902 



THE NERVOUS SYSTEM 



3. The superior cervical sympathetic ganglion, which cells send axones chiefly by way 

 of the carotid plexus and the sympathetic roots of the cihary gangUon to terminat 

 about cells in — 



4. The ciliary ganglion. Such cells send axones into the ocular bulb to terminate in 

 the ciliary body and radial muscle fibres of the iris, producing dilation of the pupil. 



C. Auditory-eye reflexes. 



1. Cells of the nuclei of termination of the cochlear nerve and superior olive send fibres 

 by way of the medial longitudinal fasciculus (some to this by way of the peduncle 

 of the superior ohve) to the nuclei of origin of the eye-moving nerves. 



2. The same nuclei of the cochlear nerve send axones by way of the lateral lemniscus 

 to terminate in the superior quadrigeminate body and thence may be sent impidsea 

 which are distributed to the nuclei of the eye-moving nerves 



IX. Principal Conduction Paths of Olfactory Apparatus 



1. Bipolar cells of olfactory region of nasal epithelium send short (peripheral) processes 

 toward surface of nasal cavity and centrally directed processes, the olfactory nerve, 

 through lamina cribrosa of ethmoid bone into olfactory bulb (glomerular layer). 



2. 'Mitral cells' of olfactory bulb give fibres which form — 

 (o) The olfactory tract which divides into— 



Fig. 710. — Diagram Showing Some of the Principal Tracts and Synapses of the Olfac- 

 tory Apparatus. 



Fornix 



Anterior comimssure 

 Subcallosal gyra 

 Parolfactory area 



Gyrus rectus ^ 



Olfactory tract 

 Olfactory bulb 



Perforating fibres 



\ Medullary stria of thalamus 



, Gyrus cinguli 

 Cingulum 



^ Longitudinal striae 

 on corpus callosum 



Hippocampal com- 

 missure (Lyre) 



Anterior thalamic 

 nucleus 



~* Habenular nucleus 



Habenulo-pedun- 

 . cular tract (fasci- 

 culus retroflexus) 



Mammillo-mesen- 

 ,N cephalic fasciculus 



■ -"^x Penduculo-tegmental 



tract 

 Interpeduncular nucleus 



Uncus 



\ Fimbria hippocampi 

 Mammillary body 

 Anterior perforated substance 



Olfactory epithelium 



(b) Medial olfactory stria through which fibres pass — ^(1) into parolfactory area (Broca's 

 area); (2) into subcallosal gyrus; and (3) by way of anterior cerebral commissure 

 to olfactory bulb and uncus of hippocampal gyrus of opposite side. 



(c) Intermediate olfactory stria to anterior perforated substance. 



(d) Lateral olfactory stria, which terminates to some extent in anterior perforated 



substance, but chiefly in uncus, hippocampal gyrus, and gyrus cinguli (olfactory 

 area) of same side. 



3. Cells of uncus and hippocampal gyrus give fibres which form — 



(a) The cingulum (in part), by which they are associated with the cortex of the gyrus 

 cinguli and other areas of the cerebral cortex. 



(6) The hippocampal commissure (in part), by which they are connected with the grey 

 substance of the opposite side. 



(c) The fornix, which, interrupted in part in the nuclei of the corpus mammillare, 

 conveys impulses — (1) to the anterior nucleus of thalamus of the same (chiefly) 

 and opposite sides (mammillo-thalamic fasciculus), and (2) into the mesencephalon 

 and substantia nigra (mammillo-raesencephalic fasciculus), and by way of this 

 tract probably to the nuclei of the mesencephalon and medulla oblongata. 



4. The parolfactory area, anterior perforated substance, anterior portion of thalamus and 

 fornix give fibres which form the medullary stria of the thalamus and which terminate 

 in the ludxiniilar nucleus. 



o. Habenular nucleus sends fibres in fasciculus retroflexus to terminate in interpeduncular 



nucleus. 

 6. Interpeduncular nucleus sends fibres to nuclei of mesencephalon and probably to 



structures below it. 



