(SYMPATHETIC NEEVOUS SYSTEM. 871 



a. The anterior ceivical ganglion is an elongated 

 ;pink ganglion lying to the inner side of the 

 ganglionic enlargement of the pneumogastric 

 nerve, and slightly ventral to this. It is partially 

 hidden by the stylomastoid muscle, and is by 

 far the largest of the cervical ganglia. 



b. The middle cervical ganglion is a fusiform 



thickening of the sympathetic cord immediately 

 in front of the subclavian artery. 



c. The posterior cervical ganglion, vpith which is 



usually fused the first thoracic ganglion, is a 

 stellate ganglion, lying dorsal to the subclavian 

 artery, and between this and the first rib ; it 

 receives branches from the last cervical and 

 first one or more thoracic spinal nerves. 



2. The thoracic portion of the gangliated cord of each 



side runs along the inner surface of the dorsal wall 

 of the thoracic cavity, crossing the heads of the ribs. 

 Small ganglia are developed on it at the points where 

 it receives branches from the several thoracic spinal 

 nerves. Of these ganglia the first is usually fused 

 with the posterior cervical ganglion, and other 

 variations may occur. 



The posterior part of the thoracic portion of the sym- 

 pathetic iiervous system is readily exposed by turning the lung 

 over to the opposite side ; the anterior portion is closely con 

 nected with the vessels and other structures at the anterior 

 end of the thorax, and requires careful dissection, 



3. The abdominal portion of the gangliated cord of each 



side runs along the sides of the bodies of the lumbar 

 vertebree, and is continued through the pelvic region 

 into the tail. It has ganglionic enlargements at the 

 places where it receives branches from the several 

 spinal nerves. 



B. The abdominal plexuses are formed by nerves which are 

 given off from the ganglia of the main longitudinal cords. 



B B 2 



