Overview
The anconeus is a short muscle that connects the ulna and humerus at the elbow. Even while the anconeus muscle is engaged during elbow extension, its role in the action itself is certainly very minimal. The primary muscle predominantly responsible for elbow extension is the triceps brachii. The anconeus muscle, on the other hand, allows forearm extension and supports the ulna as well as the capsule of the dorsal joint.Along with the brachioradialis, extensor carpi radialis longus, extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, and extensor carpi ulnaris muscles, the anconeus muscle is a member of the superficial extensor compartment.
Origin
The anconeus muscle is a triangular, short muscle situated at the elbow. It originates on the dorsal side of the humerus’s lateral epicondyle.The anconeus tendon extends medially and obliquely to form a broad muscle belly.
Insertion
The anconeus inserts at the lateral aspect of the olecranon of the ulna and runs along the proximal third of the ulna’s superior posterior aspect.
Nerve Supply
A motor branch of the radial nerve (C6-C8) originates in the radial sulcus of the humerus, travels via the medial head of the triceps, and eventually reaches the muscle distally and innervates the anconeus. The anconeus is a continuation of the triceps both morphologically and functionally. Both muscles are frequently mixed together, either entirely or partially, in addition to being innervated by the same nerve.
Blood Supply
There are three vascular pedicles supplying the anconeus muscle: the medial collateral artery, the posterior branch of the radial collateral artery, and the recurrent posterior interosseus artery.
Function/Action
Essentially, the triceps brachii muscle continues into the anconeus, which executes the same movement at the elbow. As a result, when it contracts, the forearm extends.
The anconeus is considered to have the added ability to abduct the ulna because of its lengthy connection to the bone, especially during forearm pronation movements. This movement is crucial for supporting the ulna and enabling the forearm to rotate during actions like using a screwdriver.
Additionally, the anconeus tightens the humeroulnar joint’s dorsal joint capsule to shield it from harm when the forearm is extended beyond it.
Clinical significance
The anconeus has a specific anatomical structure in 34% of all individuals. Despite the fact that the majority are safe, the anconeus epitrochlearis muscle is one variation that might be regarded as clinically important.
Unlike the “typical” variant, this muscle originates from the medial epicondyle of the humerus, crossing the ulnar groove of the humerus bone, where the ulnar nerve is present. Therefore, in cases of hypertrophy (such as in weightlifters), the anconeus epitrochlearis can compress the nerve, causing numbness in the little and ring fingers as well as elbow and forearm pain (cubital tunnel syndrome).
Right at and above the elbow, an anconeus trigger point generates discomfort. In this manner, tennis elbow might be developed.
Evaluation
Assessment of sensory changes in the ulnar nerve distribution (including pain, atrophy of the intrinsic muscles of the hand innervated by the ulnar nerve, and a neural provocation test of the ulnar nerve) is necessary for a precise diagnosis of cubital tunnel syndrome, which may be brought on by the hypertrophy of the anconeus muscle. Tests linking ulnar neuropathy to the elbow are utilized to confirm the diagnosis of cubital tunnel syndrome. To confirm the condition, these tests should produce provocative signals, such as symptoms being reproduced with elbow flexion, a positive Tinel’s sign test at the elbow, or a sign of instability, such as snapping of the ulnar nerve over the medial epicondyle with elbow flexion.
Treatment
Release of the trigger point that is producing the pain may be used to alleviate pain in the anconeus muscle, depending on the conditions.
