100 NERVOUS SYSTEM. 



and there are in the nerves a considerable number of non-medul- 

 lated fibres more than in the spinal nerves. 



Do the sympathetic nerves differ materially from the cerebro- 

 spinal ? 



No. They are very similar. The occurrence of ganglia upon 

 the sensory branch of the spinal nerves and upon the sensory cra- 

 nial nerves (pneumogastric, glosso-pharyngeal, and trigeminus) adds 

 to the similarity. Then, too, the frequent communications be- 

 tween the two systems practically makes one system of them, and 

 the division is largely one for convenience. 



Is the sympathetic system dependent upon its connection with 

 spinal axis? 



Yes. 



Where are the functions of the sympathetic system most shown ? 

 In the organs of nutrition and secretion and in the vascular 



What are the sympathetic ganglia in the head? 



They are four in number ophthalmic, spheno-palatine, submax- 

 illary, and otic ganglia. Each has communications from the gen- 

 eral sympathetic, and from the cranial nerves both motor and sen- 

 sory fibres. 



Describe the ophthalmic ganglion. 



It is a small ganglion situated in the orbit, and receives com- 

 munications from the sympathetic and from the motor oculi 

 (third) . nerve, a motor branch, and from the trigeminus (fifth) 

 nerve a sensory branch. Its branches pass into the eyeball (ciliary 

 nerves), and are distributed in the iris. Their function is the con- 

 trol of the pupil, of the apparatus of accommodation, and of the 

 vaso-motor function in the vessels of the eye. 



Describe the spheno-palatine ganglion. 



It is situated in the spheno-maxillary fossa, and receives branches 

 from the cervical sympathetic system and motor fibres from the 

 facial (seventh) nerve, and sensory from the fifth. Its branches are 

 distributed to the mucous membrane and muscles of the palate 

 and uvula, and to the naso-pharynx. They are both sensory and 

 motor. 



