The Hip Bone
The hip bone is actually made up of three different bones. During the first 20 years of life it is held in place by cartilage but after that period it is then connected permanently by a bone. The three bones that make up the hip is the ilium, the ischium and the pubis. The three bones meet together in a socket and that point is called the hub.
As one examines the hip bone, it appears to look like a propeller. The blades of the propeller would be the flattened wing of the ilium and the schiopubic bone. The acetabulum reserves the weight of the torso and the upper limbs which is being relayed by the sacroiliac joint. The ring that one can see while examining the hip bone is made with the meeting of the posterior and inferior ischium with the anterior and inferior pubis. The center hole of the ring is called the obturator foramen. The bone that supports and allows us to sit is the ischium, that’s why it’s significant to us, specially the ischial tuberosity.
The Pelvic Girdle
The symphysis pubis connects the two hip bones together forming the interpubic joint, which is a fibrocartilage with cartilaginous disc. The union of this two bones is what we now call the pelvic girdle. Interestingly, with respect to the world girdle, the ischiopubic bones certainly are similar to the clavicle and the iliac bones to the scapulae. The function of the pelvic girdle is inclined more towards being weight-bearing so it is less mobile compared to its pectoral counterpart. The bowl shape of the pelvic girdle houses and protects the urinary bladder, inner reproductive organ and some parts of the lower digestive tract.
Three bones combined make up the pelvis, these are the two hip bones and the sacrum. The basin or cavity of the pelvis actually has 2 parts, namely the greater and the lesser pelvis. These parts are sometimes referred to s the false and true pelvis respectively. The pelvic diaphragm makes up the floor of the pelvis and is the boundary that separates the pelvis with that of the perineum. As one can observe, the pelvis is a truly massive structure. Its strength is actually comparable to that of the cranium. It owes its massive size to the muscles and ligaments surrounding the bone.
The part of the pelvis below an oblique line from the sacral promontory, forward and downward along the arcuate lines of the ilium to be pubic crest or the floor of the pubic tubercle is what comprises the true pelvis.
Because of its complexity, the hip is vulnerable to injury. A better understanding on the principles associated with the anatomy of the hip, the pelvic girdle and the pelvis will allow you to better understand the origin of discomfort, if one exists.