THE SYMPHYSIS PUBIS 



207 



the anterior and posterior ligaments of the symi)hysis, add very materially to its 

 security. In fact, the ligament may be said to split supcriorl}- into two layers, one 

 ])assing over the front, and the other over the back of the articulation. It is 

 sometimes known as the ligannentum arcuatum. 



The interosseous fibro-cartilage varies in thickness in different sul)jects, but 

 is thicker in the female than in the male. It is thicker in front than behind, and 

 projects l)eyond tlie edges of the l)ones, especially jjosteriorly (see tig. 212), blend- 

 ing intimately witli the ligaments at its margins. It is sometimes uninterruptedly 



Fio. 212— PosTKKiou View of the Symphysis Pubis, showing the Backward Pro.jec- 



TIOX OF THE SYMPHYSIAL SUBSTANCE AND THE DECUSSATION OF THE FiBKES FROM THE 



Inferior Pubic Ligajient. 



Inferior pubic ligament 



woven throughout, but at others has an elongated narrow fissure, partially dividing 

 the cartilage into two plates, with a little fluid in the interspace (fig. 213). This 

 is situated towards the upper and posterior aspects, but does not usually reach 

 either; it generally extends aVjout half the length of the cartilage. When this cavity 

 is large, especially if it reaches or approaches very near to the circumference of the 

 cartilage (which, however, it very rarely does), it is thought by some anatomists 

 that it more nearly resembles a diarthrodial than an amphiarthrodial joint, and it 

 is then classed with the sacro-iliac joint under similar conditions, as ' diartliro- 



FiG. 213. — Section of Symphysis to show the Synovial Cavity. 



amphiarthrosis. ' The interosseous cartilage is intimately adherent to the rough 

 osseous surface of the bone, which is ridged to give it a firmer attachment; and, on 

 forcing the Ijones apart, it does not frequently split into two plates, but is torn from 

 the V>one on one side or the other. 



The arterial supply is from twigs of the internal pudic, pubic branches of the 

 obturator and epigastric, and ascending branches of the internal circumfiex and 

 superficial external })udic. 



The nerve-supply has not been satisfactorily made out. but it probably comes, 



