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
Sacrum κλόνις (Latinized "clonis"); this term is cognate to Latin "clunis" "buttock", Sanskrit "" "haunch" and Lithuanian "šlaunis" "hip, thigh". The Latin word is found in the alternative Latin name of the sacrum, "ossa clunium", as it were "bones of the buttocks". Due to the fact that the os sacrum is broad and thick at its upper end, the sacrum is alternatively called "os latum", "broad bone". In dogs the sacrum is formed by three fused vertebrae. The sacrum in the horse is made up of five fused vertebrae. In birds the sacral vertebrae are fused with the lumbar and some