240 



THE ARTICULATIONS 



Both on the front and back aspects of the joint it gives off decussating fibres, which, by their 

 interlacement over the anterior and posterior ligaments of the symphysis, add very materi- 

 ally to its secm-ity. In fact, the ligament may be said to split superiorly into two layers, one 

 passing over the front, and the other over the back, of the articulation. 



The interpubic fibro -cartilage varies in thickness in different subjects, but 

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

 and projects bej'ond the edges of the bones, especially posteriorly (see fig. 277), 

 blending intimately with the ligaments at its margins. It is sometimes uninter- 

 ruptedly woven throughout, but at others has an elongated narrow fissure, 

 partially dividing the cartilage into two plates, mth a little fluid in the interspace 



Fig. 277.- 



-PosTERiOR View of the Symphysis Pubis, showing the Decussation of the 

 Fibres from the Arcuate Ligament. 



Arcuate ligament 



(fig. 278). This is situated toward the upper and posterior aspects, but does 

 not usually reach either; it generally extends about half the length of the 

 cartilage. 



When this cavity is large, especially if it reaches or approaches very near to the circumfer- 

 ence 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 'diarthroamphiarthrosis.' The interos- 

 seous cartilage is intimately adherent to the layer of hyaline cartilage which covers the medial 

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

 forcing the bones apart, it does not frequently spUt into two plates, but is torn from the bone 

 on one side or the other. 



Fig. 278. — Section of Symphysis to show the Synovial Cavity. 



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

 of the obturator and epigastric, and ascending branches of the internal circumflex and super- 

 ficial e.Ktornal jjudic. 



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

 from the inttsriial ijudic and in part from the ilio-hypogastric and ilio-inguinal. 



The movements amount only to a .slight yielding of the cartilage; neither muscular force 

 nor extrin.sic forces produce any a[)prccial)Ic movement in the ordinary condition. Occasion- 

 ally, as the result of child-bearing, the joint becomes unnaturally loose, and then walking and 

 standing are painfully unsteady. It is known that, during pregnancy and parturition, the 



