174 THE SKELETON. 



part of the acetabulum, is a roughened surface (sometimes a depression), to which 

 is attached the reflected tendon of the Rectus femoris muscle. 



The Internal Surface (Fig. 121) of the ilium is bounded above by the crest ; 

 below it is continuous with the pelvic surface of the os pubis and ischium, a faint 

 line only indicating the place of union ; and before and behind it is bounded by 

 the anterior and posterior borders. It presents a large, smooth, concave surface, 

 called the iliac fossa, or venter ilii, which lodges the Iliacus muscle, and presents 

 at its lower part the orifice of a nutrient canal ; and below this a smooth, rounded 

 border (the linea ilio-pectinea), which separates the iliac fossa from that portion of 

 the internal surface which enters into the formation of the true pelvis, and which 

 gives attachment to part of the Obturator interims muscle. Behind the iliac fossa 

 is a rough surface divided into two portions, an anterior and a posterior. The 

 anterior or auricular surface, so called from its resemblance in shape to the ear, is 

 coated with cartilage in the recent state, and articulates with a surface of similar 

 shape on the side of the sacrum. The posterior portion is rough, for the attach- 

 ment of the posterior sacro-iliac ligaments and for a part of the origin of the 

 Erector and Multifidus spinre. 



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

 being concave inward in front, concave outward behind. It is longer in the female 

 than in the male, very thick behind, and thinner at the centre than at the extremi- 

 ties. It terminates at either end in a prominent eminence, the anterior superior 

 and posterior superior spinous process. The surface of the crest is broad, and 

 divided into an external lip, an internal lip, and an intermediate space. About two 

 inches behind the anterior superior spinous process there is a prominent tubercle 

 on the outer lip. To the external lip is attached the Tensor fasciae femoris, 

 Obliquus externus abdominis, and Latissimus dorsi, and along its whole length, 

 the fascia lata ; to the space between the lips, the Internal oblique ; to the internal 

 lip, the Transversalis, Quadratus lumborum, and Erector spinae, the Iliacus, and 

 the fascia iliaca. 



The anterior border of the ilium 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 spinous process of the ilium, 

 the outer border of which gives attachment to the fascia lata and the origin of 

 the Tensor fasciae femoris ; its inner border, to the Iliacus ; while its extremity 

 affords attachment to Poupart's ligament and the origin of the Sartorius. Beneath 

 this eminence is a notch which gives attachment to the Sartorius muscle, and 

 across which passes the external cutaneous nerve. Below the notch is the anterior 

 inferior spinous process, which terminates in the upper lip of the acetabulum ; it 

 gives attachment to the straight tendon of the Rectus femoris muscle and the 

 ilio-femoral ligament. On the inner side of the anterior inferior spinous process 

 is a broad, shallow groove, over which passes the Ilio-psoas muscle. This groove is 

 bounded internally by an eminence, the ilio-pectineal, which marks the point of 

 union of the ilium and os pubis. 



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

 projections separated by a notch, the posterior superior and the posterior inferior 

 spinous processes. The former corresponds with that portion of the inner surface 

 of the ilium which serves for the attachment of the oblique portion of the sacro- 

 iliac ligaments and the Multifidus spinae ; the latter, to the auricular portion which 

 articulates with the sacrum. Below the posterior inferior spinous process is a deep 

 notch, the great sacro-sciatic. 



The Ischium forms the lower and back part of the os innominatum. It is 

 divisible into a thick and solid portion the body ; a large, rough eminence, on 

 which the trunk rests in sitting the tuberosity ; and a thin part which passes 

 forward and slightly upward the ramus. 



The body, somewhat triangular in form, presents three surfaces, external, 

 internal, and posterior ; and three borders, external, internal, and posterior. The 

 external surface corresponds to that portion of the acetabulum formed by the 



