222 OUTLINES OF EQUINE ANATOMY. 



Avhicli serve to strengthen it. It is transparent and 

 through it we see the caecum and colon, with their longitu- 

 dinal muscular bands and resulting puckerings. 



The abdominal cavity is bounded anteriorly by the 

 diaphragm, inferiorly and laterally by the abdominal 

 muscles, superiorly by the ]3S08e muscles attached under- 

 neath the lumbar vertebrae, posteriorly by the pelvis with 

 its viscera. Its anterior surface is concave, in consequence 

 of the concavity of the diaphragm against which the liver 

 rests on the right side, the stomach and the spleen mainly 

 on the left. 



On laying open the cavity from below at the linea 

 alba we expose the various viscera all covered by peri- 

 toneum, so that none of them can be touched except 

 after removal of their investing serous layer : it likewise 

 forms several double reflections around the viscera, which 

 serve to support the organs and which receive special 

 names. After covering the floor and the sides of the 

 belly it runs upwards posteriorly to be reflected to form 

 the ligaments of the bladder ; from the floor of the belly 

 along the central line a double fold runs to the fundus or 

 anterior portion of the bladder, being the susj^ensory liga- 

 ment. From the sides hroad ligaments run horizontally 

 to the fundus, and on the free margin of each between 

 the folds of peritoneum, is situated the round ligament 

 of the bladder, which in the foetus is the umbilical artery ; 

 it arises from the artery of the bulb, and in the adult 

 becomes impervious. The broad ligaments separate to 

 enclose the bladder, and the layer forming the ui)per surface 

 of these ligaments and covering the upper surface of the 

 bladder is posteriorly inflected upwards on to the under 

 surface of the commencement portion of the rectum and 

 the single colon, on either side of which the membrane 

 becomes firmly attached, superiorly forming by the union 

 of the two layers the meso-rectum, by which this portion 

 of the intestine is supported against the spine, and which 

 extends almost as far forwards as the stomach. On ar- 

 riving at the lumbar region it gives off a pouch on the 

 right side in which are enclosed the double colon and the 

 caecum and which forms the meso-colon, and the meso- 

 caecum, and another on the left in which the small intes- 

 tines lie, which is termed the mesentery ; from this pos- 

 teriorly a smaller fold extends on the right side around 



