| Definition: |
A subdivision of a limb or fin skeleton consisting of bones which connects the upper limb or fin to the axial skeleton on each side. It consists of the clavicle and scapula in humans and, in those species with three bones in the pectoral girdle, the coracoid. Some mammalian species (e.g. the dog and the horse) have only the scapula. In humans, the only joints between the shoulder girdle and axial skeleton are the sternoclavicular joints on each side. No joint exists between each scapula and the rib cage; instead the muscular connection between the two permits relatively great mobility of the shoulder girdle in relation to the pelvic girdle. In those species having only the scapula, no joint exists between the forelimb and the thorax, the only attachment being muscular[WP]. Examples: There are only two instances, right and left pectoral girdle skeletons. |