Brachialis muscle
muscle of the upper limb
The brachialis (also brachialis anticus or Casserio muscle) is a muscle in the upper arm that flexes the elbow. It lies beneath the biceps brachii, and makes up part of the floor of the region known as the cubital fossa (elbow pit). It originates from the anterior aspect of the distal humerus; it inserts onto the tuberosity of the ulna. It is innervated by the musculocutaneous nerve, and commonly also receives additional innervation from the radial nerve. The brachialis is the prime mover of elbow flexion generating about 50% more power than the biceps.
Structure
Origin
The brachialis originates from the anterior surface of the distal half of the humerus, near the insertion of the deltoid muscle, which it embraces by two angular processes. Its origin extends below to within 2.5 cm of the margin of the articular surface of the humerus at the elbow joint.
Insertion
Its fibers converge to a thick tendon which is inserted into the tuberosity of the ulna, and the rough depression on the anterior surface of the coronoid process of the ulna.
Innervation
The brachialis muscle is innervated by the musculocutaneous nerve (also Casserio nerve), which runs on its superficial surface, between it and the biceps brachii. However, in 70-80% of people, the muscle has double innervation with the radial nerve (C5-T1).
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This entry incorporates text from “Brachialis muscle” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.