Hip bone is easily located through the skin. The iliac crest shows clear marks of the attachment of the three abdominal wall muscles. The ischium forms the lower and back part of the hip bone and is located below the ilium and behind the pubis. The ischium is the strongest of the three regions that form the hip bone. It is divisible into three portions: the body, the superior ramus, and the inferior ramus. The body forms approximately one-third of the acetabulum. The ischium forms a large swelling, the tuberosity of the ischium, also referred to colloquially as the "sit bone". When
Parietal bone granulations (Pacchionian bodies). In the groove is the internal opening of the parietal foramen when that aperture exists. The parietal bone is ossified in membrane from a single center, which appears at the parietal eminence about the eighth week of fetal life. Ossification gradually extends in a radial manner from the center toward the margins of the bone; the angles are consequently the parts last formed, and it is here that the fontanelles exist. Occasionally the parietal bone is divided into two parts, upper and lower, by an antero-posterior suture. In non-human vertebrates, the parietal bones typically form the rear