The brachialis muscle is located in the upper arm, where it lies beneath the biceps muscle. It acts as a structural connection between the humerus, which is the bone of the upper arm, and the ulna, which is the bone of the forearm. The muscle is innervated by the musculoskeletal nerve and partly by the radial nerve. In some people, the muscle may appear doubled. Also called the brachialis anticus, the most acknowledged function of the muscle is its ability to flex the elbow. Due to its high contractile ability, many arm and elbow movements are made possible. Such movements are highly important in the successful performance of activities of daily living. Because movements involving the arms and elbows are almost always continuous, injuries to the brachialis muscle are quite common. They can be as subtle as muscle aches or as severe as muscle rupture and hematoma. The muscle can tear, lacerate or rupture with overextension of the elbow or when extreme force is exerted against surrounding structures. The muscle can also experience strains during overwhelming and sudden weight lifting exercises.
Written and medically reviewed by the Healthline Editorial Team
In Depth: Brachialis