The ilia are not connected with the sacrum by ossified sacral ribs.
Distance from acetabular axis to anterior end of sacrum 30 mm.
The former is one of the amphiarthroses or half-joints by which the sacrum is bound to the ilium.
The ossification of the sacrum also has reached its culminating point.
The bone immediately below the sacrum, called the coccyx, is essentially the representative of the tail in man.
The structure so formed may be named the notarium to distinguish it from the sacrum.
Each half is firmly united to its fellow in a ventral symphysis behind, and is in front expanded and united to the sacrum.
They are united to the sacrum behind and joined to each other in front.
But the joints of the backbone in front of the sacrum receive their air from the cervical air sac.
Also note how much longer and more solid the sacrum (with its attached bone, called the coccyx) is in the male pelvis.
bone at the base of the spine, 1753, from Late Latin os sacrum "sacred bone," from Latin os "bone" (see osseous) + sacrum, neuter of sacer "sacred" (see sacred). Said to be so called because the bone was the part of animals that was offered in sacrifices. Translation of Greek hieron osteon. Greek hieros also can mean "strong," and some sources suggest the Latin is a mistranslation of Galen, who was calling it "the strong bone."
sacrum sa·crum (sā'krəm, sāk'rəm)
n. pl. sa·cra (sā'krə, sāk'rə)
The triangular segment of the spinal column that forms part of the pelvis and closes in the pelvic girdle posteriorly, is formed between the ages of 16 and 25 by the fusion of five originally separate sacral vertebrae, and articulates with the last lumbar vertebra, the coccyx, and the hipbone on either side.
A triangular bone at the base of the spine, above the coccyx (tailbone), that forms the rear section of the pelvis. In humans it is made up of five vertebrae that fuse together by adulthood. See more at skeleton.