6i8 ABDOMEN 



forwards, the symphysis and the promontory are approximated, 

 and, in consequence, the tension of the sacro-tuberous and 

 sacro-spinous ligaments is increased. 



Symphysis Ossium Pubis (O.T. Symphysis Pubis). This is 

 an example of a synchondrosis. In addition to the interven- 

 ing disc of fibre-cartilage which connects the cartilage-covered 

 opposing surfaces of the two pubic bones, four ligaments are 

 present, viz. : 



i. Anterior pubic. 2. Posterior pubic. 3. Superior pubic. 4. Arcuate. 



Ligamentum Pubicum Anterius. The anterior pubic ligament 

 is strongly marked, and consists of two layers of fibres a 

 superficial and a deep. The superficial fibres are oblique, and 

 cross each other like the limbs of the letter X, mingling 

 with the decussating fibres of the superior crura of the 

 subcutaneous inguinal ring. The deep fibres are transverse, 

 and extend across from one bone to the other. 



Ligamentum Pubicum Posterius. The posterior pubic liga- 

 ment consists of a very few transverse fibres on the posterior 

 aspect of the joint. 



Ligamentum Pubicum Superius. The superior pubic ligament, 

 like the preceding, is weak. It is placed upon the upper 

 aspect of the symphysis, and stretches between the crests of 

 the two pubic bones. 



Ligamentum Arcuatum Pubis (O.T. Sub-pubic Ligament}. 

 The arcuate pubic ligament is situated on the lower aspect of 

 the joint, rounds off the apex of the pubic arch. It is a 

 strong band, somewhat triangular in shape, which is attached 

 on each side to the inferior ramus of the pubic bone, and 

 above, to the fibro- cartilaginous disc. Between the crescentic 

 lower margin of this ligament and the upper border of the 

 uro-genital diaphragm there is an oval aperture through 

 which the dorsal vein of the penis passes backwards. 



Dissection. The saw should now be used, and a portion sliced off from 

 the front of the joint. The intervening plate of fibro-cartilage can in this 

 way be studied. It will be seen to be thicker and denser in front than 

 behind. As a general rule, a small synovial cavity will be found towards 

 its back part, and nearer its upper than its lower end. 



Membrana Obturatoria (O.T. Thyroid Membrane). The 



obturator membrane stretches across the obturator foramen. 

 It is attached to the circumference of the foramen, except at 

 its upper part, where it bridges across the groove on the 

 under surface of the superior ramus of the pubic bone, and 



