Anconeus

Anconeus muscle
Back of right upper extremity. (Anconeus labeled at bottom center.)
Posterior surface of the forearm. Superficial muscles. (Anconeus visible at center right.)
Details
Origin	lateral epicondyle of the humerus proximally
Insertion	lateral surface of the olecranon process and the superior proximal part of the posterior ulna
Artery	deep brachial artery, recurrent interosseous artery
Nerve	radial nerve (C7, C8, and T1)
Actions	It is partly blended in with the triceps, which it assists in extension of the forearm. It also stabilizes the elbow during pronation and supination and pulls sack out of the elbow joint capsule during extension to prevent impingement.
Identifiers
Latin	Musculus anconeus, musculus anconaeus
TA	A04.6.02.023
FMA	37704
Anatomical terms of muscle []

The anconeus muscle (or anconaeus/anconæus) is a small muscle on the posterior aspect of the elbow joint.

Some consider anconeus to be a continuation of the triceps brachii muscle. Some sources consider it to be part of the posterior compartment of the arm, while others consider it part of the posterior compartment of the forearm.

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

Anconeus originates on the posterior surface of the lateral epicondyle of the humerus and inserts distally on the posterior surface of the ulna.

Anconeus is innervated by a branch of the radial nerve (cervical roots 7 and 8) from the posterior cord of the brachial plexus called the nerve to the anconeus. The somatomotor portion of radial nerve innervating anconeus bifurcates from the main branch in the radial groove of the humerus. This innervation pattern follows the rules of innervation of the musculature of the posterior forearm (extensor) compartment by the radial nerve.

Its role in elbow extension is trivial in humans. It assists in extension of the elbow, where the triceps brachii is the principal agonist, and supports the elbow in full extension. It also prevents the elbow joint capsule being pinched in the olecranon fossa during extension of the elbow. Anconeus also abducts the ulna and stabilizes the elbow joint. Anconeus serves to make minute movements with the radius on the ulna. In making slight abduction of the ulna, it allows any finger to be used as an axis of rotation of the forearm.

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

Trauma to the nerve supply of the anconeus muscle can usually result from a shoulder dislocation or fractures of the upper part of the humerus or around the olecranon, or any injury that damages the radial nerve. Harm inflicted upon the radial nerve through these mechanisms can paralyze the anconeus muscle as well as other extensors of the elbow and wrist. There are no specific acquired injuries that exclusively affect the anconeus muscle; however, any disease that compromises muscular functions, particularly arm extension (i.e. muscular dystrophy) will affect this particular accessory muscle. Heterotopic ossification can result from certain trauma as it is an abnormal growth of osseous tissue in non-osseous tissue (e.g. muscle tissue). The condition is usually found in the hips, although there have been documented cases of certain individuals with it occurring in the arms and legs. The cause for the process to initiate is not well understood, only that it typically results from surgery or trauma.