590 



THE NERVUS TRIGEMINUS. 



Function. It is the voluntary motor nerve of the superior oblique muscle.- (In 



co-ordinated movements, how- 

 ever, it is involuntary.) 



Anastomoses. Its connections 

 with the plexus caroticus sympa- 

 thici, and with the first branch of 

 the trigeminus, have the same sig- 

 nificance as similar branches of the 

 oculomotorius. 



Pathological. Paralysis of the 

 trochlearis nerve causes a very slight 

 loss of the mobility of the eyeball 

 outwards and downwards. There 

 is slight squinting inwards and 

 upwards, with diplopia or double 

 vision. The images are placed 

 obliquely over each other [the false 

 image being the lower, and directed" 

 to the patient's right when the left 

 eye is affected (fig. 426, 6)] ; they 

 approach each other when the head 

 is turned towards the sound side, 

 and are separated when the head is 

 turned towards the other side. The 

 patient at first directs his head for- 

 wards, later he rotates it round a 

 vertical axis towards the sound side. 

 In rotatiug his head (whereby the 

 sound eye may retain the primary 

 position), the eye rotates with it. 

 Spasm of the trochlearis causes 

 squinting outwards and downwards. 



347. V. NERVUS TRIGEMI- 

 NUS. Anatomical. The trigemi- 

 nus (fig. 429, 5), arises like a spinal 

 nerve by two roots (fig. 428, V.) 

 The smaller, anterior, motor root 

 proceeds from the "motor tri- 

 geminal nucleus " (5), which is 

 provided with many multipolar 

 nerve-cells, and lies in the floor of 

 the medulla oblongata, not far from 



. the middle line. Fibres connect 

 Part of the base of the brain, with the brigins of the cranial this nucleus with the cortical motor 



nerves; the convolutions ot the island of Red on the ceil tres on the opposite side of the 

 right side, but removed on the left. I', olfactory tract cer ebrum. Besides this the "de- 

 cut short ; II, left optic nerve ; II , right optic tract ; 8ce nding root" also supplies motor 

 Th, cut surface ot the left optic thalamus; C, central tibres> It extends laterally from 

 lobe, or island of Red ; Sy, fissure of Sylvius; XX, the the corpora quadrigemina along the 

 locus perforatus anticus ; e, the external, and % the m- aque duct of Sylvius downwards to 

 terual corpus geniculatum ; h, hypophysis cerebn ; tc, the exit of the nerve [w m n Farel). 

 tuber cmereum, with the lufundibulum ; a, points to one The lar(re posterior sensory root 

 of the corpora albicantia ; P, the cerebral peduncle ; /, reC eives fibres :-(l) From the small 

 thenllet; III, left oculomotor nerve ; X, the locus per- cella of tue << sensory trigeminal 

 foratus posticus ; PV, pons Varolii ; V the greater part nuc i e us which lies at the level of 

 of the fifth nerve ; + , the lesser root (on the right side the pon and is the ana i gue of the 

 this mark is placed on the Gasserian ganglion and points p 0ster ior horn of the grey matter of 

 to the lesser root ; 1, ophthalmic division of the fifth ; { he 8pinal cord> (2) Fr </ n 

 \II a, facial, VII b, auditory ; VIII, vagus ; VIII a, 

 glossopharyngeal ; VIII b, spmal accessory; IX, hypo- 

 glossal ; Jl, flocculus ; fh, horizontal fissure of the cere- 

 bellum (Ce) ; am, amygdala ; pa, anterior pyramid ; o, 

 olivary body ; e, restiform body ; d, anterior median 

 fissure ; cl, the lateral column of the spinal cord ; CI, 

 the sub-occipital or first cervical nerve. 



the cerebellum, through the crura cerebelli. 



spinal cord. (2) From the grey 

 matter of the posterior horn of the 

 spinal cord, downwards as far as the 

 second cervical vertebra. These 

 fibres run into the posterior column 

 of the cord and then appear as the 

 "ascending root" in the trige- 

 minus. (3) Some fibres come from 

 The origins of the sensoiy root anastomose with 





