.Joints of the Lower Extremity. 



197 



Spina iliaca anterior inferior 



Canalis obturatorius 



Tuberculum pubicum 



Ligamentum pubicum superiua 



Lamina 

 fibrocartilaginea interpubica 



Acetabulum 



Ligamentum trans- 

 versum acetabuli 



Ligamentuni arcuatum pubis 



Membrana obturatoria 



Tuber ischiadicum 



246. Symphysis pubis and right half of pelvis 



With ligaments, from in front and below. 



(Only those fibres of the labrum glenoidale which form the ligamentum transversum acetabuli 



have been retained.) 



The membraua obturatoria is usually a thin fibre plate which almost completely 

 closes the foramen obturatum. The fibres arise from the margins of the foramen, coming in 

 the lower and posterior part from the posterior surface of the same. The direction of the 

 fibres is usually transverse. The uppermost bands stretch out below the sulcus obturatorius 

 between the tubercula obturatoria and transform this groove into the short canalis obturatorius 

 (for the a. and vv. obturatoriae ; n. obturatorius). 



In the unpaired symphysis ossium pubis (see also Fig. 247), the two pubic bones 

 are united with one another in the median plane. Between the opposing rough facies symphy- 

 seos, which are covered over with a layer of hyaline cartilage, is intercalated a fibrocartilagi- 

 nous disc (lamina fibrocartilayinea interpubica) (0. T. interpubic disc). This projects some- 

 what on the posterior surface as a narrow ridge ; in front it broadens essentially and is covered 

 by a layer of decussating fibres which are connected with the tendons of the mm. recti ab- 

 dominis. The uppermost, transverse fibre layer stretches out between the upper margins of 

 the rami superiores of the pubic bones or rather between the tubercula pubica, and is called 

 the ligamentum pubicum superius ; lateralward it is continued behind the tuberculum pubi- 

 cum as a ridge upon the pecten ossis pubis (see Fig. 243) and there gives origin to a part of 

 the m. pectineus. The sharp-angled triangular fibrous band which extends from the ramus 

 inferior of one pubic bone to that of the other on the lower margin of the symphysis and which, 

 above, is fused with the fibr< (cartilaginous disc, is called the lujamentum arcuatum pubis (0. T. 

 ligament). 



