There are 31 pairs of spinal nerves, giving you a total of 62 individual nerves branching out from your spinal cord. These 31 pairs are grouped into five regions based on where they exit the spine: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal.
How the 31 Pairs Break Down by Region
Each pair of spinal nerves exits from a specific segment of the spinal cord, with one nerve going to the left side of your body and one to the right. The five regions correspond to the sections of your vertebral column, though the match isn’t always one-to-one.
- Cervical (C1 through C8): 8 pairs. These serve your head, neck, shoulders, arms, and hands.
- Thoracic (T1 through T12): 12 pairs. These serve your upper back, chest, and abdomen.
- Lumbar (L1 through L5): 5 pairs. These serve your lower back, hips, and front of your legs.
- Sacral (S1 through S5): 5 pairs. These serve the backs of your legs, feet, and pelvic organs.
- Coccygeal (Co1): 1 pair. This small nerve serves the skin around your tailbone.
Why There Are 8 Cervical Nerves but Only 7 Vertebrae
This is the detail that trips most people up. You have seven cervical vertebrae in your neck, yet eight cervical nerve pairs. The reason is that the first cervical nerve (C1) exits above the first vertebra, between the skull and the top of the spine. Each subsequent cervical nerve also exits above its numbered vertebra. That pattern creates an “extra” nerve: C8 exits below the seventh cervical vertebra. From the thoracic region downward, each nerve exits below its corresponding vertebra, and the numbers line up neatly again.
What Each Spinal Nerve Actually Does
Every spinal nerve is a “mixed” nerve, meaning it carries two types of signals. One root entering the spinal cord brings sensory information (touch, pain, temperature) from a specific strip of skin called a dermatome. The other root carries motor signals from the spinal cord out to muscles, telling them when and how hard to contract.
Dermatomes map the body in a surprisingly orderly pattern. The C2 and C3 nerves supply the upper neck and the back of the head. C4 and C5 cover the shoulders and upper arms. C6 and C7 extend down to the forearm, thumb, and index and middle fingers. The thoracic nerves wrap around the trunk in horizontal bands, while the lumbar and sacral nerves cover the legs and feet. Some people lack a C1 nerve entirely, which is a normal anatomical variation.
How Spinal Nerves Form Larger Networks
Spinal nerves don’t simply travel solo to their final destination. In several regions, they weave together into networks called plexuses, where fibers from multiple spinal levels combine and redistribute. This is why a single injury can cause symptoms that seem to affect unrelated body parts.
The brachial plexus, formed by nerves C5 through T1, gives rise to every major nerve in your arm, including the ones that control grip strength and finger sensation. The lumbar plexus draws from T12 through L4 and supplies the front of your thigh and inner leg. The sacral plexus, built from L4 through S4, produces the sciatic nerve, the largest nerve in the body, which runs from your lower back down the back of each leg.
What Happens When a Spinal Nerve Gets Compressed
When a spinal nerve root is pinched or compressed, typically by a herniated disc or a bone spur, the result is a condition called radiculopathy. Symptoms depend on which nerve is affected but commonly include sharp pain that radiates into the arms or legs, numbness or tingling (“pins and needles”), and weakness in specific muscles. Even coughing or sneezing can intensify the pain because these actions briefly increase pressure inside the spinal canal.
The lower back is the most common site for nerve compression, largely because the lumbar spine bears the most mechanical load. The cervical spine is the second most common. Thoracic radiculopathy, affecting the mid-back, is the least common because the rib cage limits movement and reduces wear on those discs. Knowing which of the 31 nerve pairs is involved helps pinpoint the exact location of the problem, since each nerve maps to a predictable strip of skin and set of muscles.