372 DISSECTION OF TAB RABBIT. 



They are mostly composed of non-meduUated fibres, and are 

 hence difficult to follow. The principal components of these 

 plexuses are the following. 



1. The greater splanchnic nerve arises from the ninth 



and tenth thoracic ganglia, and runs backwards 

 through the dorsal portion of the diaphragm to end 

 in the coeliac ganglion. 



2. The lesser splanchnic nerve arises from the eleventh 



and twelfth thoracic ganglia, and runs alongside the 

 greater splanchnic nerve to the coeliac ganglion. 



3. The ooeliac ganglion is a flattened oval body of a pinkish 



colour, lying in the mesentery immediately in front 

 of the anterior mesenteric artery, and about an inch 

 from the aorta. It receives the greater and lesser 

 splanchnic nerves of both sides. 



4. The anterior mesenteric ganglion, which is also un- 



paired, lies in the mesentery immediately behind the 

 anterior mesenteric artery, and close to the coeliac 

 ganglion, with which it is connected by several 

 nerves. 



5. The posterior mesenteric ganglion lies in the mesentery 



upon the posterior mesenteric artery close to the 

 point where this branches out to supply the rectum. 

 It is connected with the anterior mesenteric ganglion 

 by nerves which can be seen running in the mesentfery 

 parallel to its dorsal edge. 



From these three ganglia of the mesentery, nerves are 

 ' given off which form plexuses supplying the abdominal 

 portion of the digestive system. These nerves and plexuses 

 are closely associated with the arteries, but it is nearly im- 

 possible to follow them to their distribution. 



IX. DISSECTION OF TH]S HEAD. 



Remove the skin from the head. Loaj the rabbit on its 

 right side : insert one blade of the scissors into its mouth. 



