Upper limb

Triceps Brachii, Medial Head

Musculus triceps brachii (caput mediale)

Origin

Posterior surface of the humerus, distal to the radial groove (distal two-thirds)

Insertion

Olecranon of the ulna (common triceps tendon)

Function

Extends the elbow

Innervation

Radial nerve, C7–C8

Movement & chain

The 'workhorse' of the triceps: as the deepest head, it is active throughout nearly the entire range of motion, including low-intensity elbow extension.

Palpation

Mostly covered by the other two heads; only distally, just proximal to the olecranon, is it directly palpable.

Clinical

An isolated injury is rare, as the head is largely covered and protected by the lateral and long heads; being a 'reserve' head, it is recruited mainly with increasing resistance.

Segmental innervation

Radial nerve, C7–C8.

In clinical practice

Safe transfer techniques avoiding arm traction (prevents shoulder subluxation in stroke patients); monitor injection sites and offload scapular pressure.

Region in the model

Upper limb