The brachialis is an arm muscle located just above the elbow and beneath the bicep. Its primary purpose is to flex the elbow joint isometrically. The muscle works in conjunction with the bicep to provide elbow flexion. Although the bicep is often more active during flexion, the brachialis is actually the strongest muscle involved in this movement. Due to its location, the muscle is important in any sport or activity where the arm and elbow are used extensively such as tennis or squash.
The brachialis inserts at the ulna, a long bone in the lower arm and originates towards the front of the humerus. To attach to the bone, the muscle becomes a tendon before the ulna. For this reason brachialis tendinitis is an injury that’s common amongst people who overuse the muscle in a repetitive way. The muscle is part of the cubital fossa — a group of muscles located in the upper arm.
Any movement that requires the elbow to flex will involve the use of the brachialis as well as the bicep. Pushing, pulling and lifting with the arms will all invoke the muscle. The muscle also provides stability in the elbow against the triceps, which is important in movements such as throwing.
As the muscle is so commonly used in many sports it needs to be exercised regularly in order to increase flexibility and strength. Some athletes prefer to train the muscle in isolation while others use it in general arm exercises. Either way, to avoid injuries, exercises that use the muscle are vital. Although any movement that flexes the elbow will use the muscle, there are some which are more effective at training it than others.
Examples of exercises that can be used to train the brachialis muscle are barbell curls and cable curls. As the name suggests, to perform a barbell bicep curl the person should hold a barbell and flex the elbow while keeping his or her back straight. The movement should be slow and controlled. A cable curl is similar although a cable machine needs to be used.
Injuries to the muscles in the upper arm are common amongst weight lifters and body builders although they can affect anyone who uses elbow flexion in a repetitive way. For example, elbow tendinopathy and nerve entrapment syndrome are both caused by the overuse of this muscle.