Brachialis arises from the anterior surface of the shaft of the humerus, below the insertion of deltoid. It inserts into the coranoid process of the ulna.
It flexes the elbow joint in both the prone and supine position and can be tested by palpating the fibres during resisted flexion.
It is supplied by the musculocutaneous nerve which, after piercing coracobrachialis, lies between biceps and brachialis.