Brachialis Muscle, Anterior View

Description

Anteriorly, the brachialis occupies the distal half of the anterior humerus, its broad muscle belly lying deep to the biceps brachii and converging into a stout tendon toward the proximal ulna. Medially and laterally, its fibers arise from the anteromedial and anterolateral surfaces of the humeral shaft and adjacent intermuscular septa, framing the anterior aspect of the elbow. Distally, the tendon passes deep to the bicipital aponeurosis to insert on the ulnar tuberosity and coronoid process, immediately anterior to the elbow joint capsule. Pure elbow flexor. Because brachialis acts across the humeroulnar joint without contributing to forearm supination, it remains the most consistent generator of elbow flexion torque regardless of whether the forearm is pronated or supinated. That distinction matters when localizing weakness in C5 to C6 radiculopathy or musculocutaneous nerve lesions, where biceps strength may vary with forearm position but brachialis-driven flexion should still be assessable. Surgeons also use this anatomy when developing an anterior approach to the distal humerus and elbow, splitting brachialis to reach the joint while respecting the nearby course of the musculocutaneous nerve and brachial artery in the anterior compartment. Faculty will find this anterior arm view useful for upper-limb anatomy labs, kinesiology modules on elbow mechanics, and exam figures contrasting biceps brachii versus brachialis function. It also fits orthopedic and sports medicine publications discussing distal biceps rupture, elbow flexor testing, and anterior elbow pain syndromes where brachialis strain can mimic biceps pathology. Anatomical accuracy verified by SciePro's Medical Advisory Board.