346 THE ABDOMEN AND PELVIS 



blends with the two posterior layers of the latter so that this part of the gut 

 attains the peritoneal relationship which is found in the adult. 



The caecal outgrowth rapidly increases in length. Its proximal fourth 

 or less forms the caecum, and its distal part forms the vermiform process. 

 At birth the caecum is conical in shape and the vermiform process is attached 

 to its apex. This condition may persist the infantile ccecum but, normally, 

 the lateral wall of the caecum increases more rapidly than the medial wall, 

 and in the adult the vermiform process springs from the latter. After the 

 viscera are withdrawn from the umbilical cord (p. 288) into the abdomen, 

 the caecum lies in relation to the under surface of the liver in continuity with 

 the transverse colon. As the colon increases in length, the caecum gradually 

 descends, and at birth it lies in the right iliac fossa. Mai-descent or non- 

 descent is a well-recognised anomaly and the caecum is then frequently of the 

 infantile type. When it is not found in its normal position in abdominal 

 operations the possibility of this condition must be borne in mind. 



Prior to the descent of the caecum the vermiform process may take up 

 a retro-caecal position, and it may become fixed in this situation, losing its 

 peritoneal covering. When the caecum descends the vermiform process is 

 left behind in the extra-peritoneal retro-caecal position (Fig. 104, 7). 



Sometimes the rotation of the intestines is excessive, so that the caecum 

 is carried across the duodenum to its left side. It will then be found, together 

 with the vermiform process, between the two layers of the transverse meso- 

 colon, while the terminal part of the ileum occupies the areas in which the 

 caecum, ascending colon, and right colic flexure are normally found. 



The mesenteries of the ascending, descending, and iliac cola often persist 

 during childhood and disappear later. This accounts for the incidence of 

 intussusception, in which the whole length of the large intestine commonly 

 possesses a mesentery. More rarely, an excess of peritoneum may persist 

 in the adult, and such a persistence may explain the condition of " mobile 

 caecum " and the accompanying " Jackson's veil " (p. 329). 



The Kidneys lie, one on each side of the vertebral column, 

 opposite the twelfth thoracic, first, second, and third lumbar 

 vertebrae, but owing to the large size of the right lobe of the 

 liver the right one usually lies at a somewhat lower level than 

 the left. The kidney is about 2 inches wide and 4! inches long ; 

 and its long axis is directed from above downwards and laterally. 

 The upper pole is limited above by a horizontal plane drawn mid- 

 way between the transpyloric plane and the xiphisternal junction; 

 the lower pole extends to the subcostal plane. The transpyloric 

 plane passes through the hila of both kidneys at about i \ inches 

 from the median plane. When the position of the hilum is 

 determined on the surface it is not difficult to map out the 

 kidney with the help of the facts which have been enumerated. 



The Ureters may be indicated on the anterior abdominal 

 wall by lines drawn downwards from each hilum at a distance 

 of i inches from the median plane. These vertical lines 

 trisect the line joining the anterior-superior iliac spines at points 

 which correspond to the bifurcations of the common iliac arteries. 

 These vertical lines correspond to the abdominal parts of the 



