes begins in the spinal column. The spinal column is broken down into levels, as determined by the positions of the vertebrae. For example, the seven cervical vertebrae (in the neck) are called C1-C7, while the five lumbar vertebrae (in the lower back) are called L1-L5. For the most part, these level designations also apply to spinal nerves as they branch off the spinal cord.
From top to bottom, nerve roots branch off the spinal cord and travel through openings in the vertebrae called foramina. There are a total of two nerve roots that branch off at each vertebral level – one on each side of the vertebra. Eventually, the nerve roots branch out further and further, creating a network of nerves throughout the body.
As mentioned previously, the route that nerves travel as they leave the spinal cord and branch out into the body are called dermatomes. Dermatomes can be associated with the body’s sensory nerves (the sense of touch) or the motor nerves (the ability to move). Dermatome routes are significant because the nerves traveling along those routes serve specific areas of the body, which can help doctors isolate and identify which specific nerves are malfunctioning.
Medical professionals have attempted to chart dermatomes throughout the body. Dermatome charts or maps are designed to illustrate bodily areas that are supplied by a single spinal nerve. Often, dermatome maps look like a rainbow-striped human body where each color is associated with a spinal nerve in the cervical (C2-C8), thoracic (T1-T12), lumbar (L1-L5), or sacral (S1-S5) area of the spinal column.
Dermatomes sometimes can be used to isolate problems in the spinal cord because pain on or around a specific dermatome can be traced back to a specific nerve root that is damaged, trapped, or constricted. Dermatome pain mapping also can help to isolate viruses that are infecting the spinal nerves, such as shingles. When dermatome pain, numbness, tingling, or weakness is identified, a physician will most likely palpate the corresponding area of the spine to try and identify the specific damaged nerve root.
The nerves of the spinal cord that control the dermatomes run along the vertebrae as follows:
- Cervical (C-2 through C-7) contain nerves corresponding to the fingers, neck, funny bone, and the scalp.
- Thoracic (T-1 through T-12) contain nerves corresponding to the nipples, chest, belly button area, pubic bone, and lower sternum.
- Lumbar (L-1 through L-5) contain nerves corresponding to the hips, the front of the legs, the shins, knee caps, and most of the feet.
- Sacral (S-1 through S-5) contain nerves corresponding to the genitals, buttocks, back of the legs, and calves
Symptoms within one or more dermatomes will indicate the affected region of the spine. For instance, radiculopathy or radiating leg pain can indicate a problem with the neural roots in the lumbar spine. This could indicate sciatica, which is often caused by a herniated disc pushing against the sciatic nerve. Another possible cause of spinal nerve distress is spinal stenosis caused by degenerative disc disease, a herniated disc, or a bulging disc.
Treatment for these issues generally includes rest, physical therapy, pain medication, or steroidal injections. If these conservative treatments prove ineffective, the award-winning surgeons at the Laser Spine Institute (LSI) can introduce you to state-of-the-art, minimally-invasive, endoscopic procedures that can help you rediscover a life without pain. Contact us today for more information on dermatomes, and for a free review of your MRI or CT scan.