648 TEXT-BOOK OF PHYSIOLOGY 



vessels and glands of the nose and mouth and to the blood-vessels and 

 epithelium of the submaxillary and sublingual glands respectively. 



The pre-ganglionic fibers that leave by way of the glosso-pharyngeal 

 nerve pass into the tympanic branch or nerve of Jacobson and ulti- 

 mately arborize around the cells of the otic ganglion. The gray post- 

 ganglionic fibers which arise in the cells of this ganglion pass by way of 

 the auriculo-temporal branch of the trigeminal nerve to the blood-vessels 

 and epithelium of the parotid gland. 



The pre-ganglionic fibers that leave in the trunk of the vagus nerve 

 are ultimately distributed to the ganglia of the heart, stomach, small 

 intestine, etc., around the nerve-cells of which their terminal branches 

 arborize. The gray post-ganglionic fibers which arise in these ganglia 

 pass to the heart-fibers, to the non-striated muscle -fibers in the walls of 

 the stomach, intestines, etc. These fibers contained in the facial, glosso- 

 pharyngeal and vagus nerves, together with their ganglionic continua- 

 tions, have collectively been termed the bulbar autonomic system. 

 Together with the fibers in the oculo-motor nerve they have been termed 

 the cranio-bulbar autonomic system. 



3. The Mid-spinal Cord Region. The pre-ganglionic nerve-fibers that 

 leave the spinal cord in this region arise from groups of nerve-cells situ- 

 ated in the gray matter between the levels of origin of the second thoracic 

 and the second and third, perhaps the fourth, lumbar nerves. From this 

 origin the fine pre-ganglionic fibers emerge from the cord in the ventral 

 roots of the thoracic and upper lumbar nerves and hence naturally fall 

 into two groups, viz.: the thoracic and the lumbar. Both groups of 

 nerves accompany the ventral motor roots of the spinal nerves to about 

 the point where each nerve divides into an anterior and a posterior 

 branch; they then leave and enter the vertebral or sympathetic chain 

 of ganglia. The branches of communication are known as the white 

 rami communicantes. The nerve-fibers composing these communicating 

 branches all terminate around the nerve-cells of the ganglia at the same 

 and at somewhat different levels and in different regions. 



The thoracic pre-ganglionic fibers in accordance with their distribu- 

 tion may be divided into five groups, viz. : 



(a) Those fibers which emerge from the spinal cord in each of the tho- 

 racic nerves and which terminate around the cells of the ganglia at 

 the same level. 



(b) Those fibers which emerge from the spinal cord in the thoracic 

 nerves from the fourth to the tenth and which after entering the 

 vertebral chain turn upward and finally terminate around the cells 

 of the first thoracic or stellate ganglion. 



(c) Those fibers which emerge from the cord in the second and third 

 thoracic nerves and which after entering the vertebral chain turn 

 upward and terminate around the cells of the inferior cervical gan- 

 glion. '. 



(d) Those fibers which emerge from the cord in the second, third and 

 perhaps the fourth thoracic nerves and which, after entering the 

 vertebral chain turn upward and pass through the various ganglia 

 and cord and finally terminate around the cells of the superior cer- 

 vical ganglion. 



