The spinal cord is divided into five regions: cervical, thoracic, lumbar, sacral, and coccygeal. Together, these regions give rise to 31 pairs of spinal nerves that control movement, sensation, and organ function from your neck down to your pelvic floor. Each region handles a distinct zone of the body, and the cord itself is shorter than most people expect, ending around the first or second lumbar vertebra in adults rather than running the full length of the spine.
The Five Regions at a Glance
The regions are stacked from top to bottom, each contributing a specific number of nerve pairs:
- Cervical (C1–C8): 8 nerve pairs
- Thoracic (T1–T12): 12 nerve pairs
- Lumbar (L1–L5): 5 nerve pairs
- Sacral (S1–S5): 5 nerve pairs
- Coccygeal: 1 nerve pair
Notice that the cervical region has eight nerve pairs despite the neck having only seven vertebrae. That’s because the first cervical nerve exits above the first vertebra, giving this region an “extra” pair compared to its vertebral count. Every other region matches its nerve count to its vertebrae one-to-one.
Cervical Region: Head, Neck, and Arms
The cervical region sits at the top of the spinal cord, running through the neck. Its eight nerve pairs (C1–C8) control head and neck movement, shoulder stability, and everything your arms and hands do. C1 through C3 handle forward, backward, and side-to-side movements of the head and neck. Nerves lower in this region branch out to the shoulders, elbows, wrists, and fingers.
One especially critical nerve grouping in this region controls the diaphragm, the muscle that drives breathing. That’s why injuries high in the cervical cord can compromise a person’s ability to breathe independently.
The cervical region is also physically wider than the rest of the cord. This bulge, called the cervical enlargement, reaches its maximum width around the C6–C7 level. The extra size reflects the large concentration of nerve cells needed to manage the fine motor control of the hands and arms.
Thoracic Region: Trunk and Internal Organs
The thoracic region is the longest section of the spinal cord, spanning the upper and middle back with 12 nerve pairs (T1–T12). These nerves supply the muscles of the chest and abdomen that stabilize your trunk and assist with breathing, coughing, and posture.
Beyond muscle control, the thoracic region plays a major role in regulating internal organs through the sympathetic nervous system. Nerve fibers from the upper thoracic ganglia feed into networks that influence heart rate, blood vessel diameter, and airway size in the lungs. Fibers from the lower thoracic levels form the splanchnic nerves, which reach down into the abdomen to regulate digestive organs. These sympathetic signals do things like constrict blood vessels in the skin and gut, dilate blood vessels supplying the heart and skeletal muscles, trigger sweat gland activity, and relax the airway during physical exertion.
Because the thoracic region covers such a long stretch, the skin zones (dermatomes) it serves wrap in horizontal bands around your trunk. If you’ve ever had shingles along a strip of skin on your torso, that outbreak followed the path of a single thoracic nerve.
Lumbar Region: Lower Back and Legs
The five lumbar nerve pairs (L1–L5) control the muscles of the lower back, hips, and much of the legs. Like the cervical region, the lumbar section has an enlargement, though here the extra size comes mainly from increased thickness rather than width, peaking around the L3–L5 segments. This reflects the heavy neural demand of walking, running, and supporting body weight.
Lumbar nerves combine with sacral nerves to form major nerve pathways to the lower body. The most notable is the sciatic nerve, the largest nerve in the body, which originates from fibers spanning L4 through S3. It powers the muscles of the back of the thigh (the hamstrings), bends the knee, moves the ankle, and controls the muscles of the foot. When a lumbar disc herniates, commonly at L4/L5 or L5/S1, it can compress nearby nerve roots and send shooting pain, numbness, or weakness down the leg along specific skin zones.
Sacral and Coccygeal Regions: Pelvis and Pelvic Floor
The five sacral nerve pairs (S1–S5) and the single coccygeal pair handle the pelvic organs, the pelvic floor muscles, and remaining lower limb functions. Sacral nerves contribute to hip movement through the gluteal nerves, with the superior gluteal nerve drawing from L4–S1 and the inferior gluteal nerve from L5–S2.
The sacral region also controls bladder and bowel function. Parasympathetic nerve fibers from S2 through S4 signal the bladder to contract during urination while relaxing the internal sphincter. These same segments govern sexual function and sensation in the genitals, anus, and the skin between them (the perineum). Losing function in this region affects daily independence in ways that go well beyond mobility, which is one reason sacral injuries are taken so seriously even though they don’t affect the arms or legs as dramatically as cervical injuries.
Where the Spinal Cord Actually Ends
The spinal cord does not extend all the way down the spinal column. In adults, it tapers to a point called the conus medullaris, which typically sits at the lower third of the L1 vertebra. The normal range is anywhere from the mid-T12 level to the upper third of L3, and the cord reaches this adult position by birth or within the first two months of life.
Below the conus, the spinal canal isn’t empty. A bundle of long nerve roots called the cauda equina (Latin for “horse’s tail”) fans out from the end of the cord and continues downward through the lower spinal canal, bathed in cerebrospinal fluid. These nerve roots exit at their respective vertebral levels to reach targets supplied by the L2 through S5 spinal cord segments. They carry motor signals to the legs and sensory information like pain, temperature, touch, and proprioception (your sense of where your limbs are in space) back up to the cord and brain.
This anatomy matters in a practical sense: procedures like lumbar punctures and epidural injections are performed in the lower lumbar spine precisely because the cord has already ended there, reducing the risk of direct cord injury while still accessing the fluid and nerve roots below.
How Region of Injury Affects the Body
Because each region controls specific body zones, the level of a spinal cord injury determines what functions are lost. Damage to the cervical cord can cause paralysis in all four limbs (quadriplegia), since every signal to the arms, trunk, and legs must pass through that section. An injury lower in the cord, in the thoracic or lumbar region, typically affects only the lower body (paraplegia), leaving arm and hand function intact.
Each spinal nerve also maps to a specific strip of skin, called a dermatome. If you lose sensation in a particular band of skin, or lose muscle control in a specific area, that pattern tells clinicians exactly which nerve root or spinal cord level is involved. A weakened ankle reflex, for example, points to the S1 nerve root. Numbness wrapping around one side of the ribcage suggests a thoracic nerve issue. This dermatome map is essentially a diagnostic guide written into the body’s wiring, linking every patch of skin and every muscle group back to a precise level of the spinal cord.