Median nerve and brachial artery entrapment in the abnormal brachialis muscle – a case report

Brachialis muscle lies beneath the biceps brachii and arises from anteromedial and anterolateral surfaces of the lower half of the shaft of humerus. A few fibers take origin from lower part of spiral groove and medial intermuscular septum also. The broad muscle covers the anterior part of elbow joint and converges to form a flat tendon which is inserted into the anterior surface of coronoid process and tuberosity of ulna. The major part is supplied by musculocutaneous nerve and the small lateral part by radial nerve. Brachialis flexes the elbow joint. The brachial artery begins as a continuation of the axillary artery and is superficial throughout its course in the arm. When it enters the cubital fossa it lies anterior to brachialis and lateral to median nerve. At the cubital fossa it is crossed by the bicipital aponeurosis which separates the artery from the median cubital vein. The median nerve descends along the lateral side of the third part of axillary artery and proximal part of brachial artery. At the middle of the arm opposite the insertion of coracobrachialis the nerve crosses from lateral to medial, usually in front of the artery and then accompanies along the medial side of the brachial artery. It appears in the cubital fossa beneath the bicipital aponeurosis and rests on the brachialis. The nerve leaves the cubital fossa through a gap between the superficial and deep heads of pronator teres. We saw variation of insertion of brachialis and course of median nerve and brachial artery in the right upper limb.