The muscles of the upper arm that are visible from the outside are the biceps brachii, the triceps brachii, the brachioradialis and the extensor carpi radialus longus. The coracobrachialis and brachialis are deeper upper arm muscles. The deltoid muscle is a shoulder muscle that increases the arm's range of motion.
The upper arm is the portion of the arm that extends from the shoulder joint to the elbow joint. All of the upper arm muscles except for the triceps muscle are on the anterior or front part of the arm. The triceps is the only muscle on the posterior or back of the arm.