SYMPHYSIS PUBIS. 547 



the abdomen ; but the deeper fibres are transverse between the surfaces 

 of the bones. Some of the deepest fibres contain cartilage cells. 



There is not any strong posterior band ; but beneath the periosteum are 

 a few scattered fibres in contact with the articular cartilage. 



The superior ligamentous fibres fill the interval between the bones 

 above the cartilage. 



The subpubic ligament (fig. 191, d) (ligam. arcuatum) is a strong tri- 

 angularly-shaped band below the symphysis, and occupies the upper part 

 of the pubic arch. The apex of the ligament touches the articular carti- 

 lage, and the base, contained within the triangular perinaeal ligament, is 

 turned towards the membranous part of the urethra. 



Dissection. The cartilage will be best seen by a transverse section of 

 the pubes, which will show the disposition of the anterior ligament of the 

 articulation, and the thickness of the cartilage, with its toothed mode of 

 insertion into the bone ; but when opportunity offers, a vertical section 

 may be made. 



Cartilage (fig. 191, c). The cartilage is firmly fixed to the ridged bony 

 surfaces of the symphysis : it is wider above than below, and is generally 

 as thick again before as behind. Variations in its size depend on the 

 shape of the bones. 



Towards the posterior part of the cartilage there is a narrow fissure 

 with uneven walls ; and a fibrous structure with large interspersed com- 

 pound cells is to be recognized in the wall. It extends usually the whole 

 depth of the cartilage and through a half or a third of the thickness : it 

 is said to increase in pregnancy. In some bodies it reaches through the 

 cartilage so as to divide this into two collateral pieces. 



Movement. As the bones are not in contact in the pubic symphysis, but 

 are united by an intermediate cartilage, the motion is usually very slight. 

 The kind of movement of the hip bone is inward and outward, so as to 

 increase or diminish the pelvic cavity. 



When the pubic cartilage is divided into two by a larger central space 

 than usual, greater freedom of motion is present in the symphysis ; and 

 in pregnancy the looseness of the innominate bone is sometimes so great 

 as to interfere seriously with locomotion. 



