Anterior Root of Fourth Cervical Nerve (Left)

Origin

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

Course

The anterior root of the fourth cervical nerve runs laterally and inferiorly away from the fourth cervical spinal segment towards the intervertebral foramen located between the third and fourth cervical vertebrae. Roughly within this intervertebral foramen, the anterior root merges with the posterior root to form the fourth 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 fourth cervical nerve merges with the posterior root to form the fourth 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 fourth cervical nerve.

Those passing through the anterior ramus contribute to the cervical plexus. It innervates the longus colli and anterior and middle scalene muscles.

Fibers that pass through the posterior ramus innervate the longissimus colli, splenius colli, iliocostalis colli, multifidus, semispinalis colli, semispinalis colli, and trapezius muscles.