Innominate.—The innominate bone, commonlyknown as the hip, is a large, irregularly shaped bonecomposed of three parts: the ilium, ischium, and pubis(fig. 1-23). In children these three parts are separatebones, but in adults they are firmly united to form acuplike structure, called the acetabulum, into whichthe head of the femur fits. The ilium forms the outerprominence of the hip bone (the crest of the ilium,referred to as the iliac crest, provides an anatomicallandmark above the ilium); the ischium forms the hardlower part; and the pubis forms the front part of thepelvis.Symphysis Pubis.—The area where the two pubicbones meet is called the symphysis pubis and is oftenused in anatomical measurements. The largestforamen, or opening, is located in the hip bone,between the ischium and the pubis, and is called theobturator foramen (fig. 1-23). The crest of the iliumis used in making anatomical a n d s u rg i c a lmeasurements (e.g., location of the appendix, which isapproximately halfway between the crest of the iliumand the umbilicus).Femur.—The femur, or thigh bone, is the longestbone in the body (fig. 1-24). The proximal end isrounded and has a head supported by a constricted neck1-14HM3F0123ILIACCRESTSACRUMACETABULUMOBTURATORFORAMENSYMPHYSISPUBISISCHIUMCOCCYXILIUMFigure 1-23.—Pelvic girdle.GREATERTROCHANTERLESSERTROCHANTERFEMURPATELLAFIBULATIBIAMETATARSALSPHALANGESTARSALHM3f0124Figure 1-24.—Anterior view of the right leg.BONECOMMONNAMETOTALNUMBERIN BODYinnominatehip bone 2femurthigh bone 2patellaknee cap 2tibialeg bone 2fibulaleg bone 2tarsalsankle bones 14metatarsalsfoot bones 10phalangestoe bones 28Table 1-2.—Bones of the Lower Extremities
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