THE NERVOUS SYSTEM 243 



just craniad of the diaphragm and extends to a group of ganglia 

 in the region of the trunk of the celiac axis (Figs. ii6 and 117). 

 These ganglia and anastomosing branches constitute the solar 

 or epigastric plexus, lying dorsad of the stomach, to which it 

 sends numerous branches. This plexus also receives the lesser 

 splanchnic nerve coming from the sympathetic cord just 

 craniad of the diaphragm, and branches from the tenth cranial 

 nerve. 



The largest ganglion of the solar plexus is the celiac or semi- 

 lunar. The solar and its allied plexuses send nerves to the dia- 

 phragm, suprarenal bodies, many of the blood-vessels of the 

 abdominal cavity, stomach, kidneys, ureters, testes or ovaries, 

 uterus, liver, gall-bladder, spleen, pancreas, and intestines. 



The hypogastric plexus is the third great sympathetic plexus. 

 It lies on the ventral aspect of the two caudal lumbar vertebrae 

 and is formed by branches from the solar plexus and a few twigs 

 form the sympathetic cords. It supplies the blood-vessels of 

 the pelvic region and all the organs of the pelvis. The sym- 

 pathetic cords in the lumbar region lie near together and the 

 communicating branches between them and the spinal nerves 

 are longer than in the thoracic region. In the sacral region 

 there are no rami communicantes, and the ganglia are irregularly 

 arranged. A median ganglion in the sacraL region is known as 

 the ganglion impar. There may be two median ganglia. The 

 sympathetic cords terminate in the tail. 



LABORATORY STUDIES AND SUGGESTIONS 



1. Name the foramina of the skull giving passage to one or more cranial 

 nerves. 



2. From a study of one or more specimens and the description in the book 

 make a diagrammatic drawing of each cranial nerve. 



3. Which cranial nerves have their roots in the medulla? 



4. Name the cranial nerves which are wholly motor. 



5. Which of the cranial nerves do not supply structures of the head? 



6. Of what are ganglia composed? 



7. Make a drawing of your dissection showing the connection between the 

 spinal and sympathetic nerves. 



