HERNIA 261 



tissue closely connected with the superjacent skin. The 

 umbilicus marks the position where, during a large part of 

 intra-uterine life, the peritoneal cavity was prolonged through 

 the abdominal wall into the root of the umbilical cord, which 

 attached the foetus to the mother. For a considerable time 

 a portion of the gut lies in the extra-abdominal sac in the 

 root of the umbilical cord, but, before birth, it is withdrawn 

 into the abdomen and the sac shrinks and disappears. If a 

 remnant of the sac persists in the substance of the abdominal 

 wall, after birth, the wall is weakened and a portion of the 

 abdominal contents may be forced into the diverticulum, 

 causing its distension and producing an umbilical hernia. 

 The anatomical coverings from within outwards would be 

 (i) peritoneum, (2) aponeuroses of the abdominal wall equiva- 

 lent to the stretched linea alba, (3) superficial fascia, (4) skin. 

 If the foetal condition persists until birth a portion of the 

 gut lies in the umbilical cord, separating the three vessels ; 

 and more than one case has occurred in which the bowel 

 has been cut when the cord was divided after the birth of 

 the child. 



ABDOMINAL CAVITY., 



When the dissector has completed his examination of 

 the regions where hernia most commonly occurs he should 

 proceed to study the abdominal cavity and its contents. 



Dissection. The lower half of the abdominal wall has already jj 

 been divided along the median plane; now carry an incision V 6 



upwards, from the umbilicus to the xiphoid process of the^^^i/*^ 1 

 sternum, immediately to the left of the median plane, and * 

 throw the two flaps thus formed upwards and laterally over 

 the lower margins of the thorax. The abdomen will then be 

 fully opened up and the examination of its contents may com- 

 mence. As the flap on the right side is turned upwards a 

 strong fibrous cord will be noticed extending from the umbilicus 

 to the inferior surface of the liver. It is the ligamentum teres 

 of the liver and is the remains of the umbilical vein of the foetus. 

 As it ascends towards the liver, it recedes from the posterior 

 surface of the anterior abdominal wall, taking with it a fold 

 of peritoneum termed the falciform ligament of the liver. 



Shape and Boundaries of the Abdominal Cavity. The 

 abdominal cavity is ovoid in shape, and its vertical dia- 

 meter is the longest. Superiorly, it is roofed by the dome- 



