The hip bone is made up of the ilium, ischium, and pubis fused together [Fig. 7.7]. It has the ap-pearance of a two-bladed propeller with a large blade—the ilium—directed upwards, and a smaller blade, made up of the pubis and ischium, directed downwards. The two blades are almost at right an-gles to one another and meet at a narrow, thick hub where the head of the femur articulates in the acetabulum. Inferiorly, the pubis lies anterome-dially and the ischium lies posterolaterally, with a large aperture—the obturator foramen—be-tween them. The pubis and ischium are fused at the ischiopubic rami and at the acetabulum. The ischiopubic rami is a bar of bone formed inferi-or to the obturatinferi-or finferi-oramen by the union of the inferior ramus of the pubis and the ramus of the ischium.
The bodies of the two pubic bones articulate with each other at the lowest part of the anterior
Iliac crest
Iliac fossa
Anterior superior iliac spine
Anterior inferior iliac spine
Arcuate line
lliopubic eminence
Superior pubic ramus Pecten pubis Pubic tubercle
Pubic crest
Symphyseal surface Inferior pubic ramus
Greater sciatic notch
Obturator groove
Ischial spine Lesser sciatic notch
Ischial tuberosity, falciform margin
Ischial ramus Obturator foramen
Iliac tuberosity
Posterior superior iliac spine
Auricular area for sacrum Posterior inferior iliac spine
Fig. 7.7 Right hip bone seen from the medial side.
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Bones of the abdomen and pelvis
forms the smooth, concave iliac fossa. The iliac fossa lies superiorly and forms the bony wall of the greater pelvis. (2) Posterior to the iliac fossa is the sacral surface, consisting of the auricular surface and tuberosity of the ilium. (The auricular surface articulates with the sacrum.) (3) The part of the ilium medial to the acetabulum forms the superior part of the lateral wall of the lesser pelvis. A thick, curved ridge of bone—the arcuate line of the ilium—separates the parts forming the greater and lesser pelvis. The arcuate line crosses the ilium from the antero-inferior part of the auricular surface to the lateral end of the pecten pubis. This strong part of the ilium transmits compression forces from the vertebral column and the auricular surface of the ilium to the acetabulum and lower limb. The pu-bic crest, pecten pubis, arcuate line of the ilium, and promontory of the sacrum together form the superior aperture of the (lesser) pelvis—also called the linea terminalis of the pelvis. The internal surfaces of the ilium, pubis, and ischium contribute to the bony wall of the lesser pelvis. The anterosuperior margin of the obturator foramen is notched to form the obturator sulcus or obtu-rator groove. The obtuobtu-rator foramen is covered by the obturator membrane—a fibrous sheet at-tached to the sharp margin of the foramen, except at the obturator sulcus. The obturator membrane bridges the sulcus and transforms it into the obtu-rator canal which transmits the obtuobtu-rator vessels and nerve.
It is important to understand the orientation of the hip bone. The symphyseal surface of the pubic bones lies in the sagittal plane. The pubic tubercle and anterior superior iliac spine lie in the same cor-onal plane. The linea terminalis of the pelvis lies at an angle of approximately 70° to the horizontal, entirely superior to the pubic symphysis, with the sacral promontory at the level of the anterior su-perior iliac spines. As such, the susu-perior aperture of the pelvis faces the lower part of the anterior abdominal wall. The upper border of the ischial tu-berosities and the tip of the coccyx lie in the same horizontal plane. The inferior aperture of the pelvis is formed by the pubic arch, the ischial tu-berosities, the coccyx, and the sacrotuberous liga-ments. It is approximately horizontal and is filled by the perineum. In the median plane, the pubic symphysis forms the short antero-inferior wall of the lesser pelvis, and the sacrum and coccyx form the long posterosuperior wall.
muscle of the anterior abdominal wall—the ex-ternal oblique. Deep fibres of the inguinal liga-ment pass posteriorly to the pecten pubis as the lacunar ligament. These fibres continue along the superior pubic ramus as the pectineal liga-ment.
The two inferior rami of the pubic bones diverge from the subpubic angle. They form the pubic arch together with the rami of the ischia. In the anatomical position, the pubic arch lies horizon-tally and is palpable between the anterior part of the perineum (the urogenital triangle) medially and the thighs laterally. The ramus of the ischium expands posteriorly into the ischial tuberosity.
The ischial tuberosity gives attachment to the ham-string muscles of the thigh and the sacrotuberous ligament. Superior to the ischial tuberosity is a shal-low depression—the lesser sciatic notch. Further superiorly, the ischial spine projects posteromedi-ally from the ischium and separates the lesser sci-atic notch of the ischium from the greater scisci-atic notch on the posterior margin of the ilium. When the hip bone and sacrum are articulated together, the two notches form the lateral margin of a deep concavity between the bones. This space is convert-ed into two foramina—the greater and lesser sciatic foramina—by the sacrospinous and sacrotuber-ous ligaments. The sacrospinsacrotuber-ous ligament passes from the sacrum to the ischial spine. The sacrotu-berous ligament passes from the sacrum to the ischi-al tuberosity. The greater sciatic foramen leads from the lesser pelvis into the gluteal region, and the less-er sciatic foramen leads from the gluteal region into the perineum [see Figs. 15.4, 15.5].
The ilium is a flat, fan-shaped bone which extends superiorly from the acetabulum. The sup-erior margin of the ilium forms the sinuous iliac crest at the lower margin of the waist. On yourself, follow the iliac crest forwards and backwards. Ante-riorly, it slopes downwards and slightly medially to the anterior superior iliac spine. Posteriorly, it turns backwards and downwards to the posterior superior iliac spine. The posterior superior iliac spine lies at the bottom of the dimple at the level of the second sacral spine. Anterior and poste-rior infeposte-rior iliac spines lie on the margins of the ilium, inferior to the corresponding superior spines. The posterior inferior iliac spine lies at the level of the third sacral spine [Fig. 7.7].
The medial aspect of the ilium has three distinct surfaces. (1) The greater part of the medial aspect
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by the spermatic cord in the male. Immediately superolateral to the tubercle is the superficial inguinal ring—an aperture in the aponeurosis of the external oblique muscle of the abdomen. The spermatic cord descends to the scrotum in front of the pubis through the superficial inguinal ring [Fig. 8.2]. In the female, the round ligament of the uterus descends to the labium majus through the superficial inguinal ring. The margins of the ring are easily felt in the male. Place the tip of your little finger on the loose skin of the upper part of the scrotum in front of the pubis and spermatic cord and invaginate the skin upwards along the line of the cord. Where the cord disappears through the ring, the sharp margins of the superficial inguinal ring can be felt by pressing posteriorly. Pick up the spermatic cord in the scrotum between the finger and thumb. Note the firm, cord-like vas deferens buried in its posterior part. This is the duct of the testis. The ring is smaller in the female and more difficult to feel because of the amount of subcuta-neous fat in this region.
Note the slight median groove on the anterior