Ilium (bone) "ilis"), meaning "groin" or "flank". The ilium consists of the body and wing. Together with the ischium and pubis, to which the ilium is connected, these form the pelvic bone, with only a faint line indicating the place of union. The body () forms less than two-fifths of the acetabulum; and also forms part of the acetabular fossa. The internal surface of the body is part of the wall of the lesser pelvis and gives origin to some fibers of the obturator internus. The wing () is the large expanded portion which bounds the greater pelvis laterally. It has an
Mastoid part of the temporal bone be distinguished from the mastoid cells, though it communicates with them. Like the mastoid cells it is filled with air and lined by a prolongation of the mucous membrane of the tympanic cavity, with which it communicates. The tympanic antrum is bounded above by a thin plate of bone, the tegmen tympani, which separates it from the middle fossa of the base of the skull; below by the mastoid process; laterally by the squama just below the temporal line, and medially by the lateral semicircular canal of the internal ear which projects into its cavity. It opens in front into