The pronator teres is a thick and strong muscle which lies on the anterior side of proximal portion of forearm. It arises by two heads; the humeral head, which is the larger, originates from the medial epicondyle of humerus, the medial intermuscular septum, and the anterior brachial fascia. The ulnar head, on the other hand, arises from the medial edge of the tuberosity of ulna.
The two heads of the pronator teres muscle join together to form a thick muscular belly, which travels down obliquely and laterally as it stretches superficially over the head of the flexor carpi radialis muscle. It finally ends in a narrow tendon which is inserted into the middle third of the lateral surface of radius.
Action
The pronator teres has two functions; it pronates the forearm (it twists it inwardly), and it also helps and assists the biceps brachii in the flexion of forearm at the elbow-joint.
Innervation
This muscle is innervated by the median nerve (C6-C7).
Blood Supply
The pronator teres is supplied by branches of the brachial, ulnar, and radial artery.
Below, anterior view of right forearm, showing the three muscles that pronate and supinate it.
Anterior aspect of right forearm, showing the pronator teres extending superficially over the proximal portion of the flexor carpi radialis muscle.
