THE ORGANS OF THE ABDOMEN 



73 



four inches long and two and a-half broad, and weighing about 

 four ounces each. They are situated at the back of the abdomen, 

 one on each side of the vertebral column, deeply seated in the 

 flesh of the loins on a level with the upper lumbar vertebra. 

 These are the organs which 

 we find imbedded in the 

 flesh and fat of the ' loin of 

 mucton.' The use of the 

 kidneys is to separate cer- 

 tain poisonous substances 

 which have accumulated in 

 the blood during its circu- 

 lation throughout the body. 

 These impurities are con- 

 veyed away from the kidneys 

 by two tubes called ureters, 

 which communicate with 

 the bladder. 



The bladder is a very 

 strong membranous and 

 muscular bag which lies in 

 the cavity of the pelvis. 

 This organ serves to con- 

 tain' the fluid (the urine) 

 which is being constantly 

 excreted by the kidneys, 

 thus enabling it to be dis- 

 charged at intervals. 



Most of the organs of the 

 abdomen are surrounded 

 and supported by a mem- 

 brane called the perito- 

 neum (Gr. peri, about ; and 

 tetnOy I stretch). This is a 

 double membrane forming 

 a shut sac, resembling the 

 corresponding membranes 

 (the pleurae and pericar- 

 dium) of the thorax. Its outer layer lines the inner surface of 

 the abdomen, and the other layer is reflected round the various 

 organs, forming their exterior coverings. Some of the folds of the 

 peritoneum connect portions of the intestines with the posterior 

 walls of the abdomen. These are called the mesenteries (Gr. 

 mesos, middle ; and enteron^ the intestine). 



Fig. 80. The Abdominal Portion of the 

 Alimentary Canal. 



c, cardiac opening of the stomach ; p, pylorus ; 

 D, duodenum : J, jejunum ; I, ileum ; cc, caecum ; 

 AC, ascending colon ; TC, transverse colon ; DC, 

 descending colon ; R, rectum. 



