TRIGEMINAL NERVE. 687 



have demonstrated that an intimate physiological connection exists between ' the 

 vascular distribution in the two eyes, so that affections in the vascular distribu- 

 tion of one eye readily excite analogous affections in the other eye. This fact 

 explains why inflammatory processes chiefly in the interior of one eyeball give 

 rise to so-called sympathetic ophthalmia in the other eyeball. Thus, irritants 

 affecting the ciliary nerves or the fifth nerve upon one side cause at the same 

 time dilatation of the vessels in the other eye, together with its sequelae. The 

 pathological excessive tension of the eye, with its sequelae (simple glaucoma), is 

 worthy of mention and has been attributed by Bonders to irritation of the trigem- 

 inus. Unilateral flow of tears has been observed repeatedly in conjunction with 

 irritative states of the first division of the trigeminus and unilateral suppression 

 of tears, but rarely in association with paralytic states. 



The second, or superior maxillary, division (Fig. 243, e) gives off: 



1. The slender recurrent nerve, a sensory branch to the dura mater, 

 which in the distribution of the middle meningeal artery accompanies 

 the vasomotor nerves of this vessel derived from the superior cervical 

 ganglion of the sympathetic. Irritation of this nerve causes also reflex 

 closure of the lids in the frog. 



2. The subcutaneus mal<z, or orbital nerve (c), supplies with its two 

 branches, the temporal and the orbital, the external canthus of the eye 

 and the adjacent cutaneous area of the temple and the cheek, with sensory 

 fibers. Some of the filaments of the nerve are said to be true secretory 

 nerves for the tears. 



3. The posterior and median superior alveolar nerves, and with them 

 the anterior from the infraorbital nerve, give off sensory fibers to the 

 teeth of the upper jaw, the gums, the periosteum and the maxillary 

 ant rum. The vasomotor nerves for all of these parts are supplied by the 

 superior cervical ganglion of the sympathetic. 



4. The infraorbital nerve (R), which, after its exit from the infraorbi- 

 tal foramen, distributes sensory fibers to the lower eyelid, the bridge and 

 alae of the nose and the upper lip to the angle of the mouth. The ac- 

 companying arteries receive vasomotor fibers from the superior cervical 

 ganglion of the sympathetic. The sweat-fibers in swine are described 

 on p. 537. 



The sphenopalatine, or basal ganglion (n), is connected with the sec- 

 ond branch of the trigeminus. It contains cells arranged like those of the 

 sympathetic ganglia. To it pass, first, with one or several filaments, 

 short sensory root -fibers from the second branch itself, which are desig- 

 nated sphenopalatine nerves. Motor fibers pass from behind into the 

 ganglion through the greater superficial petrosal nerve from the facial 

 (j) and finally gray vasomotor fibers from the sympathetic plexus of the 

 carotid (greater deep petrosal nerve). The motor and vasomotor fibers 

 form the Vidian nerve, which passes through the Vidian canal to the 

 ganglion. The ganglion gives off the following fibers: 



i. The sensory fibers (N) supply the roof, the lateral walls, and the 

 septum of the cavity of the nose (posterior superior nasal nerves). The 

 nasopalatine nerve passes through the incisor canal with its terminal 

 filaments to the hard palate behind the incisor teeth. The sensory pos- 

 terior inferior nasal nerves for the lower and middle turbinates and the 

 two lower nasal passages are derived from the anterior palatine nerve of 

 the ganglion, which descends in the pterygopalatine canal. Finally, the 

 sensory branches for the hard (p), and the soft palate (p t ) and the tonsil 

 are derived from the descending posterior palatine nerve. Irritation of 

 any of the sensory fibers of the nose causes reflex sneezing, which is 



