Anterior Root of Seventh Cervical Nerve (Right)

Origin

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

Course

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

Those passing through the anterior ramus convey motor fibers to the middle trunk of the brachial plexus. Fibers that enter the lateral cord of the brachial plexus help innervate muscles of the anterior compartment of the arm (coracobrachialis and lateral part of brachialis), pectoralis major, pronator teres, flexor carpi radialis, palmaris longus, flexor carpi ulnaris, flexor pollicis longus, and pronator quadratus. Fibers that enter the posterior cord provide motor innervation to the subscapularis, teres major, latissimus dorsi, triceps, anconeus, extensor carpi radialis longus, supinator, extensor carpi radialis brevis, extensor digitorum, and extensor digiti minimi, extensor carpi ulnaris, abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, and extensor indicis.

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