Abstract
The brachial plexus innervates the upper extremities. While variations in the formation of the brachial plexus and its terminal branches are quite common, it is uncommon for the median nerve to innervate the muscles of the arm. During the dissection of an elderly male cadaver at the Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India, in 2016, the coracobrachialis muscle was found to be supplied by a direct branch from the lateral root of the median nerve and the musculocutaneous nerve was absent. The branches of the median nerve supplied the biceps brachii and brachialis muscles and the last branch continued as the lateral cutaneous nerve of the forearm. These variations may present atypically in cases of arm flexor paralysis or sensory loss on the lateral forearm. Knowledge of these variations is important in surgeries and during the administration of regional anaesthesia near the shoulder joint and upper arm.
Highlights
The brachial plexus innervates the upper extremities
During the dissection of an elderly male cadaver at the Department of Anatomy, All India Institute of Medical Sciences, New Delhi, India, in 2016, the coracobrachialis muscle was found to be supplied by a direct branch from the lateral root of the median nerve and the musculocutaneous nerve was absent
An upper limb dissection of an elderly male cadaver was performed during a routine educational dissection at the Department of Anatomy of the All India Institute of Medical Sciences, New Delhi, India, in 2016
Summary
The left lateral cord gave rise to a lateral pectoral nerve and, distal to this branch, it continued as the lateral root of the median nerve around the third part of the axillary artery. A branch originated from the lateral root of the median nerve and supplied the coracobrachialis muscle. The median nerve was formed by the union of the medial and lateral roots from the respective medial and lateral cords of the brachial plexus, anterior to the axillary artery. The branches from the median nerve supplied the flexor muscles of the left arm, except the coracobrachialis muscle, and the last branch continued as the lateral cutaneous nerve of the forearm. The medial to lateral side, piercing the deep fascia and continuing as the lateral cutaneous nerve of the forearm, superficial to the brachioradialis muscle [Figure 1]. No other variations were found in relation to the other vessels and muscles
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