148 Anatomy & Physiology Essentials Copyright Goodheart-Willcox Co., Inc. The pubis is the anterior (front) portion of each coxal bone. The inferior pubic ramus is fused to the ischial ramus to enclose the obturator foramen, a large opening for blood vessels and nerves traversing to the anterior thigh. The two pubic bones fuse in the center front of the body at the pubic symphysis, where the bones are joined by a disc of hyaline cartilage. The ilium, ischium, and pubis fuse to form the lateral and slightly anterior facing acetabulum (as-eh-TAB-yoo-lum). This is a deep, bony socket that receives the head of the thigh bone. The hip is an extremely stable joint thanks to the depth of the acetabulum and the strength of the large muscles surrounding the hip. the weight of the upper body during sitting. The ischium has several features: • The greater sciatic notch is a prominent feature on the posterior hip at the junction of the ilium and ischium. • The ischial spine is a projection inferior to the greater sciatic notch that narrows the passageway through which babies pass during birth. • The ischial tuberosity is a raised area that directly supports upper body weight during sitting. • The ischial ramus is the narrow bony connection between the ischium and the pubis. Iliac crest Anterior superior iliac spine Anterior inferior iliac spine Pubis Inferior pubic ramus Ischial spine Greater sciatic notch Ischial tuberosity Anterior view Lateral view Coxal bone Ischium Acetabulum Ilium Sacroiliac joint Obturator foramen Coccyx Sacrum Pubic symphysis Ischial spine Acetabulum Iliac crest Ilium Pubis Ischium Body of pubis Obturator foramen Ischial ramus Posterior inferior iliac spine Posterior superior iliac spine Ala © Body Scientific International Figure 5.27 Bones of the pelvis.