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Spinal Nerves

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Spinal Nerves

The nervous system is divided into two systems. The Central Nervous System which is the brain and the spinal cord, and the Peripheral Nervous System which is the 12 cranial nerves, 31 pairs of spinal nerves and ganglia. The Peripheral Nervous System provides communication between the brain and spinal cord and the body’s muscles, glands and sensory receptors.

The spinal cord is the continuation of the brainstem, it lies protected within the vertebral column of the spine. A spinal nerve is any of the 31 pairs of nerves that arise from the spinal cord. The spinal nerves are named according to where it emerges and passes through the bones in the spinal vertebrae. As you can see in the image to the left, the nerve roots (in red) come off the spinal cord and out to the rest of the body between the vertebra. Most of the spinal nerves exit at the vertebrae that protects it, however, the C1 nerve exits above the C1 vertebra and the sacral and coccygeal nerves exit at these bones.

The 31 pairs of spinal nerves are:

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Each spinal nerve is attached to the spinal cord by two roots: a dorsal (back, posterior) sensory root and a ventral (front, anterior) motor root . The fibers of the sensory root carry sensory impulses to the spinal cord—pain, temperature, touch and position sense (proprioception)—from tendons, joints and body surfaces. The motor roots carry impulses from the spinal cord.The nerves carry messages to and from the skin of specific body regions called dermatomes.

Dermatome Map of Upper Limb (Shoulder, Arm, and Hand)

Dermatomes of the right shoulder, arm and hand.
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To help you better understand the medical terms used here and other anatomy of the spine refer to these pages on our site:

Nerve Plexus

The spinal nerves exit the spinal cord and pass through the intervertebral foramen, then divides into four branches, or networks, called plexuses.

Relation of Spinal Nerves to Vertebrae

Relation of Spinal Nerves to Vertebrae

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