Median nerve and medial cords of the brachial plexus, courses through the anterior part of arm, forearm, and hand, and terminates by supplying the muscles of the hand. After receiving inputs from both the lateral and medial cords of the brachial plexus, the median nerve enters the arm from the axilla at the inferior margin of the teres major muscle. It then passes vertically down and courses lateral to the brachial artery between biceps brachii (above) and brachialis (below). At first, it is lateral to the artery and lies anterior to the elbow joint; it then crosses anteriorly to run medial to
Perforating branches of internal thoracic artery Perforating branches of internal thoracic artery The perforating branches of the internal thoracic artery pierce through the internal intercostal muscles of the superior six intercostal spaces. These small arteries run with the anterior cutaneous branches of the intercostal nerves. The perforating arteries constitute part of the blood supply to the pectoralis major and the overlying tissue and skin. The second, third and fourth perforating branches give off medial mammary branches, which become enlarged during lactation. Chung, Kyung Wong, Ph.D. "Board Review Series: Gross Anatomy, 3rd ed. 114-115. Williams and Wilkins: 1995." Lockhart, R.D., et al. "Anatomy of the Human Body."