os sacrum

sa·crum

, pl.

sa·cra

(sā'krŭm, sā'kră), [TA]

The segment of the vertebral column forming part of the pelvis; a broad, slightly curved, spade-shaped bone, thick above, thinner below, closing in the pelvic girdle posteriorly; it is formed by the fusion of five originally separate sacral vertebrae; it articulates with the last lumbar vertebra, the coccyx, and the hip bone on either side.

Synonym(s): os sacrum [TA], sacred bone, vertebra magna

[L. (lit. sacred bone), neuter of sacer (sacr-), sacred]

os sacrum

; sacrum vertebral column segment forming part of the pelvis and closing the posterior portion of the two halves of the pelvic girdle; formed from fusion of five sacral vertebrae (S1-S5); articulates superiorly with fifth lumbar vertebra (L5), inferiorly with the coccyx, and laterally with hip bones