572 NERVOUS SYSTEM. 



the nose, mouth and ear are rendered hyperaemic, the temperature probably 

 is raised, and the processes of nutrition are exaggerated. This condition 

 of the parts would seem to require a full supply of nutritive material from 

 the blood, in order to maintain the condition of exaggerated nutrition ; but 

 when the blood is impoverished probably as the result of deficiency in the 

 introduction of nutritive matter, from paralysis of the muscles of mastication 

 upon one side the nutritive processes in these delicate parts are seriously 

 modified, so as to constitute inflammation. The observation just detailed is 

 an argument in favor of this view ; for here the inflammation was arrested 

 when the action of the paralyzed muscles was supplied by careful feeding. 

 With this view, the disorders of nutrition observed after division of the fifth 

 may properly be referred to the sympathetic system. 



Pathological facts in confirmation of experiments upon the fifth pair in 

 the lower animals are not wanting ; but it must be remembered that in cases 

 of paralysis of the nerve in the human subject, it is not always possible to 

 locate exactly the seat of the lesion and to appreciate fully its extent, as can 

 be done when the nerve is divided by an operation. In studying these cases, 

 it sometimes occurs that the phenomena, particularly those of modified nutri- 

 tion, are more or less contradictory. 



In nearly all works upon physiology, are references to cases of paralysis 

 of the fifth in the human subject. Two cases have been reported by Noyes, 

 in both of which there was inflammation of the eye. In one case the tongue 

 was entirely insensible upon one side, but there was no impairment of the 

 sense of taste. A notable feature in one of the cases was the fact that an 

 operation upon the eyelid of the affected side was performed without the 

 slightest evidence of pain on the part of the patient. 



Cases of paralysis of the fifth in the human subject in the main confirm 

 the results of experiments upon the inferior animals. In cases in which the 

 fifth nerve alone is involved in the disease, without the facial, there is simply 

 loss of sensibility upon one side, the movements of the superficial muscles 

 of the face being unaffected. When the small root is involved, the muscles 

 of mastication upon one side are paralyzed ; but in certain reported cases in 

 which this root escaped, there was no muscular paralysis. The senses of 

 sight, hearing and smell, except as they were affected by consecutive inflam- 

 mation, are little if at all disturbed in uncomplicated cases. The sense of 

 taste in the anterior portion of the tongue is perfect, except in those cases in 

 which the facial, the chorda tympani or the lingual branch of the fifth after 

 it had been joined by the chorda tympani is involved in the disease. In 

 some cases there is no alteration in the nutrition of the organs of special 

 sense ; but in this respect the facts with regard to the seat of the lesion are 

 not so satisfactory as in experiments upon the lower animals, it being diffi- 

 cult, in most of them, to exactly limit the boundaries of the lesion. 



PNEUMOGASTRIC (TENTH NERVE). 



Of all the nerves emerging from the cranial cavity, the pneumogastric 

 presents the greatest number of anastomoses, the most remarkable course and 



