Medial Head of Triceps Tendon

tendo capitis medialis musculi tricipitis brachii

The medial head of triceps is the deepest head, originating from a wide area of the posterior humeral shaft below the radial groove that extends almost to the elbow, the largest origin of the three heads. Its fibres form the deep layer of the distal triceps and merge with the common tendon inserting on the olecranon. The medial head is the primary elbow extensor during slow, unloaded extension.

Anatomical Data

Attachments

Muscle	Triceps brachii (medial head)
Attachment	Posterior surface of the humerus below the radial groove, extending almost to the elbow, and the medial and lateral intermuscular septa

Biomechanics

Function & Actions

Extends the elbow and is active in all elbow extension

Clinical Relevance

Clinical Notes

In distal triceps ruptures the superficial layer formed by the long and lateral heads usually tears first, and an intact deep medial head layer can preserve some active extension and mask the injury. Snapping triceps syndrome involves the medial head subluxating over the medial epicondyle during elbow flexion, often accompanied by ulnar nerve subluxation. In the posterior approach to the humerus the medial head is elevated from the shaft to allow plate fixation, and the radial nerve and profunda brachii run in the radial groove just above its origin.

Pathology

Common Injuries & Conditions

Snapping Medial Triceps

Subluxation of the medial triceps head over the medial epicondyle producing a painful snap at the posteromedial elbow during elbow flexion, often coexisting with ulnar nerve subluxation.

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