Sacrum

(sa’ - krum) [sacer, sacred; os, bone, understood]. A curved triangular bone composed of five united vertebrae, situated between the last lumbar vertebra above, the coccyx below, and the two o a in no min at a on either side, and forming the posterior boundary of the pelvis. Saddle-joint. An articulation in which each surface is concave in one direction and convex in the other. Saddle-nose. A nose of which the bridge is sunken in. 562