Pronator teres muscle

Pronator teres muscle
Anterior view of the left forearm. Superficial muscles. (Pronator teres colored at center.)
Latin	musculus pronator teres
Gray's	subject #125 446
Origin	humeral head: medial epicondyle of humerus (common flexor tendon) ulnar head: coronoid process of ulna
Insertion	radius
Artery	ulnar artery and radial artery
Nerve	median nerve
Actions	pronation of forearm, flexes elbow
Antagonist	Supinator 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 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 elbow, or assists in flexion at the elbow when there is strong resistance.

Variations

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

Clinical aspects

Pronator teres syndrome is one cause of wrist pain. It is a type of neurogenic pain.

• patients with the pronator teres syndrome have numbness in median nerve distribution w/repetitive pronation/supination of the forearm, not flexion and extension of the elbow;
• early fatigue of the forearm muscles is seen with repetitive stressful motion, especially pronation;
• EMG may show only mildly reduced conduction velocities;
• despite their anatomic proximity, pts w/ pronator teres syndrome do not have a higher incidence of AIN syndrome;
• other sites of compression:
  • ligament of Struthers
  • lacertus fibrosis
  • pronator teres muscle,
  • proximal arch of the FDS
  • rare causes such as following tendon transfers for radial palsy;
• dissimilarity to CTS
  • positive Tinel's in forearm rather than at wrist
  • negative phalen's test
  • dysesthesia of palmar triangle
  • pain on resistance to pronation
  • pain in forearm on resistance to isolated flexion of the PIP joint of long and ring fingers;

See also

• Pronator quadratus
• Supinator
• Cubital fossa

Additional images

Left humerus. Anterior view.	Bones of left forearm. Anterior aspect.	Cross-section through the middle of the forearm.	The brachial artery.
The radial and ulnar arteries.

External links

• LUC prt
• UWASH pronatorteres
• -234487749 at GPnotebook
• Duke Orthopedics pronator_teres
• PTCentral
• http://www.wheelessonline.com/ortho/pronator_teres

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.

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