The true pelvis is made up of two halves, each formed by an innominate bone. Above these are the two ilium bones, also known as the wing or hip bones. The pelvis’s rear part consists of the sacrum, which is created by the fusion of five sacral vertebrae. The front part, the pubis, is formed by the merging of the two innominate bones. The ischial tuberosity is the back portion of the innominate bone and can be identified as a firm, bony bump at the center of the buttock.