Upper Back Muscles. The deltoid, teres major, teres minor, infraspinatus, supraspinatus (not shown) and subscapularis muscles (not shown) all extend from the scapula to the humerus and act on the shoulder joint.
An upper arm muscle composed of 2 parts, a long head and a short head. This muscle flexes the elbow and shoulder as well as supinates the forearm (i.e. rotates the forearm so the palm is facing the ceiling).
Major Muscles on the Front of the Body. Sometimes the name of the muscle includes it’s function—such as extensor, flexor, adductor, abductor. The muscles on the front of the trunk help lift the arms and move the body forward and sideways. They also protect the organs in the abdomen.