ACETABULUM OBTURATOR FORAMEN. 87 



the pectineal line is a smooth depression, which supports the femoral 

 vein, and a little more externally an elevated prominence, the pec- 

 tineal eminence, which divides the surface for the vein from another 

 depression which overhangs the acetabulum, and lodges the psoas 

 and iliacus muscles. The inferior border is broad and deeply 

 grooved, for the. passage of the\ obturator vessels and nerve; and 

 sharp upon the side of the ramus, to form part of the boundary of 

 the obturator foramen. The symphysis is the inner extremity of the 

 body of the bone ; it is oval and rough, for the attachment of a liga- 

 mentous structure analogous to the intervertebral substance. The 

 ramus of the pubis descends, and is continuous with the ramus of 

 the ischium. . Its inner border is considerably everted, to afford a 

 strong attachment to the crus penis. 



The acetabulum is a deep cup-shaped cavity, situated at the point 

 of union between the ilium, ischium, and pubis ; a little less than 

 two-fifths being formed by the ilium, a little more than two-fifths 

 by the ischium, and the remaining fifth by the pubis. It is bounded 

 by a deep rim or lip, which is broad and strong above, where most 

 resistance is required, and marked in front by a deep notch, which 

 transmits the nutrient vessels into the joint. At the bottom of the 

 cup, and communicating with the notch, is a deep and circular pit, 

 which lodges a mass of fat, and gives attachment to the broad ex- 

 tremity of the ligamentum teres. 



The obturator or thyroid for amen is a large oval interval between the 

 ischium and pubis, bounded by a narrow rough margin, to which a 

 ligamentous membrane is attached. The upper part of the foramen 

 is increased in depth by the groove in the under surface of the os 

 pubis, which lodges the obturator vessels and nerve. 



Developement. By e/g7/tcentres ; three principal one for the ilium, 

 one for the ischium, and one for the pubis ; and five secondary one 

 for the crest of the ilium, and one for its anterior inferior spinous 

 process, one for the centre of the acetabulum, one for the tuberosity 

 of the ischium, and one (not constant) for the angle of the pubis. 



Articulations. With three bones ; sacrum, opposite innominatum, 

 and femur. 



Attachment of Muscles and Ligaments. To thirty-five muscles; to 

 the ilium, thirteen ; by the outer lip of the crest, to the obliquus ex- 

 ternus for two thirds, and to the latissimus dorsi for one-third its 

 length, and to .the tensor vaginae femoris by its anterior -fourth ; by 

 the middle of the crest, to the internal oblique for three-fourths its 

 length, by the remaining fourth to the erector spinae ; by the inter- 

 nal lip, to the transversalis for three-fourths, and to the quadratus 

 lumborum by the posterior part of its middle third. By the external 

 surface, to the gluteus medius, minimus and maximus, and to one 

 head of the rectus ; by the internal surface, to the iliacus ; and by 

 the anterior border, to the sartorius, and the other head of the rectus. 

 To the ischium sixteen ; by its external surface, the adductor magnus 

 and obturator externus'; by the internal surface, the obturator internus 

 and levator ani ; by the spine, the gemellus superior, levator ani, 



