Chap. XXIII.] 



OF THE HUMAN BRAIN. 



455 



to the convolutions forming the tip and inner or under sur- 

 face of the Temporal Lobe. It is, as Broadbent says, and 

 as other anato- 

 mists had pre- 

 viously recog- 

 nized, a sort of 

 accessory Cor- 

 pus Callosum 

 connecting 

 those parts of 

 the two Tem- 

 poral Lobes 

 which could not 

 otherwise be 

 easily brought 

 into relation 

 with one an- 

 other. 



In some of 

 the lower ani- 

 mals that have 

 large Olfactory 

 Lobes and 

 ' tracts,' these 

 are directly con- 

 nected with one 

 another by 

 means of fibres 

 which form part 

 of this Anterior 

 Commissure. 



The Middle Commissure is a soft 

 matter that passes across the ' third ventricle 

 Thalamus to the other (figs. 164,9; 157, Th) 



Fig. 164. — Horizontal Section through the Cerpbrum at a 

 deeijer level, showing the Third Ventricle and its Commis- 

 sures and the relations of each Corpus Striatum to the 

 Island of Reil. (Sappey. ) 1, Fornix, together with Velum 

 Interpositum turned backwards in order tx) reveal the Third 

 Ventricle : 2, Veins of Galen ; 3, anterior extremity of the 

 Pineal body ; 4, its superior peduncles ; 5 Posterior Cere- 

 bral Commissure; 6, Anterior Commissure; 7, section of 

 anterior pillars of Fornix ; 8, Third or Middle Ventricle ; 

 9, Grey or Middle Commissure ; 10, Corpus Striatum, the 

 upper and external strata of which have been sliced off; 

 11, Thalamus ; 12, Taenia Semicircularis ; i3, 14, 15, section of 

 Convolutions of the Island of Reil ; 16, section of the intra- 

 ventricular nucleus of the Cori^us Striatum; 17, section of 

 the White Substance of the Hemisphere, at the part which 

 intervenes between the Island of Reil and the upper part of 

 the Cori)us Stri .turn. 



bridge of grey 

 from one 

 and may 



