HEAD AND NECK OF THE HORSE 



185 



fissure is the hippocampal gyrus, continuous below with the piriform 

 lobe. 



Bhinencephalon. — A considerable number of structures are usually 

 included under this term. They are: — Olfactory lobe, substantia 

 perforata anterior, piriform lobe, gyrus fornicatus, subcallosal and supra- 

 callosal gyri, fascia dentata, fornix, septum pellucidum, hippocampus, 

 cingulum, mamuiillary body, fasciculus thalamomammillaris, and a part 

 of the anterior commissure. Many of these are examined in connection 



Splenium of corpus callosum. 



Choroid plexus. 



Cruciate sulcus. 



Aqueduct (S 



Fourth ventricle. 

 Medulla oblongata. 

 Anterior medullary velum. 



rpus callosum. 



^ Intermediate mass. 



Genu of corpus 

 callosum. 



Olfactory bulb. 



Olfactory tract. 

 Rostrum of corpus callosum. 



Pons. / 



Cerebral peduncle. / 

 N. oculomotorius. 

 Mammillarv bod 



\ \ 

 \ 



\ Area parolfactoria. 



Anterior commissure. 



Optic chiasma. 



/ / / 



/ I 



Hypophysis. / / 



Third ventricle. ' / 

 Lamina terminalis. 



Fig. 86.— Median longitudinal section of the brain. 



with other parts of the brain, but others may be fittingly considered at 

 this stage of the dissection. 



The olfactory lohe (lobus olfactorius) consists of the olfactory bulb, 

 tract, stria; and trigone, and a parolfactory area. The olfactory hulh 

 (bulbus olfactorius) is a flattened oval body placed against the frontal 

 pole of the cerebral hemisphere, and, when the brain is in the cranium, 

 fitted to the deep fossa of the ethmoid bone. Its convex surface re- 

 ceives the numerous olfactory nerves that pierce the foramina of the 

 cribriform plate of the ethmoid. From the posterior part of the bulb a 

 short, broad, white band, the olfactory tract (tractus olfactorius) passes 



