172 SURGICAL ANATOMY OF 



the case, however, of the incision through the parietes 

 made for the application of ligatures to the iliac arte- 

 ries, the abdominal muscles are divided, whilst the peri- 

 toneum is kept entire. The resilience of the walls of 

 this region allows of the ready manipulation of its con- 

 tents, with a view to diagnosis. Penetrating wounds 

 are frequently followed by hernial protrusion, on ac- 

 count of the laxity of their cicatrices. 



In the linea alba, between the two recti, is the um- 

 bilicus, the cicatrix of a foetal structure, the umbilical 

 cord, which having been cut or tied at birth, has 

 shrunk up to its attachment at the abdominal parietes, 

 and the closure of the opening is formed by tough 

 fibrous tissue, closely adherent to the peritoneum and 

 neighboring tissues. 



Umbilical hernice, if formed at an early period, pos- 

 sess a very thin covering of peritoneum, as that mem- 

 brane is but recently formed at that spot, and in almost 

 all cases this sac contains omentum, transverse colon, or 

 small intestine. 



Umbilical hernia is almost always a congenital affec- 

 tion ; ventral hernia, though occurring at this spot, is 

 really a protrusion through a preternatural opening in 

 the fibrous coverings close to the umbilicus. 



The regions of the abdominal parietes of greatest 

 interest to the surgeon, and which demand a more accu- 

 rate anatomical description, are those connected with 

 inguinal and crural hernia; and though these protru- 

 sions are formed of structures contained in the abdomi- 

 nal cavity, they would be best considered in the rela- 

 tions in which they would present themselves namely, 

 from the surface. 



