638 



NERVOUS SYSTEM. 



The terminal branches upon the face are distributed to the lower eyelid (the palpebral 

 branches) ; to the side of the nose (the nasal branches), anastomosing with the nasal 

 branch of the ophthalmic ; and to the integument and mucous membrane of the upper 

 lip (the labial branches). 



The inferior maxillary is a mixed nerve, composed of the inferior division of the large 

 root and the entire small root. The distribution of the motor filaments has already been 

 described under the head of the nerve of mastication. This nerve passes out of the cranial 

 cavity by the foramen ovale, and then separates into the anterior division, containing 

 nearly all of the motor filaments, and the posterior division, which is chiefly sensory. 

 The sensory portion breaks up into numerous branches : 



1. The auriculo-temporal nerve supplies the integument in the temporal region, the 

 auditory meatus and the integument of the ear, the temporo-maxillary articulation, and 

 the parotid gland. It also sends important branches of communication to the facial. 



2. The lingual branch is distributed to the mucous 

 membrane of the tongue as far as the point, the mucous 

 membrane of the mouth, the gums, and to the sublingual 

 gland. This nerve receives an important branch from 

 the facial (the chorda tympani) which has already been 

 described. From this nerve, also, are given off two or 

 three branches which pass to the subm axillary ganglion, 

 constituting its sensory roots. 



3. The inferior dental nerve, the largest of the three, 

 passes in the substance of the inferior maxillary bone, 

 beneath the teeth, to the mental foramen, where it 

 emerges upon the face. The most important sensory 

 branches are those which supply the pulps of the teeth, 

 and the branches upon the face. The nerve, emerging 

 upon the face by the mental foramen, called the mental 

 nerve, supplies the integument of the chin and the lower 

 part of the face, the lower lip, and sends certain filaments 

 to the mucous membrane of the mouth. 



FIG. 215. Limits of cutaneous distri- 

 bution of sensory nerves to the face, 

 head, and neck. (Beclard.) 



1, cutaneous distribution of the ophthal- 

 mic division of the fifth ; 2, distribu- 

 tion of the superior maxillary divi- 

 sion ; 3, 3, distribution of the inferior 

 maxillary division ; 4, distribution of 

 the anterior branches of the cervical 

 nerves ; 5, 5, distribution of the pos- 

 terior branches of the cervical nerves. 



Properties and Functions of the Trifacial. In 1822, 

 Herbert Mayo published an account of " experiments to 

 determine the influence of the portio dura of the sev- 

 enth, and of the facial branches of the fifth pair of 

 nerves." These experiments consisted in dividing the infra-orbital, inferior maxillary 

 and frontal branches of the fifth, and the branch from the fifth to the seventh, in asses, 

 by which it was demonstrated that these were exclusively sensory nerves. In a second 

 publication, the following year, it is stated that the root of the fifth was divided in the 

 cranial cavity in pigeons ; but this was with reference chiefly to the movements of the 

 iris, although Mayo notes that after division of the nerve " the surface of the eyeball ap- 

 pears to have lost its feeling." 



In 1823, Fodera published an account of experiments in which he had divided the 

 roots of the fifth in living animals (rabbits) by introducing a small knife through an 

 opening in the parietal bone, along the base of the skull, and cutting through the roots 

 near the Gasserian ganglion. The operation was followed by complete loss of sensibil- 

 ity upon the side on which the nerve had been divided. In this and other experiments, 

 however, the animals died a short time after the operation. The paper in which these 

 experiments were detailed was presented to the Academy of Sciences, December 31, 1822, 

 and was published at about the same time as the experiments of Mayo. 



In 1824, Magendie published an account of his experiments upon the fifth pair. He 

 divided the nerve at its root, by introducing a small stylet through the skull, and noted 



