Articulates above with 5th lumbar vertebra. Iliac bones join to form pelvic girdle. They form a slightly movable joint. They attach to the sacrum via a small intervertebral disc. Floor of cage is diaphragm.
Anterior wall is costal cartilages and sternum.
Cage encloses and protects vital organs and provides support for bones of shoulder girdle. Movement is important for respiration. Joins with sternal body with hinge joint that allows movement during respiration. Sternal body connected to 6 ribs. Xiphoid process may have a bunch of forms.