BASE OF BBAIN,. OPTIC NEEVE, AND COEPOKA QUADEIGEMINA. 389 



Farther dorsal to these are situated tracts that become lost in the latticed 

 layer of the thalamus. 



These relations of the central optic pathway may be plainly recog- 

 nized in a frontal section, passing through the most anterior part of the cor- 

 pora quadrigemina. 



As I have as yet demonstrated no section irom the midbrain region, Fig. 185 — 

 which is an addition to the human brain-sections demonstrated earlier — needs a few 

 words of explanation. 



Faso. oceip.-frout. 

 Nucl. eaudat. 



TLntticed layer ol 

 \ tlialamus 

 Xncl. lentif, 

 fRad. occip.-thal. 

 i (optic tract) 



,Rad. tempoi'O-thal. 



-Nnel. caudatus 

 £:oinm. aat. 

 .Cornu Ammonia 



Fig. 185. — Frontal section through the forebrain and the interbrain near the 

 place where fibers of the eapsula interna become the pes, or crusta, of the ci'us 

 cerebri. 



The ventricle, which farther anteriorly was closed in dorsally by the epithelium 

 of the plexus alone, has narrowed here in the territory of the mesencephalon to the 

 aquseductus Sylvii. Over this the anterior corpora quadrigemina lie like a roof. 

 Since these project, as Fig. 125 shows, somewhat forward between the posterior ends 

 of the thalami, the most posterior, thalamic ganglia — those of the pulvinar — are 

 accordingly cut on each side of the corpora quadrigemina. This division of the 

 thalamus attains its greatest expansion exactly at the plane of this section. Under 



