Anterior rami of cervical nerves

The anterior rami of cervical nerves (C1-C8) are the larger branches of the cervical nerves that emerge from the spinal cord. These rami play a vital role in providing motor and sensory innervation to the neck, shoulders, upper chest, and upper limbs.

Except for the first cervical nerve, the anterior rami of cervical nerves pass outward between the Intertransversarii anterior and posterior muscles, running along the grooved upper surfaces of the transverse processes of the cervical vertebrae.

The anterior division of the first cervical nerve, exits the vertebral canal above the posterior arch of the atlas. It courses forward, curving around the lateral aspect of the superior articular process of the atlas and lying medial to the vertebral artery. Typically, the suboccipital nerve descends medial to and anterior to the Rectus capitis lateralis muscle. It is important to note that the anterior division of the C1 nerve is purely motor and lacks sensory fibers.

The anterior rami of the upper four cervical nerves (C1-C4) form the cervical plexus, which primarily innervates the muscles and skin of the neck and shoulders. One of the key branches of the cervical plexus is the phrenic nerve, which arises primarily from C3-C5 and supplies motor innervation to the diaphragm, a muscle critical for respiration.

Details for structures innervated by anterior rami of upper four cervical nerves can be found here:

• Spinal nerve C1

• Spinal nerve C2

• Spinal nerve C3

• Spinal nerve C4

In contrast, the anterior rami of the lower cervical nerves (C5-T1) contribute to the formation of the brachial plexus, a complex network of nerves responsible for the motor and sensory innervation of the upper limb. The brachial plexus provides motor supply to major muscle groups and sensory supply to the skin of the shoulder, arm, forearm, and hand.

Details for structures innervated by anterior rami of lower four cervical nerves can be found here:

• Spinal nerve C5

• Spinal nerve C6

• Spinal nerve C7

• Spinal nerve C8