Pronator teres muscle (anatomy)

Pronator teres is an arm muscle which has two functions:

• pronation of the forearm; assists pronator quadratus
• flexes forearm at elbow joint

It originates from two sites:

• humeral head: common flexor tendon from medial epicondyle and the distal part of the medial supracondylar ridge
• ulnar head: medial surface of coronoid process of ulna; the ulnar artery passes deep to this attachment

The median nerve passes between the two heads before they fuse. The muscle then passes obliquely across the arm to attach to the lateral surface of the radius near its point of maximum convexity.

It is innervated by the first branch of the median nerve (C6, C7) which usually arises in the forearm but infrequently arises in the arm.

Pronator teres forms the medial boundary of the cubital fossa and it is at this site that the muscle is palpated when it is tested by pronation against resistance.