The appendicular skeleton's upper extremity is made up of four main components:
- The Shoulder Support: The scapula, or shoulder blade, and the clavicle, or collar bone, make up the shoulder girdle. The shoulder girdle is attached to the axial skeleton by the clavicle, and the upper arm bone is attached by the scapula.
- Bone of the Upper Arm: The humerus, or upper arm bone, connects the forearm bones to the shoulder girdle. It serves as an attachment point for the muscles that move the shoulder and elbow joints and is the longest bone in the upper extremity.
- The Bones of the Arm: The radius and ulna are the two long bones that make up the forearm. The ulna is on the medial side of the forearm, whereas the radius is on the lateral side. The wrist and hand can move because of these bones.
- The Finger: The wrist, palm, and fingers make up the hand. The eight carpal bones, which allow the hand to move, are located in the wrist. Five metacarpal bones connect the fingers to the wrist on the palm. Except for the thumb, which only has two phalanges, each finger is made up of three bones called phalanges.