THE BRAIN. 6$ 



boundary of the part of the fossa now under 

 examination, will be found two nerves : the 

 orbito-nasal or ophthalmic, a branch of the fifth 

 cranial, and the patheticus (fourth cranial) ; the 

 former is the larger. 

 e. Gently removing the bit of Harderian gland, ob- 

 serve the membranous inter-orbital septum, and 

 trace the orbito-nasal nerve forward along it 

 until it enters the nasal chamber. The origin 

 of the superior oblique muscle is above this 

 point of exit, and the fourth nerve may be 

 traced into the muscle near to its origin. 



169. Lying above the inter-orbital septum is a pro- 

 longation of the cranial cavity, covered in by dura 

 mater, and roofed over by bone. On cutting away the 

 bone above, and the dura-mater on the side, the whole 

 of the right side of the brain will be exposed if the 

 original cut were made in the proper plane, passing be- 

 hind through the right margin of the foramen magnum. 

 If the cut has taken a too external direction behind, 

 carefully break the bone away from time to time as may 

 be necessary to observe the parts described below. 



170. On the side of the brain, note : 



a. The right olfactory lobe, reaching in front to the 

 posterior boundary of the nostril and marked 

 off behind by a shallow furrow from — 



b. The right cerebral hemisphere, which is separa- 

 ted behind by a deeper furrow from — 



c. The mid-brain or mesencephalon, behind which 

 comes — 



d. The cerebellum. 



