The articularis cubiti is a small inconstant muscle deep to the medial head of the triceps that retracts the posterior elbow capsule during extension, preventing the synovial tissue from being pinched in the olecranon fossa. Analogous to the articularis genu at the knee, it is a capsule-protecting mechanism. When present it is also called the subanconeus muscle.
| Origin | Posterior distal humerus, a small muscle slip deep to the medial head of the triceps |
|---|---|
| Insertion | Posterior elbow joint capsule and olecranon fossa |
| Nerve Supply | Radial nerve (C7, C8) |
| Blood Supply | Superior ulnar collateral artery |
| Actions | Retracts the posterior elbow capsule during elbow extension preventing capsular impingement in the olecranon fossa |
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By actively pulling the posterior capsule proximally during elbow extension, it prevents the synovial fold from being crushed into the olecranon fossa, a mechanism that would cause synovitis and eventual arthrofibrosis with repeated impingement.
The articularis cubiti is encountered during posterior approaches to the elbow between the medial and lateral heads of triceps. Post-traumatic elbow stiffness involving posterior capsular adhesions may reflect failure of this muscle's protective retracting mechanism after haemarthrosis and immobilisation.
Not individually palpable due to its deep position under the triceps medial head.
Articularis cubiti failure allowing posterior capsular entrapment in the olecranon fossa during elbow extension contributing to post-traumatic elbow stiffness.
