THE OS PUBIS 95 



Poupart's ligament. The straight head of the rectus femoris 

 arises from the anterior-inferior spine of the ilium. 



The external surface, or dorsum ilii, presents three curved 

 gluteal lines. The posterior or superior one commences 2 inches 

 in front of the posterior superior spine, and curves down and 

 forward to the back part of the iliosciatic notch. The middle 

 gluteal line begins in front about Ij inches behind the anterior 

 superior spine, and arches back and down to the upper part 

 of the notch. The inferior gluteal line, less strongly marked, 

 commences just above the anterior inferior spine, and passes 

 back to the forepart of the notch. Behind the posterior line 

 is a semilunar surface, rough above for the gluteus maximus; 

 the sickle-shaped space between the posterior and middle 

 lines and iliac crest is occupied by the gluteus medius; the 

 gluteus minimus is between the middle and inferior lines. 

 Just above the acetabulum is an elongated mark for the re- 

 flected head of the rectus femoris. 



The internal surface is divided into two unequal parts. The 

 anterosuperior part is much the larger, and is called the iliac 

 fossa, or venter ilii. It is concave and smooth, giving attach- 

 ment to the iliacus muscle, excepting at its anteroinferior 

 portion. It is separated from the true pelvis by the iliac portion 

 of the iliopectineal. 



To the inner side of the anterior inferior spine is a shallow 

 groove, the greater iliac notch, which lodges the iliopsoas muscle 

 as it passes under Poupart's ligament; the inner boundary of 

 the groove is the iliopectineal eminence, making the junction of 

 the pubis and ilium. The posteroinferior part is again divided, 

 presenting from below upward (1) a smooth curved surface 

 in the true pelvis, giving attachment in part to a portion of 

 the obturator internus, separated from the iliac fossa by the 

 iliac portion of the iliopectineal line; (2) the auricular surface, 

 for articulation with the sacrum; (3) depressions for the pos- 

 terior sacroiliac ligament; (4) a rough surface giving origin 

 to the erector and multifidus spinre muscles. 



The Os Pubis 



The os pubis forms the anterior wall of the pelvis, and bounds 

 the thyroid foramen above and partly in front. It consists 

 of a body and two rami. At the inner extremity of the body 



