Sex differences in human physiology pelvis is, in general, different between the human female and male skeleton. It differs both in overall shape and structure. The female pelvis, adapted for gestation and childbirth, is less high, but proportionately wider and more circular than in the male; its sacrum—the triangular bone at the upper posterior of the pelvic cavity, serving as base of the spine—is also wider. The female pelvis is tilted anteriorly, often resulting in the more sway-backed appearance. In the female, the acetabula, the concave surfaces to which the balls of the femurs attach via ligaments, are located farther apart, which increases the distance
Bone tumor known to occur occasionally, current paradigms tend to consider MFH a "wastebasket" diagnosis, and the current trend is toward using specialized studies (i.e. genetic and immunohistochemical tests) to classify these undifferentiated tumors into other tumor classes. Multiple myeloma is a hematologic cancer, originating in the bone marrow, which also frequently presents as one or more bone lesions. Germ cell tumors, including teratoma, often present and originate in the midline of the sacrum, coccyx, or both. These sacrococcygeal teratomas are often relatively amenable to treatment. Since, by definition, benign bone tumors do not metastasize, all secondary bone tumors are metastatic lesions