Three Unique Variations of the Neurovascular Course of the Profunda Brachii Artery

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Abstract Body : Introduction
Neurovascular distribution in the upper extremity is subject to variability and is more common than anticipated. Classically, the brachial plexus is a network of nerves involving the anterior rami of C5-T1, trunks, divisions, and cords. The lateral cord provides the musculocutaneous nerve and lateral root of the median nerve, the medial cord provides the ulnar nerve and medial root of the median nerve, and the posterior cord provides the axillary and radial nerves.
Variations of the plexus are often reported in association with vascular anomalies. Upper limb vasculature classically involves the axillary artery, which begins at the first rib and is characterized in relation to the pectoralis minor muscle. As it continues into the arm past the inferior border of teres major, it becomes the brachial artery.
Herein, we present a unique combination of three anatomical anomalies that are not well-documented in the current literature to the best of the authors knowledge. Most notably, the profunda brachii artery branched from the subscapular artery.

Methods
During routine dissection of the right upper extremity of a cadaver, we observed an additional contribution from the lateral cord to the median nerve that communicated with its medial root prior to forming the median nerve. Additionally, the ipsilateral brachial artery was entirely anterior to the median nerve and emerged anteriorly to where the communicating branch of the lateral cord joined the medial root of the median nerve. Furthermore, the subscapular, rather than the brachial, artery provided the profunda brachii artery.

Discussion
Median nerve variations are commonly reported in the literature. Examples from previous literature include a proximal and distal lateral root of the median nerve, formation of the median nerve from a single root of the lateral cord, and the complete absence of the lateral root of the median nerve. Other reports have documented the median nerve receiving contribution from two branches of the lateral cord and one branch of the medial cord.
Many variations in upper extremity vasculature have been reported given the complexity of development of the arterial supply of the upper limb during embryogenesis. For example, the axillary artery has been observed to be anteromedial to the plexus at the point of merge between the lateral and medial cords, and even giving rise to superficial brachial and superficial subscapular arteries in the absence of a normal brachial artery. In another variation, the axillary artery bifurcated into large superficial and deep brachial arteries after passing between the medial and lateral cords.
The profunda brachii artery, the largest branch of the brachial artery, has been documented to have many variations in origin. The most prevalent variant is the anomalous origin from the axillary artery rather than the brachial artery. Alternative origins are as a common trunk with the superior ulnar collateral artery or as a branch of the circumflex humeral artery. However, this is the first documented finding listing the origin of the profunda brachii artery as the subscapular artery.

Clinical Significance
Variations involving roots of the median nerve, a superficial brachial artery, and an abnormal origin of the profunda brachii artery from the subscapular artery were observed. It is important for clinicians to be aware of such variations for proper diagnosis and treatment of injuries associated with the upper extremity.