Origin and Insertion (Structure)
The anatomical structure of the anconeus muscle is defined by the following attachment sites:
- Origin (Origo): muscle fibers originate from the posterior surface of the lateral epicondyle of the humerus (epicondylus lateralis). An additional fixation point is the radial collateral ligament (lig. collaterale radiale).
- Insertion (Insertio): the muscle runs distally and inserts onto the posterolateral surface of the ulna (ulna). The insertion site is located at the base of the olecranon (olecranon).
Function of the Anconeus Muscle
In upper limb biomechanics, the m. anconeus performs two primary roles:
- Forearm extension: the muscle assists in extending the forearm at the elbow joint, acting as a weak synergist to the triceps brachii (m. triceps brachii).
- Capsule tension: the anconeus pulls on the joint capsule to prevent it from being pinched during extension.
According to classical classification, the anconeus belongs to the posterior muscle group of the arm (extensors). This group also includes the triceps brachii and the articularis cubiti muscle (m. articularis cubiti).
Blood Supply and Innervation
- Blood supply: the muscle is supplied by the recurrent interosseous artery (a. interossea recurrens), a branch of the posterior interosseous artery (a. interossea posterior). Additional blood supply is derived from collateral arterial branches.
- Innervation: the muscle is innervated by the radial nerve (n. radialis), receiving fibers from spinal segments C7–C8.
Topography and Syntopy of the Elbow Joint
The anconeus muscle is a key structure of the posterior elbow region:
- Relation to the joint capsule: the posterior joint capsule is unevenly covered. The superior part is covered by the tendon of the triceps brachii, while the inferolateral part is covered by the anconeus (m. anconeus). Medially, the capsule is unprotected by muscles and covered only by deep fascia and skin.
- Adjacent structures: in dissections of the posterior elbow region, the muscle is visualized near the posterior border of the ulna (margo posterior ulnae), brachial fascia (fascia brachii), and subcutaneous olecranon bursa (bursa subcutanea olecrani). The posterior cutaneous nerve of the forearm (n. cutaneus antebrachii posterior) is also located in this zone.
- Cross-section: at the level of the elbow joint, the m. anconeus is identified alongside the triceps brachii tendon, olecranon, lateral epicondyle, extensor carpi radialis longus (m. extensor carpi radialis longus), and brachioradialis (m. brachioradialis).
- Forearm layers: on anatomical diagrams of the forearm, the anconeus is visualized bridging the superficial and deep layers of the posterior region.