Triceps Long Head

caput longum m. tricipitis brachii detail

The long head is the only head with a scapular origin, making it a two-joint muscle. Its infraglenoid origin is the reference for the triangular and quadrilateral spaces that transmit the axillary nerve and posterior circumflex humeral artery.

Nerve: Radial nerve (C6, C7, C8) — branch arising… Blood Supply: Deep brachial artery Region: Upper Arm

Anatomical Data

Origin, Insertion & Supply

Origin	Infraglenoid tubercle of the scapula
Insertion	Posterior olecranon via the common triceps tendon
Nerve Supply	Radial nerve (C6, C7, C8) — branch arising in the axilla
Blood Supply	Deep brachial artery

Biomechanics

Function & Actions

Actions	Extends the elbow; Adducts and extends the shoulder via its scapular origin

Clinical Relevance

Clinical Notes

Triceps long head origin at the infraglenoid tubercle is the border of the quadrilateral space. Tendinopathy here produces posterior shoulder pain reproduced by resisted elbow extension with shoulder flexion.

Palpation

Palpable on the posterior arm as the medial belly during resisted elbow extension.

Pathology

Common Injuries & Conditions

Triceps Long Head Infraglenoid Tendinopathy

Traction enthesopathy at the infraglenoid tubercle producing posterior shoulder pain in overhead athletes, managed by eccentric loading rehabilitation.