234 OSTEOLOGY 



between the anterior and inferior gluteal lines is concave from above downward, 

 convex from before backward, and gives origin to the Glutseus minimus. Between 

 the inferior gluteal line and the upper part of the acetabulum is a rough, shallow 

 groove, from which the reflected tendon of the Rectus femoris arises. 



The internal surface (Fig. 236) of the ala is bounded above by the crest, below, 

 by the arcuate line; in front and behind, by the anterior and posterior borders. 

 It presents a large, smooth, concave surface, called the iliac fossa, which gives 

 origin to the Iliacus and is perforated at its inner part by a nutrient canal; and 

 below this a smooth, rounded border, the arcuate line, which runs downward, for- 

 ward, and medialward. Behind the iliac fossa is a rough surface, divided into two 

 portions, an anterior and a posterior. The anterior surface (auricular surface}, 

 so called from its resemblance in shape to the ear, is coated with cartilage in the 

 fresh state, and articulates with a similar surface on the side of the sacrum. 

 The posterior portion, known as the iliac tuberosity, is elevated and rough, for 

 the attachment of the posterior sacroiliac ligaments and for the origins of the 

 Sacrospinalis and Multifidus. Below and in front of the auricular surface is the 

 preauricular sulcus, more commonly present and better marked in the female 

 than in the male; to it is attached the pelvic portion of the anterior sacroiliac 

 ligament. 



The crest of the ilium is convex in its general outline but is sinuously curved, 

 being concave inward in front, concave outward behind. It is thinner at the center 

 than at the extremities, and ends in the anterior and posterior superior iliac spines. 

 The surface of the crest is broad, and divided into external and internal lips, 

 and an intermediate line. About 5 cm. behind the anterior superior iliac spine 

 there is a prominent tubercle on the outer lip. To the external lip are attached 

 the Tensor fasciae latse, Obliquus externus abdominis, and Latissimus dorsi, and 

 along its whole length the fascia lata ; to the intermediate line the Obliquus internus 

 abdominis; to the internal lip, the fascia iliaca, the Transversus abdominis, 

 Quadratus lumborum, Sacrospinalis, and Iliacus. 



The anterior border of the ala is concave. It presents two projections, separated 

 by a notch. Of these, the uppermost, situated at the junction of the crest and 

 anterior border, is called the anterior superior iliac spine; its outer border gives 

 attachment to the fascia lata, and the Tensor fasciae latse, its inner border, to the 

 Iliacus; while its extremity affords attachment to the inguinal ligament and gives 

 origin to the Sartorius. Beneath this eminence is a notch from which the Sartorius 

 takes origin and across which the lateral femoral cutaneous nerve passes. Below 

 the notch is the anterior inferior iliac spine, which ends in the upper lip of the 

 acetabulum; it gives attachment to the straight tendon of the Rectus femoris and 

 to the iliofemoral ligament of the hip-joint. Medial to the anterior inferior spine 

 is a broad, shallow groove, over which the Iliacus and Psoas major pass. This 

 groove is bounded medially by an eminence, the iliopectineal eminence, which 

 marks the point of union of the ilium and pubis. 



The posterior border of the ala, shorter than the anterior, also presents two 

 projections separated by a notch, the posterior superior iliac spine and the posterior 

 inferior iliac spine. The former serves for the attachment of the oblique portion 

 of the posterior sacroiliac ligaments and the Multifidus; the latter corresponds 

 with the posterior extremity of the auricular surface. Below the posterior inferior 

 spine is a deep notch, the greater sciatic notch. 



The Ischium (os ischii). The ischium forms the lower and back part of the 

 hip bone. It is divisible into three portions a body and two rami. 



The Body (corpus oss. ischii). The body enters into and constitutes a little 

 more than two-fifths of the acetabulum. Its external surface forms part of the 

 lunate surface of the acetabulum and a portion of the acetabular fossa. Its internal 

 surface is part of the wall of the lesser pelvis; it gives origin to some fibers of the 



