Pronator Teres

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Top Contributors - Peter Zatezalo, Ilona Malkauskaite, Joao Costa, Evan Thomas, Kirenga Bamurange Liliane and Ewa JaraczewskaPeter Zatezalo, DPT

Description

The pronator teres muscle is a long, round muscle that is located on the anterior aspect of the forearm. This muscle has two different points of origin: the humeral head and the ulnar head.  The humeral head is larger and more superficial. The ulnar head is deeper and joins it at an acute angle, forming one muscle belly. The ulnar head is sometimes more tendinous, sometimes more muscular, and at times is absent.

The median nerve commonly passes between the two heads of the pronator teres (83% of arms) where it is at risk for compression. The pronator teres forms the medial border of the Cubital Fossa, as illustrated in the image.

Image: Pronator teres muscle (highlighted in green) - posterior view

Origin

Origin of Humeral Head: Immediately above the medial epicondyle of the humerus, common flexor tendon and deep antebrachial fascia.

Origin of Ulnar Head: Medial side of the coronoid process of the ulna.

Insertion

Middle of the lateral surface of the radius.

Nerve

Median nerve, C6 and C7.

Artery

Ulnar artery, anterior recurrent ulnar artery.

Function

Pronator teres pronates the forearm and assists in flexion of the elbow joint.It acts synergistically with the pronator quadratus. If the elbow is fully flexed, then the muscle fibers are shortened and less able to produce force.

Synergist: Pronator Quadratus

Antagonist: Supinator, Biceps Brachii

Clinical relevance

Nerve Entrapment

Path of the median nerve through pronator teres

The median nerve typically runs between the two heads of the pronator teres, making it a possible site of nerve entrapment. There will likely be pain and paresthesia in the distribution of the median nerve.

This entrapment can present similarly to carpal tunnel because the median nerve is affected. If pronator syndrome is present, the individual should have a negative Phalen’s Test, negative Tinel’s Test at the wrist (and a positive Tinel sign at the pronator teres), and likely pain with resisted pronation. The Pronator Teres Syndrome Test would likely be positive. In addition, there may be history of repetitive pronation/supination such as with a person who plays racquet sports.

Assessment

Palpation

The pronator arises from the common flexor tendon at the medial epicondyle of the humerus. It passes obliquely from medial to lateral and forms the medial border of the cubital fossa. To palpate it, feel the antecubital fossa, most slightly medially, and pronate/supinate the forearm.

Strength

Patient is supine or sitting. The elbow should be held against the patients side or be stabilized by the examiner to avoid any shoulder abduction movement.

Test: Pronation of the forearm with the elbow partially flexed. Pressure: At the lower forearm , above the wrist (to avoid twisting the wrist), in the direction of supinating the forearm.

Treatment

Strengthening

In order to target the pronator teres specifically, the elbow should not be excessively flexed. If so, the muscle fibers will be shortened and less able to produce force. It is important to note that in the hammer pronation/supination video above, both the pronator and supinator groups work eccentrically, demanding more energy and strength. If this is too difficult or painful, consider eliminating the resistance, or a light band focusing on the concentric phase such as in the video below.

Manual therapy

Any number of manual therapy techniques can be appropriate for soft tissue mobilization to the pronator teres. It should be noted though, that the ulnar head is deep and will be more difficult to palpate. Also, if utilizing dry needling, caution should be taken to avoid the median nerve as it generally passes between the two heads.

See also

• Pronator Teres Syndrome Test
• Median Nerve
• Tinel’s Test
• Phalen’s Test
• Cubital Fossa