DISSECTION OF THE PELVIS. 351 



supported by the following muscles : the deep gluteus above, the 

 obturator externus below, the rectus femoris and the rectus parvus in 

 front, and the gemelli behind. The ligament should be incised to show 

 the synovial membrane, after which it may be removed entirely. 



The Synovial Membrane forms a complete internal lining to the 

 capsular ligament, and also invests the pubio-femoral and round liga- 

 ments in the interior of the joint. 



The Cotyloid Ligament is a ring of fibro-cartilage fixed at the margin 

 of the cotyloid cavity, which it serves to deepen for the reception of the 

 femoral head. On the inner side of the joint, where the notch interrupts 

 the rim of the cotyloid cavity, the ligament bridges over the gap, and to 

 this portion of the ring the term transverse ligament is sometimes applied. 

 This portion of the ligament thus converts the notch into a foramen, 

 through which the pubio-femoral ligament enters the joint. 



The Pubio-Femoral Ligament. This ligament derives its fibres 

 from the prepubic tendon of the abdominal muscles, the right and 

 left ligaments intercrossing their fibres in front of the pubes. It is 

 directed outwards and backwards, resting in a groove on the inferior 

 surface of the pubis, and perforating the origin of the pectineus muscle. 

 At the notch on the inner side of the cotyloid ligament, it enters the 

 hip-joint by passing above (in the natural position) the so-called 

 transverse ligament, and it terminates in the depression on the head of 

 the femur. The ligament, being attached across the middle in front, is 

 put upon the stretch when the limb is abducted, and therefore restricts 

 that movement. 



The Round Ligament (interarticular ligament or ligamentum teres). 

 This short and strong ligament is fixed above to the non-articular 

 depression at the bottom of the cotyloid cavity, and below to the excava- 

 tion on the head of the femur, being confounded at the latter point with 

 the pubio-femoral ligament. It w T ill be best displayed by cutting the 

 transverse ligament and abducting the femur. 



Direction. — It is convenient to dissect at this stage the sacro-sciatic 

 ligament, as it is necessary to remove it in order to display the pelvic 

 contents. Along with it, there will be described two other ligaments — 

 the superior and inferior ilio-sacral ligaments. 



The Sacro-sciatic Ligament (Plate 16 and Fig. 54). This is a large 

 membranous ligament which forms the greater part of the lateral 

 boundary of the pelvis. It is irregularly four-sided in form. Its upper 

 edge, which is pierced by the ischiatic artery, is fixed to the lateral lip 

 of the sacrum, and to the rudimentary transverse processes of the first 

 one or two coccygeal bones ; its lower edge is attached to the superior 

 ischiatic spine and to the tuber ischii, and between these points it forms 

 the upper boundary of the small sacro-sciatic foramen ; its anterior edge 

 is short, and forms the posterior boundary of the great sacro-sciatic 



