CHAPTER VIII 



THE HIND-BKAIN 



CONTENTS. 1. Anatomy of hind-brain : afferent and efferent tracts of the three 

 cerebellar peduncles. 2. Preliminary observations on cerebellar functions. 3. Dy- 

 namic phenomena immediately incident on removal of cerebellum. 4. Cerebellar 

 ataxy in dogs and monkeys after removal of half the cerebellum. 5. Cerebellar 

 ataxy after total removal of cerebellum. 6. Cerebellar ataxy. 7. The cerebellum 

 as the centre of equilibrium ; i 8. And the co-ordinating organ of voluntary 

 movements ; 9. And the organ of subconscious sensations, exercising constant 

 reinforcing action upon the other nerve-centres. 10. Localisation of cerebellar 

 functions. Bibliography. 



IN discussing the medulla oblongata we were obliged to include 

 the pons Varolii, which, both in its structure and its functions, 

 is the continuation of the bulb. Embryclogically, however, while 

 the medulla oblongata arises from the 5th secondary vesicle, the 

 pons and cerebellum originate in the 4th secondary vesicle, and 

 form respectively the ventral and dorsal parts of the Hind-brain 

 or Melencephalon. 



I. The Hind-brain is more developed in mammals than in other 



ERRATUM 



Page 419, par. 1, line 7, for " Mesencephalon " read " Metencephalon. " 



restilorm bodies or interior cerebellar peduncles, and the brachia 

 conjunctiva or superior cerebellar peduncles (Figs. 201, 202). In 

 association with this thickening of the middle peduncles the 

 mammalian cerebellum has, besides a median lobe or vermis, 

 lateral lobes or cerebellar hemispheres, which do not exist, or are 

 rudimentary, in the lower vertebrates. This increased develop- 

 ment of the hind-brain in mammals is counterbalanced by a con- 

 siderable relative reduction in the mid-brain, in comparison with 

 that of the lower vertebrates. 



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