Anconeus muscle

The anconeus is a small triangular muscle located on the posterolateral aspect of the elbow joint. Often considered a continuation of the triceps brachii, it plays a subtle yet important role in elbow function.

Origin

The anconeus muscle arises by a separate tendon from the posterior aspect of the lateral epicondyle of the humerus.

Insertion

From its origin, the muscle fibers extend obliquely downward and medially to insert onto the ulna, specifically on the lateral surface of the olecranon process and the superior part of the posterior surface of the ulna.

Artery

It receives its blood supply from the profunda brachii artery and the interosseous recurrent artery (a branch of the posterior interosseus artery)

Nerve

The radial nerve (C7, C8, and T1)

Actions

While considered a weak elbow extensor, the anconeus muscle primarily assists the triceps in forearm extension. Its key roles include stabilizing the elbow joint and abducting the ulna during pronation. Due to its close relation to the lateral joint capsule, it also prevents the capsule from being pinched in the olecranon fossa during elbow extension. Functionally, it contributes significantly to posterolateral elbow stability, acting as an active dynamic stabilizer of the humeroulnar joint, particularly in response to varus stress.