Triceps brachii · medial head

A deeper head, not an absent one

The medial head occupies a deeper position on the lower posterior humerus. Overlying heads can obscure it in a surface view.

An isolated mesh makes that hidden shape easier to inspect, but it removes the relationships that explain its depth. Compare isolated and contextual views together.

Sources: Loyola anatomy

Lower humerus to proximal ulna

The medial head arises from the lower posterior humerus, inferomedial to the radial groove, with septal attachments. Distally it contributes to the triceps attachment at the olecranon.

Humerus and Ulna are selectable in this subset. The septa and separate tendon layers are not; the displayed boundary is the source mesh boundary, not a detailed dissection of those layers.

Sources: Loyola anatomy

Another contributor to straightening the elbow

The medial head participates in elbow extension alongside the other triceps heads. A deep position does not mean it has no mechanical contribution.

Rotating the model changes the viewpoint only. It does not move the joints, shorten muscle fibers or calculate how much force each head contributes.

The joint capsule is absent here. Its relationship with the muscle cannot be assessed from an empty gap or a flat surface in this model.

Sources: Arm anatomy tables

Connections outside the visible model

Radial-nerve branches provide motor supply, and deep brachial arterial branches contribute blood supply.

Nerves and vessels are not loaded in this subset, so the text describes connections you cannot select in the viewer.

Selecting this head does not select a nerve territory. The source asset contains no internal map of nerve entry points or vascular branches.

Sources: Arm anatomy tables

Read the model

Explore triceps brachii · medial head in 3D

1. Recognize the isolated shape. Choose Back, then Oblique. Rotate slowly to inspect the surfaces that can be covered by neighboring heads.
2. Restore its depth relationships. Choose Show context, select the medial head and enable Fade others. Compare it with the lateral and long heads without interpreting transparency as missing tissue.
3. Follow the distal context. Switch to Ulna, then back to the medial head. For a regional comparison, open the elbow study and select this head there. Open elbow study →

Sources and editorial status

This guide uses independently written explanations with links to the evidence behind them. Source checking and specialist anatomical review are separate steps; the latter is still pending.

1. Loyola University Chicago — LUMEN, Triceps

   Head-specific origins, ulnar attachment and elbow action. No source illustrations reproduced.

2. Texas Tech University Health Sciences Center El Paso — Axilla, Posterior Shoulder, & Arm

   Triceps row: head origins, elbow and long-head shoulder actions, radial nerve and deep brachial arterial supply.

3D geometry and its separate license are credited beneath the viewer. References do not imply endorsement of this site.