130 TOPOGRAPHICAL ANATOMY OF THE 



to the pylorus and the commencement of the duodenum and the 

 pancreas. Some few filaments follow the bile duct to the liver and 

 unite with the hepatic plexus. 



Truncus (ESOPHAGEUS dorsalis. — The dorsal tesophageal trunk 

 receives the majority of its fibres from the right vagus nerve, and is 

 distributed over the caudal surface and saccus ca-cus of the stomach. 

 Its filaments unite with those of the ventral trunk in the formation of 

 the gastric plexus. A strong nerve joins the cot^liaco-mesenteric ganglia 

 and the coeliac plexus. 



Ganglia cceliacomesenterica. — In the horse a large ganglion, on 

 each side of the ventral border of the aorta between the origins of the 

 cceliac and cranial mesenteric arteries, represents the combined cosliac 

 and cranial mesenteric ganglia. The right ganglion is entirely covered 

 on its ventral aspect by the vena cava ; while the left ganglion is partly 

 covered by the left adrenal. The right and left ganglia are connected 

 with each other by a plexus of filaments that embraces the cranial 

 mesenteric artery. 



As has just been stated, the dorsal oesophageal trunk is connected 

 with the ganglia, as are also the greater splanchnic nerves that, formed 

 in the thorax, gain the abdomen by crossing the edge of the diaphragm 

 ventral to the psoas minor muscle. 



Radiating from the ganglia are the coeliac and cranial mesenteric 

 plexuses, with which hepatic, gastric, splenic, aortic and renal plexuses 

 are connected. The coeliac plexus forms an intricate feltwork of fibres 

 with the coeliaco-mesenteric ganglia as a centre. Connected with it are 

 filaments from the vagus and splanchnic nerves, and from some of the 

 lumbar sympathetic ganglia. The hepatic, gastric, splenic, aortic and 

 renal plexuses are associated with the like-named arteries. A spermatic 

 plexus (or utero-ovarian plexus in the female), on each side of the body, 

 is formed by fibres derived from the aortic plexus and the caudal 

 mesenteric ganglion, and accompanies the spermatic (or utero-ovarian) 

 artery to the testis (or ovary and uterine cornu). 



Ganglion mesentericum caudale. — A relatively small unpaired 

 caudal mesenteric ganglion will be found close to the origin of the 

 caudal mesenteric artery. Two stout nerve cords connect this ganglion 

 with the coeliaco-mesenteric ganglia. The caudal mesenteric plexus 

 radiates from the like-named ganglion, and is connected with the left 

 colic and cranial haemorrhoidal plexuses which accompany the vessels of 

 the same name. An internal spermatic nerve (n. spermaticus internus) 

 leaves the caudal mesenteric ganglion and follows the internal spermatic 



