The anconeus is a small triangular muscle at the posterolateral elbow that assists elbow extension and provides lateral elbow stability. Its unique role in abducting the ulna during pronation — drawing the lateral olecranon outward to accommodate the radial head displacement — makes it a dynamic posterolateral stabiliser. The anconeus is used as a pedicled muscle flap for proximal ulna coverage after olecranon reconstruction.
| Origin | Posterior lateral epicondyle of the humerus |
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| Insertion | Lateral surface of the olecranon and posterior proximal ulna |
| Nerve Supply | Radial nerve (C7, C8) — a branch given off in the spiral groove before the lateral intermuscular septum |
| Blood Supply | Posterior interosseous artery and recurrent interosseous artery |
| Actions | Elbow extension (minor — assists triceps); Lateral elbow stabilisation during varus loads; Abducts the ulna during forearm pronation — a unique rotational role |
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The anconeus is used as a pedicled rotational flap for soft tissue coverage of the proximal ulna and posterior elbow, based on the recurrent posterior interosseous artery. Its harvest does not significantly weaken elbow extension.
The anconeus is palpable as a triangular muscle at the posterolateral elbow between the lateral epicondyle and the proximal ulna, becoming firm during resisted elbow extension.
Rare isolated anconeus compartment syndrome from posterior elbow trauma producing compartment pressure elevation managed with isolated compartment fasciotomy.
