Importantly, with the thumb positioned at right angles to the palm, only a slight rotation of metacarpal I on the wrist brings the pad of the thumb into a position directly facing the pads of the other fingers. This opposition of the thumb is essential for normal hand function.
The shoulder is the region of upper limb attachment to the trunk.
The bone framework of the shoulder consists of: the clavicle and scapula, which form the pectoral girdle (shoulder girdle), and the proximal end of the humerus.