Hip Bone Anatomy PDF

# Hip Bone The hip bone is located in the pelvic girdle. It is an irregular bone. It is made up of three parts: ilium, pubis, and ischium. ## Ilium The ilium is the largest of the three parts and makes up 2/5 of the hip bone. It has three borders: an upper border, an anterior border, and a poste...

# Hip Bone The hip bone is located in the pelvic girdle. It is an irregular bone. It is made up of three parts: ilium, pubis, and ischium. ## Ilium The ilium is the largest of the three parts and makes up 2/5 of the hip bone. It has three borders: an upper border, an anterior border, and a posterior border. It also has two surfaces: an outer surface, and an inner surface. ### Upper Border The upper border of the ilium is called the iliac crest. It extends between the anterior superior iliac spine and the posterior superior iliac spine. The iliac crest is S-shaped, and it contains an area between the anterior 2/3 and the posterior 1/3 that is called the intermediate area. There is also a bony prominence on the outer lip of the iliac crest called the iliac tubercle that is about 5 cm behind the anterior superior iliac spine. ### Anterior Border The anterior border begins at the anterior superior iliac spine and ends at the anterior inferior iliac spine. ### Posterior Border The posterior border begins at the posterior superior iliac spine and ends at the posterior inferior iliac spine. It forms the upper margin of the greater sciatic notch. ### Outer (Gluteal) Surface The outer surface of the ilium has three ridges called the gluteal lines: the posterior gluteal line, the middle gluteal line, and the inferior gluteal line. ### Inner (Pelvic) Surface The inner surface of the ilium has the iliac fossa, which is separated by the arcuate line. The iliac fossa is separated from the other areas by the iliac tuberosity. ### Auricular Surface The auricular surface of the ilium articulates with the sacrum at the sacroiliac joint. ## Pubis The pubis makes up 1/5 of the hip bone and consists of three parts: the body of the pubis, the superior pubic ramus, and the inferior pubic ramus. ### Body of Pubis The body of the pubis has three surfaces: the anterior surface, posterior surface, and medial surface. It articulates with the medial surface of the opposite pubis bone, forming a structure called the symphysis pubis. The upper border of the body of the pubis is called the pubic crest, and it ends laterally at a pubic tubercle. ### Superior Pubic Ramus The superior pubic ramus has three surfaces: the upper pectineal surface, the posterior pelvic surface, and the inferior obturator surface. The pectineal surface is bounded behind by the pectineal line. The posterior pelvic surface ends laterally at the ilio-pubic eminence. ### Inferior Pubic Ramus The inferior pubic ramus joins the ischial ramus, forming the ischio-pubic ramus. The ischio-pubic ramus forms the side of the pubic arch, and it has two surfaces: an outer surface and an inner surface. ## Ischium The ischium makes up the remaining 2/5 of the hip bone, and it consists of two parts: the body of the ischium and the ischial tuberosity. ### Body of Ischium The body of the ischium has two borders: an anterior border and a posterior border. The anterior border of the body of the ischium is part of the obturator foramen, while the posterior border forms the lower part of the greater sciatic notch. The body of the ischium ends below at the ischial spine, which is followed by the lesser sciatic notch. ### Ischial Tuberosity The ischial tuberosity projects from the body of the ischium and is divided by a horizontal ridge into two parts: an upper part and a lower part. The upper part is quadrangular and is divided by an oblique ridge into two areas: an upper lateral area and a lower medial area. The lower part is triangular and is divided by a vertical ridge into two parts: a medial part and a lateral part. ## Acetabulum and Obturator Foramen The acetabulum is a hollow depression on the hip bone that is directed laterally. It has a horse-shoe shaped articular area. The margin of the acetabulum is deficient inferiorly and forms a notch that is completed by a transverse acetabular ligament to form the acetabular foramen. The obturator foramen is located beneath and in front of the acetabulum. It is filled with the obturator membrane, except superiorly, where it leaves space for an obturator canal. ## Side Identification The acetabulum and the ischial tuberosity are located below and behind the rest of the hip bone.