Anconeus muscle


Image by/from Henry Vandyke Carter

The anconeus muscle (or anconaeus/anconaus) is a little muscle on the posterior area of the elbow joint.

Some consider anconeus to be an extension of the triceps brachii muscle. Certain resources consider it being a part of the posterior compartment of the arm, while others think of it part of the posterior compartment of the forearm.

The anconeus muscle can quite easily be palpated just lateral to the olecranon process of the ulna.

Anconeus originates on the posterior surface area of the lateral epicondyle of the humerus and inserts distally upon the superior posterior surface of the ulna and the lateral part of the olecranon.

Anconeus is innervated by a division of the radial nerve (cervical roots 7 and 8) from the posterior cord of the brachial plexus referred to as the nerve to the anconeus. The somatomotor part of radial nerve innervating anconeus bisect from the primary branch in the radial groove of the humerus. This innervation pattern adheres to the guidelines of innervation of the musculature of the posterior forearm (extensor) compartment by the radial nerve.

Its function in elbow extension is minor in people. It helps in extension of the elbow, where the triceps brachii is the primary agonist, and assists the elbow in complete extension. It likewise stops the elbow joint capsule being pinched in the olecranon fossa throughout extension of the elbow. Anconeus likewise abducts the ulna and supports the elbow joint. Anconeus helps to produce slight motions with the radius on the ulna. In helping make small abduction of the ulna, it enables any finger to be utilized as an axis of rotation of the forearm.

Anconeus is supplied by the middle collateral artery from the profunda brachii artery.

Injury to the nerve supply of the anconeus muscle can often arise from a shoulder dislocation or bone fractures of the upper aspect of the humerus or surrounding the olecranon, or any trauma that harms the radial nerve. Damage delivered upon the radial nerve through these mechanisms can paralyze the anconeus muscle along with other extensors of the elbow and wrist. There are no particular acquired injuries that specifically impact the anconeus muscle; nevertheless, any illness that jeopardizes muscular functions, especially arm extension (i.e. muscular dystrophy) will impact this specific accessory muscle. Heterotopic ossification can arise from specific injury as it is an irregular expansion of osseous tissue in non-osseous tissue (e.g. muscle tissue). The condition is generally experienced in the hips, although there have actually been recorded cases of some people with it taking place in the limbs. The root cause for the process to start is not well comprehended, just that it usually arises from surgical treatment or injury.

Anconaeus is taken from the ancient Greek noun, agkon. ‘Akon can be transcribed as bend of the arm or elbow. The phrase musculus anconaeus was transcribed into English as elbow muscle in 1907 in the English translation of the 1st edition of the Nomina Anatomica.

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