Muscular branches of cervical plexus

The muscular branches of cervical plexus refer to its deep motor branches that primarily supply motor innervation to various neck muscles and the diaphragm. These include:

Motor branches to neck muscles

1. Direct branches to prevertebral muscles

• Innervate the rectus capitis anterior, rectus capitis lateralis, longus capitis, and longus colli muscles, which are anterior to the cervical vertebral column.

2. To sternocleidomastoid and trapezius (C2–C4)

• Some fibers contribute to the accessory nerve (cranial nerve XI) for innervating the sternocleidomastoid and trapezius muscles.

3. To geniohyoid and thyrohyoid muscles (C1)

• The cervical plexus also gives a communicating branch from C1 spinal nerve to the hypoglossal nerve which almost immediately leaves to supply the geniohyoid and thyrohyoid muscles.

4. To diaphragm via phrenic Nerve (C3–C5, predominantly C4)

• The phrenic nerve is a prominent branch of the cervical plexus. It travels inferiorly, running on the scalenus anterior, and supplies motor innervation to the diaphragm. It also carries sensory fibers to parts of the pericardium, mediastinal pleura, and the diaphragm's central tendon.

Motor branches via the ansa cervicalis

The ansa cervicalis is a loop of nerves derived mostly from C1 to C3, which provides motor innervation to the infrahyoid muscles (except the thyrohyoid). For details click here.