Pronator teres muscle

The pronator teres is a muscle of the human body (located mainly in the forearm) that, along with the pronator quadratus muscle, serves to pronate the forearm (turning it so that the palm faces posteriorly).

Structure

The pronator teres has two heads--humeral and ulnar.

The humeral head, the larger and more superficial, arises from the medial supracondylar ridge immediately superior to the medial epicondyle of the humerus, and from the common flexor tendon (which arises from the medial epicondyle).

The ulnar head is a thin fasciculus, which arises from the medial side of the coronoid process of the ulna, and joins the preceding at an acute angle.

The median nerve enters the forearm between the two heads of the muscle, and is separated from the ulnar artery by the ulnar head.

The muscle passes obliquely across the forearm, and ends in a flat tendon, which is inserted into a rough impression at the middle of the lateral surface of the body of the radius, just below the insertion of the supinator.

The lateral border of the muscle forms the medial boundary of the triangular hollow known as the cubital fossa, which is situated anterior to the elbow.

Innervation

The pronator teres is innervated by the median nerve.

Action

Pronator teres pronates the forearm, turning the hand posteriorly. If the elbow is flexed to a right angle, then pronator teres will turn the hand so that the palm faces inferiorly. It is assisted in this action by pronator quadratus.

It also weakly flexes the...
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