Anterior Root of Fifth Cervical Nerve

Origin

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

Course

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

Those passing through the anterior ramus convey motor fibers to the superior trunk of the brachial plexus. Fibers that enter the lateral cord of the brachial plexus help innervate muscles of the anterior compartment of arms (biceps brachii, coracobrachialis, brachialis), pectoralis major, various muscles of the anterior forearm and some intrinsic hand muscles. Fibers that enter the posterior cord provide motor innervation to the subscapularis and teres major, latissimus dorsi, deltoid, teres minor, and brachioradialis.

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