46 NERVOUS SYSTEM. 



Thoracic Portion of the Sympathetic (Fig. 157, page 381). 

 -The inferior cervical ganglion (e) lies entirely within the 

 thoracic cavity. It has the following branches: 



1. One or two small cardiac branches (/*), which pass to 

 the heart (r). 



2. A large communicating branch (e'), which passes 

 craniad from the cranial end of the ganglion (e) along the 

 lateral surface of the longus colli muscle, and gives communi- 

 cating branches to the sixth, seventh, and eighth cervical 

 nerves ( VI, VII, and VIII}. 



3. One or two small communicating branches to the first 

 thoracic nerve (/'). 



4. A communicating branch to the second thoracic nerve. 

 The arrangement of these communicating branches is 



somewhat variable ; they may arise in various combinations, as 

 at first united, or as more or less completely separated nerves. 



The sympathetic trunk (c} continues caudad from the caudal 

 end of the inferior cervical ganglion, lying at first on the lateral 

 surface of the longus colli, then on the lateral surface of the 

 centra of the vertebrae. For each vertebra there is a slight 

 enlargement, forming one of the thoracic ganglia of the sym- 

 pathetic, and from each ganglion one or two communicating 

 branches are given off to the corresponding spinal nerve. Just 

 caudad of the last rib (but while still in the thoracic cavity) 

 the sympathetic gives off the large N. splanchnicus major or 

 great splanchnic nerve (n\, which passes ventrocaudad and 

 pierces the diaphragm. The sympathetic itself then passes 

 through the diaphragm laterad of the crus. 



Abdominal Portion of the Sympathetic (Fig. 164). The 

 great splanchnic nerve (b} passes through the diaphragm (2) 

 laterad of the crus, extends two or three centimeters caudoven- 

 trad, and joins a large ganglion lying just caudad of the cceliac 

 artery (4), almost on the lateral surface of the superior mesen- 

 teric (5). This is the cceliac (or semilunar) ganglion (</). 

 From it nerves branch in all directions, forming the coeliac 

 plexus (e), a part of the large solar plexus. Less than a 

 centimeter ventrocaudad of the cceliac ganglion, on the caudal 

 surface of the superior mesenteric artery (s), is the somewhat 



