Cervical nerves

The cervical nerves are composed of eight pairs of spinal nerves (C1–C8) originating from the cervical region of the spinal cord. These nerves are classified as mixed nerves, containing both motor and sensory components, except the first cervical nerve (C1), which lacks a sensory component. Each cervical spinal nerve exits the vertebral column via the intervertebral foramina. Notably, the first cervical nerve (C1), a.k.a. suboccipital nerve, emerges between the skull and the atlas (the first cervical vertebra). In contrast, the remaining cervical nerves exit above their corresponding vertebrae, except for the eighth cervical nerve (C8), which exits below the seventh cervical vertebra.

After exiting the spinal cord, each cervical spinal nerve bifurcates into two primary branches: the anterior (ventral) rami and the posterior (dorsal) rami. The anterior rami are typically larger and contribute to the formation of major nerve plexuses. For example, the cervical plexus (C1–C4) and the brachial plexus (C5–C8) arise from these rami, innervating structures in the neck, shoulder, upper chest, and upper limb. In contrast, the posterior rami are smaller and primarily supply the muscles and skin of the posterior neck and upper back regions.

The cervical nerves C3, C4, and C5 also play a vital role in forming the phrenic nerve, which innervates the diaphragm. This nerve is critical for respiration, as it facilitates the contraction and relaxation of the diaphragm, the primary muscle involved in breathing.