Variation of Median Nerve Pathway Around the Elbow Joint




Reyes, Aubrie
Wohleb, Evan
Francis, Alex
Liu, Howe


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Introduction The median nerve is one of the large terminal branches originating from the brachial plexus. It provides the motor innervations to both the forearm and palmar hand, as well as most of the sensory innervation for the palmar hand. On the way to its targeted areas, the median nerve pathway from the upper arm to the hand may pass through some muscles and other accessory structures that may not be considered normal, particularly around the elbow area. The purpose of this study was to trace and observe how this nerve travels in terms of the relationship with surrounding structures proximally and distally to the elbow. Methods Twelve upper extremities from six cadavers (3 males and 3 females) were dissected to trace and observe how the median nerve travels in these specimens. The focused area was from the middle upper arm to the proximal 1/3 of the forearm. Results All twelve identified median nerves passed between the biceps brachii and brachialis muscles. In ten out of the twelve specimens, about two to three fingers width proximal to the elbow joint line between the medial and lateral epicondyles of the humerus, it was found that the median nerve surfaced from the inferomedial edge of the biceps muscle and continued traveling down under a tight bicep aponeurosis and then pierced into the pronator teres muscle - common impingement areas for the median nerve. After we reflected the biceps muscle laterally from the remaining two of the twelve left forearms to expose the median nerve, it was observed that the nerve pierced through the brachialis muscle at its superior border (three to four fingers width proximal to the joint line), which was a very interesting finding. The nerve exited from the inferior border of the muscle, continued to pass down for one to two fingers width, and pierced the pronator teres as did the other ten median nerves. Conclusion Observing two of twelve specimens, the median nerve showed a different pathway around the elbow joint, which is abnormal from others’. Namely, the nerve pierces through the brachialis muscle before descending and passing through the pronator teres muscle. Clinical Implication Such a variation of the median nerve pathway has not been reported before. This finding may offer clinicians an additional explanation of the median nerve impingement-related clinical symptoms that are very similar to the pronator teres syndrome.