Pronator teres

Pronator teres muscle
Anterior view of the left forearm. Superficial muscles. (Pronator teres colored at center.)
Details
Origin	humeral head: medial supracondylar ridge of humerus (common flexor tendon) ulnar head: coronoid process of ulna
Insertion	Middle of the lateral surface of the body of the radius
Artery	ulnar artery and radial artery
Nerve	median nerve
Actions	pronation of forearm, flexes elbow
Antagonist	Supinator muscle
Identifiers
Latin	Musculus pronator teres
TA	A04.6.02.025
FMA	38450
Anatomical terms of muscle []

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

The pronator teres has two heads—humeral and ulnar.

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 distal to 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.

The pronator teres is innervated by the median nerve.

To stimulate the pronator teres, a signal begins in the precentral gyrus in the brain and goes down through the internal capsule. It continues down the corticospinal tracts through the capsule, midbrain, and pons where it arrives at the medullar pyramids. Once at the pyramids, the corticospinal tracts decussate and the signal goes down the lateral corticospinal tract until it reaches the ventral horns of C5, C6, C7, C8, and T1. The signal then goes through the ventral rami and down the root ganglion of C5, C6, C7, C8, and T1 (Brachial Plexus). Next, the signal goes down the median nerve branch of the Brachial Plexus and stimulates the Pronator Teres to contract causing the hand to pronate.

Occasionally, the ulnar head is absent. Also, additional slips from the medial intermuscular septum, from the biceps brachii, and from the brachialis occasionally occur.