Lateral Root of Median Nerve (Left)

Origin

The lateral root of median nerve comes off as a terminal branch of the lateral cord of brachial plexus (C5, C6, C7). The other terminal branch being the musculocutaneous nerve.

Course

The median nerve has two roots; the lateral root and the medial root. The lateral root comes off from the lateral cord (C5-C7) while the medial root comes off from the medial cord (C8, T1) of brachial plexus. Both roots embrace the third part of axillary artery. The median nerve is formed by the union of both lateral and medial roots, either anterior or lateral to the axillary artery.

Branches

There are no named branches and directly contributes to the median nerve.

Supplied Structures

The median nerve is a mixed nerve which contains sensory and motor neuronal fibers from the C5—C7 cervical segments of the spinal cord. It provides motor innervation to the muscles of the anterior compartment of the forearm and the hand musculature. The lateral root nerve fibers are predominantly directed towards the forearm musculature, whereas the medial root fibers are predominantly reserved for the hand musculature.

Some fibers from C7 leave the lateral root in the lower part of the axilla and pass distomedially posterior to the medial root, and usually anterior to the axillary artery, to join the ulnar nerve. They are sometimes also referred to as the lateral root of ulnar nerve. Clinically they are believed to be mainly motor and to supply flexor carpi ulnaris (Drake, Vogl and Mitchell, 2014).

Note that if the lateral root is small, the musculocutaneous nerve (C5, 6, 7) connects with the median nerve in the arm (Drake, Vogl and Mitchell, 2014).

References

Drake, R., Vogl, A. W. and Mitchell, A. W. M. (2014) Gray's Anatomy for Students E-Book. Gray's Anatomy: Elsevier Health Sciences.