In general, limbs are the paired appendages of the body that are used for grasping or for locomotion. The upper limbs of the body, which are located above the waist, function in grasping. In other species, such as the gorilla, the upper limbs also participate in locomotion. In humans, the upper limbs are the two arms, including the forearm and the hand, and their components (bones, muscles, blood vessels, and nerves).

Each upper limb begins at the shoulder. The main skeletal support is the scapula. The eight muscles located there reflect the high degree of mobility of the shoulder. These muscles power the up-down, side-to-side and rotational movement of the shoulder.

The arm runs from the shoulder to the elbow. Skeletal support is provided by one large bone called the humerus. There are four main muscles in the upper arm. These are the biceps...