Sacrum caudal and thoracic vertebrae to form a single structure called the synsacrum. In the frog the ilium is elongated and forms a mobile joint with the sacrum that acts as an additional limb to give more power to its leaps. Sacrum The sacrum ( or ; plural: "sacra" or "sacrums"), in human anatomy, is a large, triangular bone at the base of the spine that forms by the fusing of sacral vertebrae S1S5 between 18 and 30years of age. The sacrum is situated at the upper, back part of the pelvic cavity, between the two wings of the pelvis. It
Body of sphenoid bone groove, in the angle between the body and greater wing, is a ridge of bone, called the sphenoidal lingula. The posterior surface, quadrilateral in form [Fig. 3], is joined, during infancy and adolescence, to the basilar part of the occipital bone by a plate of cartilage. Between the eighteenth and twenty-fifth years this becomes ossified, ossification commencing above and extending downward. The anterior surface of the body [Fig. 2] presents, in the middle line, a vertical crest, the sphenoidal crest, which articulates with the perpendicular plate of the ethmoid, and forms part of the nasal septum. On either side of