424 Anatomy Applied to Medicine and Surgery. 



in all probability, in the posterior parts of the third and 

 fourth temporal convolutions. The centres for taste and 

 smell are situated in the region of the hippocampal gyrus. 



Arrangement of the Fibres of the Cerebrum, In- 

 ternal Capsule, etc. There are two sets of fibres in 

 the brain one, commisural or association fibres, and the 

 other, projection fibres. The former, i.e., the commisural 

 fibres, unite different convolutions as well as the different 

 parts of one hemisphere together, or they unite the two 

 hemispheres together, as in the case of the corpus callo- 

 sum and the commisures. These fibres, as their name 

 indicates, no doubt harmonize and associate the different 

 portions of one hemisphere with each other, or one hemi- 

 sphere itself with the other. 



Projection Fibres. These are fibres, which run from 

 the cortex or generating portions of the brain to their dis- 

 tribution in the optic thalamus, corpus striatum, pons, 

 medulla and cord. Inasmuch as the outlet or avenue, 

 through which they find exit from the brain, is very nar- 

 row as compared with the extent of origin of these pro- 

 jection fibres, it follows, that to pass down to the medulla, 

 cord, etc., they must be collected into as small a bulk as 

 possible where they leave the brain, and the portion of the 

 brain at which this concentration occurs is the internal 

 capsule. We might liken the arrangement of these fibres 

 to the household broom, the expanded end of which repre- 

 sents the cortical origin of the projection fibres, and the 

 end of the handle, to which the broom top is affixed, the 

 internal capsule. Some of these projection fibres, in pass- 

 ing downwards to the base of the brain, cut through the 

 corpus striatum, dividing it into two parts, an internal 

 the caudate nucleus, and an external the lenticular nuc- 

 leus, while the remainder of these projection fibres find 

 exit from the cerebrum between the optic thalamus inter- 



