Brachialis

An elbow flexor beneath the biceps

Brachialis lies deep to biceps brachii in the anterior upper arm. It is a separate muscle, not another head of the biceps.

Use the isolated view to recognize its outline, then restore the surrounding models. Overlap is part of the anatomy: a muscle hidden from one viewpoint has not disappeared.

Sources: OpenStax anatomy

From the humerus to the ulna

Its origin occupies the lower anterior humeral surface and adjacent intermuscular septa. Distally, it attaches to the ulnar tuberosity and coronoid process.

Compare the destination bones: brachialis reaches the ulna, whereas biceps and brachioradialis reach the radius. Similar elbow actions do not mean identical attachments.

The humerus and ulna are both available in this page’s arm subset. Their named landmarks are not individually selectable, and the intermuscular septa are not modeled.

Sources: Loyola anatomy · Arm anatomy tables · Anatomy tables

Bending the elbow

Brachialis contributes to elbow flexion, bringing the forearm toward the upper arm. Study it alongside the other elbow flexors rather than treating the visible biceps as the only muscle performing that action.

Front, Back and Oblique change the camera. The bones remain in a fixed source pose; this study does not calculate muscle force or demonstrate a changing elbow angle.

Sources: Loyola anatomy · OpenStax anatomy

Main supply and a variable contribution

The musculocutaneous nerve provides the main motor supply. An additional radial-nerve contribution has been documented, with its distribution and relative contribution varying between specimens and studies.

Branches of the brachial artery supply brachialis. This is a summary of the named supply, not a complete map of its vascular network.

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

Sources: Loyola anatomy · Innervation study · Arm anatomy tables

Read the model

Explore brachialis in 3D

1. Inspect brachialis alone. Drag the selected muscle or use Oblique to compare its surfaces. Gold identifies the selection, not a contracting region.
2. Find the neighboring biceps. Choose Show context, then select Brachialis and enable Fade others. Compare it with the two biceps heads in the structure list; use the names to keep the separate muscles distinct.
3. Compare the destination bone. Switch between Ulna and Brachialis. Use Focus selection to inspect the proximal ulna; the attachment footprint is not outlined on the bone.
4. Continue at the elbow. The regional elbow study includes brachialis, brachioradialis and anconeus together. Select them there to compare their positions. 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, Brachialis

   Humeral and ulnar attachments, elbow action and nerve supply.

2. OpenStax — Anatomy and Physiology, section 11.5

   Relative position of brachialis and biceps, elbow flexors and attachment comparison. No source text or illustrations reproduced.

3. Bendersky & Bianchi — Double innervation of the brachialis muscle: anatomic-physiological study (2012)

   Abstract: anatomical and electrophysiological investigation of radial-nerve contribution. No frequency is generalized to every person.

4. Texas Tech University Health Sciences Center El Paso — Forearm & Wrist anatomy tables

   Brachioradialis row: radial attachment, for comparison with brachialis.

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

   Brachialis and anconeus rows: attachments, actions, nerve and arterial supply. Factual cross-check; no table or illustrations reproduced.

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