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Pronator Teres Muscle Anatomy

The pronator teres, a fusiform muscle, is the most lateral of the superficial forearm flexors. Its lateral border forms the medial boundary of the cubital fossa.

It is one of 4 muscles located in superficial layer of the anterior compartment of the forearm. The superficial layer of the anterior compartment of the forearm contains the following:

  1. Pronator teres,
  2. Flexor carpi radialis,
  3. Palmaris longus,
  4. Flexor carpi ulnaris.

These muscles are all attached proximally by a common flexor tendon to the medial epicondyle of the humerus, the common flexor attachment.

See Also: Forearm Muscles Anatomy & Function

Pronator Teres Muscle Anatomy

Origin: The pronator teres has two heads:

  • Humeral head: Originates from the medial epicondyle of the humerus.
  • Ulnar head: Originates from the coronoid process of the ulna.

Insertion: The muscle fibers insert into the lateral surface of the midshaft of the radius.

Innervation: This muscle is innervated by the median nerve, which is a crucial nerve of the upper limb, providing motor and sensory innervation to parts of the forearm and hand.

Blood Supply: The muscle receives blood from the ulnar artery, ensuring it has a consistent supply of oxygen and nutrients necessary for its function.

See Also: Hand Nerves and Blood Supply

Function: The primary function of the PT muscle is to pronate the forearm. Pronation refers to the rotational movement where the palm of the hand is turned to face downwards. This action is essential for various daily activities, such as turning a doorknob or using a screwdriver.

In addition to pronation, the PT muscle assists in flexing the forearm at the elbow joint. This dual function makes it a key player in the coordination of arm movements.

OriginMedial epicondyle of humerus and coronoid process of ulna
InsertionMiddle of lateral surface of radius
InnervationMedian nerve (C6, C7)
Blood SupplyUlnar artery, anterior recurrent ulnar artery
ActionPronates and flexes forearm (at elbow)
Pronator Teres Muscle Anatomy

The proposed Pronator Teres Muscle variations are:

  1. short and tendinous ulnar head,
  2. ulnar head joined to the arch of the flexor digitorum superficialis muscle,
  3. ulnar head with triple origin slips,
  4. humeral head perforated by the median nerve.

Clinical Significance

Understanding the pronator teres anatomy is important in diagnosing and treating various conditions related to the forearm and elbow.

  • Pronator Teres Syndrome: This is a condition where the median nerve is compressed as it passes between the two heads of the pronator teres muscle. Symptoms may include pain in the forearm and numbness or tingling in the hand, mimicking carpal tunnel syndrome.
  • Muscle Strain: Overuse or trauma can lead to strain or injury of the pronator teres, resulting in pain and limited movement in the forearm.
  • Medial epicondylitis: also known as golfer’s elbow, is a condition characterized by pain along the medial aspect of the elbow. The pain often has an insidious onset and is worsened by forearm pronation or wrist flexion. The pronator teres is often implicated as a source of pathology in this condition.
  • Median Nerve Entrapment: Since the median nerve runs through the pronator teres, any inflammation or hypertrophy of the muscle can lead to nerve entrapment, causing sensory and motor deficits in the hand and forearm.
See Also: Pronator Teres Syndrome
See Also: Medial Epicondylitis

To test the pronator teres, the person’s forearm is flexed at the elbow and pronated from the supine position against resistance provided by the examiner. If acting normally, the muscle is prominent and can be palpated at the medial margin of the cubital fossa.

References & More

  1. Clinically Oriented Anatomy – 8th Edition
  2. Luxenburg D, Rizzo MG. Anatomy, Shoulder and Upper Limb, Pronator Teres. [Updated 2023 May 1]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Pubmed
  3. Dididze M, Tafti D, Sherman Al. Pronator Teres Syndrome. [Updated 2023 Jul 3]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Pubmed
  4. Nebot-Cegarra J, Perez-Berruezo J, Reina de la Torre F. Variations of the pronator teres muscle: predispositional role to median nerve entrapment. Arch Anat Histol Embryol. 1991-1992;74:35-45. PMID: 1366347. Pubmed
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