Mammal, pectoral girdle (Gross, Medium)

Structure List Scapula (pectoral girdle) Humerus Ribs Vertebrae Sternum Low Magnification View

Because the girdles of terrestrial vertebrates transfer body weight to the appendages and receive the thrusts of the legs, they must be strong. The attachment of the pectoral girdle to the skull becomes lost in primitive tetrapods for what obvious reason? Allows head and trunk to move independently. A terrestrial vertebrate does not have a direct skeletal attachment between the PECTORAL GIRDLE and the vertebral column. Weight is transferred from the vertebral column to the scapula by a muscular sling. Note that in the dog or cat you could cut the entire foreleg and shoulder off without ever cutting through a bone! It is important for the pelvic girdle to be attached to the axial skeleton, but the irregular and weak attachment of the pectoral girdle to the axial skeleton suggests that this is much less important, structurally. Can you think of any good reason for this?