186 



TOPOGRAPHICAL ANATOMY OF THE 



backwards on the ventral aspect of the hemisphere, and divides into the 

 two olfactory strice (strias olfactorii). The lateral stria is much the 

 more distinct, and runs in a lateral, dorsal and backward direction 

 forming the medial lip of the rhinal fissure. Posteriorly it is lost in the 

 piriform lobe. The much less definite and shorter medial stria curves 

 towards the middle line, and disappears into the longitudinal fissure 

 between the two hemispheres. 



Longitudinal fissure. 



Rhinal fissure. 



Optic chiasma. 

 Optic tract 



1st cervical nerve 



Olfactorv bulb 



Olfactory tract. 



^— ^-Olfactory stria. 



-Olfactory triarone. 



Infundibulum. 

 Piriform lobe. 



Mammillary body. 

 Cerebral peduncle. 

 Interpeduncular fossa. 

 Pons. 



Corpus trai>ezoideum. 



^^•^♦^ij Cerebellum. 



J f'AJirf Choroid plexus. 



3-j^^Zr Pyramid. 



\'entral median fissure. 



Decussation of pyramids. 



Fig. 87. — Ventral aspect of the brain. 



The olfactory bulb contains a cavity of some size, which is connected 

 with the anterior cornu of the lateral ventricle by a narrow canal that 

 traverses the olfactory tract. 



The olfactory trigone (trigonum olfactorium) is an elevated grey 

 area between the olfactory striae It is continuous with an ill-defined 

 area (area parol factoria) on the medial surface of the hemisphere. 



The piriform lobe (lobus piriformis) forms a conspicuous pear-shaped 

 elevation, indented by one or two shallow grooves, immediately lateral to 



