The human skeletal system can be divided into axial skeleton that consists of 80 bones and an appendicular skeleton that consists of 126 bones. The axial skeleton consists of those bones that are seen in the axis of the body. The appendicular skeleton consists of the bones of girdles and limbs. The pectoral girdle is the upper girdle and it consists of four bones These include two clavicles and two scapulas. The clavicle is the collar bone. It is the only horizontal bone present in the body. It articulates medially with sternum and distally with acromion process of scapula. The scapula is the shoulder blade and is present on the back. This is a flat triangular bone that extends from second to seventh ribs. This consists of a glenoid cavity which articulates with head of the humerus to form the shoulder joint.