514 ABDOMEN 



The peritoneal investment adheres so closely to the subjacent fibrous coat 

 that it can only be removed with difficulty. With regard to the fibro-elastic 

 tunic (tunica propria), it should be noted that processes proceed from its 

 deep surface and dip into the substance of the organ. These are the 

 trabeculce, and they constitute the supporting framework of the gland-ipulp. 

 On account of this arrangement, it will be found utterly impossible to strip 

 off the fibrous coat of the spleen without at the same time lacerating its 

 surface. Make a section through the organ, and carry a portion off it to 

 the tap. By squeezing it and allowing the water to run freely over it, a 

 view of the trabecular framework may be obtained. 



Dissection. The sympathetic plexuses of the upper part of the abdomen 

 may now be studied with advantage. Throw the tail and body of the 

 pancreas and the first part of the duodenum over to the right. Next turn 

 to the left c'oeliac ganglion, which was displayed when the posterior wall of 

 the omental bursa was removed, lying between the left border of the cceliac 

 artery and the medial border of the left suprarenal gland (see p. 460). 

 From the medial border of the left coeliac ganglion trace sympathetic nerve 

 fibres across the front of the aorta round the root of the coeliac artery to 

 the opposite ganglion which lies behind the inferior vena cava. To expose 

 the right coeliac ganglion, therefore, it is necessary to displace to the right 

 the portion of the inferior vena cava which lies behind the first part of the 

 duodenum and to fix it out of the way with hooks or pins. Follow each 

 cceliac ganglion upwards and backwards to its union with the great 

 splanchnic nerve of the same side, and follow the splanchnic nerve to the 

 point where it passes into the abdomen by piercing the cms of the 

 diaphragm of the corresponding side. 



Sympathetic Plexuses. In connection with the sympa- 

 thetic nervous system three large plexuses are formed in front 

 of the vertebral column : they are the cardiac plexus in 

 the thorax, the coeliac or solar plexus in the upper part of the 

 abdomen proper, and the hypogastric plexus in the lower part 

 of the abdomen proper. 



The Coeliac or Solar Plexus, which is by far the largest of 

 the three, consists of the two coeliac (O.T. semilunar) ganglia 

 and the numerous nerve bundles which connect the ganglia 

 together. 



It lies at the level of the lower part of the last dorsal and 

 the upper part of the first lumbar vertebra in front of the 

 crura of the diaphragm and the uppermost part of the 

 abdominal portion of the aorta, between the medial margins 

 of the suprarenal glands, and around the coeliac artery. 

 Numerous offshoots arise from it and pass either along the 

 adjacent arteries, or to the suprarenal glands and the kidneys ; 

 these constitute secondary plexuses. 



Ganglia Cceliaca (O.T. Semilunar Ganglia). The coeliac 

 ganglia are of irregular shape, and they are so large that 

 they are frequently mistaken by students for lymphatic glands. 



