396 CLINICAL APPLIED ANATOMY. 



seven this anastomosis is so large as to form the origin of the 

 main portion of the obturator vessel. When this " abnormal " 

 origin of the obturator artery is present, in 10 per cent, of the 

 instances the vessel runs over the anterior or upper margin of the 

 femoral ring, and then down along its inner border to reach 

 the obturator foramen. In another 37 per cent, it passes across 

 the femoral ring, and in 53 per cent, it arrives at the obturator 

 aperture by skirting the external side of the femoral opening. 

 Thus it will be seen that if a femoral hernia becomes strangu- 

 lated, the artery will be liable to injury, if the knife be used, 

 in at least 10 per cent, of all cases where its abnormal origin 

 is present. Moreover, if the neck of the hernial sac in its 

 descent pushes the artery over, when lying across the ring, to 

 the inner side it will again become placed in a position of 

 danger. 



In the strangulation of a femoral hernia the edge of Gimber- 

 nat's ligament tends to exercise a sharp cutting pressure upon 

 the sac and its contents ; hence the very rapid damage which the 

 intestine is likely to undergo. 



When a femoral protrusion has left the femoral canal, it most 

 frequently tends to descend the front of the thigh, rather than 

 to ascend superficial to Poupart's ligament. The upward course 

 is induced probably by the attachment of the deep layer of the 

 superficial fascia to the fascia lata being very firm. 



A femoral hernia is not infrequently sacculated by the pressure 

 of fibrous bands derived from the cribriform fascia. 



Umbilical Hernia. During the process of development the 

 two lateral halves of the parietes of the abdomen approach one 

 another and ultimately coalesce, save for the aperture through 

 which pass the umbilical vessels. This opening is closed by 

 scar-tissue subsequent to the separation of the cord. 



The anatomy of the umbilicus in the first few weeks after 

 birth shows an arrangement of fibres of semi-elastic tissue in 

 the form of a sphincter. These tend to become less elastic and 

 more fibrous, so that they gradually contract, and, as it were, 

 cut through the structures which originally traversed the 



