THE BONES OF THE LOWER LIMB 225 



in the latter situation it gives origin to the gemellus inferior. The 

 inner border is prominent and sharp, and gives attachment to the 

 great sacro-sciatic ligament. The outer border gives origin to the 

 quadratus femoris. The anterior border is sharp and prominent, 

 and forms the lower part of the posterior margin of the obturator 

 foramen. The siu'faces are postero-inferior, external, and internal. 

 The postero-inferior surface lies between the outer and inner borders, 

 and is di^^ded into two parts. The posterior portion is somewhat 

 quadrilateral, and is subdi\'ided into two parts by a diagonal line 

 directed downwards, forwards, and outwards. The upper and outer 

 part gives origin to the semimembranosus, and the lower and inner, to 

 the conjoined long head of the biceps and semitendinosus. The 

 inferior portion, which is in line with the inner margin of the ramus, 

 is rough and triangular, and gives origin to fibres of the adductor 

 magnus. The external surface is situated between the outer and 

 anterior borders, and supports the obtiu-ator externus. The 

 internal surface is placed between the inner and anterior borders. 

 It looks towards the ischio-rectal fossa, and gives origin to fibres 

 of the obtiu^ator intemus. 



The ramus is the compressed portion which extends upwards 

 and inwards, from the tuberosity, on the anterior aspect of the 

 obturator foramen, where it joins the inferior pubic ramus, the 



?lace of meeting being indicated externally by a rough ridge, 

 he outer border is sharp for a portion of the obturator membrane, 

 and forms part of the anterior margin of the obturator foramen. 

 The inner border is thick, and anteriorly it is rough and everted, 

 more so in the male than in the female, for the attachment 

 of the fascia of Colles, cms penis, and ischio-cavemosxis muscle. 

 In the female this part gives attachment to the crus cUtoridis and 

 erector clitoridis. Elsewhere the inner border gives attachment 

 to the triangular ligament and compressor urethrae. The outer 

 surface gives origin, from within outwards, to portions of the 

 adductor magnus and obturator externus. The inner or pelvic 

 surface gives attachment to part of the obturator intemus and 

 parietal pelvic fascia. At its lower part, near the inner border, 

 there is a sharp ridge which gives attachment to the falciform 

 process of the great sacro-sciatic ligament. 



The OS pubis lies in the anterior wall of the pelvis, and is 

 composed of a body and two rami, superior and inferior. The 

 body is compressed from before backwards, and occupies an 

 oblique plane, which is directed downwards and backwards. It 

 presents three surfaces — anterior, posterior, and internal. The 

 anterior or femoral surface has an inclination downwards. At its 

 upper and inner part, below and external to the pubic angle, it gives 

 origin to the adductor longus, and, lower dowTi, to the following 

 muscles, in order from within outwards — ^gracilis, adductor brevis, 

 a small portion of the adductor magnus, and obturator externus. 

 The posterior or pelvic surface has an inclination upwards, and 

 gives attachment from without inwards to the obturator intemus, 



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