1398 



A MANUAL OF ANATOMY 



Rhinencephalon. — The rhinencephalon consists of the olfactory lobe, uncus, 

 gyrus dentatus, supracallosal and subcallosal gyri, half of the septum lucidum, 

 half of the fornix, and hippocampus major. 



Development of the Olfactory Organ. 



The olfactory organ is developed in two parts — the olfactory lobe, and the 

 olfactory epithelium. The olfactory lobe is intracranial, and is an outgrowth 

 from the anterior part of the ventral aspect or floor of the telencephalon, 



Great Longitudiaai Fissure 



Forceps Minor ^ 



Genu of Corpus Callosum 



".Median Raph^ 



Stria 



. Longitudinalis 



Mesialis 



Stria 

 „ Longitudinalis 

 I^ateralis 



Tapetuni 



Forceps Majof 



Great Longitudinal Fissure 



Splenium of Corpus 

 Callosum 



Fig. 588. — The Corpus Callosum (Superior View) (Hirschfeld 



AND LEVEILLfe). 



which is the cephalic division of the prosencephalon, or fore-brain. It consti- 

 tutes the olfactory lobe (rhinencephalon) of the brain, and it becomes trans- 

 formed into several parts, which will presently be stated, its terminal portion 

 being the olfactory bulb, which rests upon one-half of the cribriform plate 

 of the ethmoid bone. 



The olfactory epithelium is intranasal, and occupies the upper part of the 

 nasal fossa of either side. It represents a neuro-cpithelium, which is derived 

 from an invagination of the surface-ectoderm. The axons of its sensory 

 cells constitute the olfactory nerve-filaments, which pass upwards through the 

 foramina of the cribriform plate, and enter the under surface of the olfactory 

 bulb. 



