Upper limb

Triceps Brachii, Long Head

Musculus triceps brachii (caput longum)

Origin

Infraglenoid tubercle of the scapula

Insertion

Olecranon of the ulna (common triceps tendon)

Function

Extends the elbow; also extends and adducts the shoulder (crosses both joints)

Innervation

Radial nerve, C7–C8

Movement & chain

The only two-joint triceps head: it assists shoulder extension/adduction (for example pulling the arm downward) in addition to elbow extension.

Palpation

Palpable in the middle of the posterior upper arm, between the lateral and medial heads, most proximally toward the axilla.

Clinical

Involved in quadrilateral space syndrome, as the long head partly forms the border of this space, where the axillary nerve can become compressed.

Segmental innervation

Radial nerve, C7–C8.

In clinical practice

The long head, together with teres minor and teres major, borders the quadrilateral space, relevant to recognizing neurovascular entrapment around the axilla.

Region in the model

Upper limb