Brachialis (left) (Musculus brachialis)
Educational content only — not medical advice.
Anatomy
Lies deep under biceps brachii and is the "workhorse" of elbow flexion: a pure flexor with no rotational role, stronger than biceps in pure flexion, its distal tendon covering the joint capsule and cushioned by the articular bursa.
Origin & insertion
Lower half of the anterior humeral shaft and both intermuscular septa. Ulnar tuberosity and the anterior surface of the coronoid process.
Action
Flexes the forearm at the elbow in every forearm position (pronated or supinated) — the prime mover.
Innervation
Musculocutaneous nerve (C5–C6), with a small radial branch to its inferolateral part.
Clinical notes
Biceps tendon rupture does not abolish elbow flexion because the brachialis remains intact — a classic differential test; strength imbalance after surgery alters the elbow flexion axis.
Related structures
Educational references
FAQ
What is the role of the Brachialis (left)?
Lies deep under biceps brachii and is the "workhorse" of elbow flexion: a pure flexor with no rotational role, stronger than biceps in pure flexion, its distal tendon covering the joint capsule and cushioned by the articular bursa.
Why is the Brachialis (left) clinically important?
Biceps tendon rupture does not abolish elbow flexion because the brachialis remains intact — a classic differential test; strength imbalance after surgery alters the elbow flexion axis.
Source & license
BodyParts3D, © The Database Center for Life Science licensed under CC Attribution 4.0 International (https://creativecommons.org/licenses/by/4.0/). license details