Anterior Root of Second Cervical Nerve (Right)

Origin

The anterior root of the second cervical nerve forms from a series of rootlets that emerge from the anterolateral sulcus of the second cervical spinal segment.

Course

The anterior root of the second cervical nerve runs laterally and inferiorly away from the second cervical spinal segment towards the intervertebral foramen located between the atlas (C1 vertebra) above and the axis (C2 vertebra) below. Roughly within this intervertebral foramen, the anterior root merges with the posterior root to form the second cervical nerve.

Size and direction of the spinal roots vary. For instance, the upper cervical roots are short and run horizontally to exit the vertebral canal through the foramen.

Branches

The anterior root of the second cervical nerve merges with the posterior root to form the second cervical nerve and does so without branching.

Supplied Structures

The somatic motor efferents pass through the spinal nerve itself and into either the posterior ramus or the anterior ramus of the first cervical nerve.

Those passing through the anterior ramus contribute to the cervical plexus. It innervates the infrahyoid muscles (sternohyoid, sternothyroid and inferior belly of omohyoid) via the ansa cervicalis. Other muscles innervated include the anterior prevertebral muscles, including rectus capitis anterior and lateralis and longus colli muscles.

Fibers that pass through the posterior ramus innervate the obliquus capitis inferior muscle via communications sent from the greater occipital nerve to the suboccipital nerve. Fibers which pass through the smaller lateral branch of the posterior ramus innervate the longissimus capitis, semispinalis capitis, and splenius capitis muscles.