386 



GENERAL STRUCTURE AND FUNCTIONS 



or tuberosity, which is known by the name of the tuber annulare. 

 In the deeper portions of this protuberance there is situated, among 

 the longitudinal fibres, another collection of gray matter, which 

 though not of large size, has very important functions and connec- 

 tions. This is known as the ganglion of the tuber annulare. 



Situated almost immediately above these parts we have the cor- 

 pora striata in front, and the optic thalami behind, nearly equal in 

 size, and giving passage, as above described, to the fibres of the 

 anterior and posterior columns. Behind them still, and on a little 

 lower level, are the tubercula quadrigemina, giving origin to the 

 optic nerves. The olfactory ganglia rest upon the cribriform plate 

 of the ethmoid bone, and send the olfactory filaments through the 

 perforations in this plate, to be distributed upon the mucous mem- 

 brane of the upper and middle turbinated bones. The cerebellum 

 covers in the fourth ventricle and the posterior surface of the 

 medulla oblongata ; and finally the cerebrum, which has attained 

 the size of the largest ganglion in the cranial cavity, extends so far 

 in all directions, forward, backward, and laterally, as to form a con- 

 voluted arch or vault, completely covering all the remaining parts 

 of the encephalon. 



The entire brain may therefore be regarded as a connected series 



of ganglia, the arrangement of 



Fi g- 131. which is shown in the accompany- 



ing diagram. (Fig. 131.) These 

 ganglia occur in the following 

 order, counting from before back- 

 ward: 1st. The olfactory gan- 

 glia. 2d. The cerebrum or hemi- 

 spheres. 3d. The corpora striata. 

 4th. The optic thalami. oth. The 

 tubercula quadrigemina. 6th. 

 The cerebellum. 7th. The gan- 

 glion of the tuber annulare. And 

 8th. The ganglion of the medulla 

 oblongata. Of these ganglia, 

 only the hemispheres and cere- 

 bellum are convoluted, while the 

 remainder are smooth and round- 

 ed or somewhat irregular in 

 shape. The course of the fibres 

 coming from the anterior and posterior columns of the cord is also 



Diagram of HUMAN BRAIN, in vertical sec- 

 tion; showing the situation of the different gan- 

 glia, and the course of the fibres. 1. Olfactory 

 ganglion. 2 Hemisphere. 3. Corpus striatum. 

 4. Optic thalamus. 5. Tubercula quadrigemina. 

 6. Cerebellum. 7. Ganglion of tuber anuulare. 

 8. Ganglion of medulla oblongata. 



