38 LABORATORY OUTLINE OF NEUROLOGY 



floor and cut the nerve-roots with a slender scalpel or scissors. 

 CareTully free the anterior and ventral surfaces of the olfactory 

 bulb from the lamina cribrosa of the ethmoid bone, cutting off 

 the filaments of the olfactory nerve. Cut out the hypophysis 

 from its cranial pocket in the sella turcica and leave it attached 

 to the brain by the slender infundibulum. The brain may now 

 be lifted out of the cranial cavity and preserved in formalin. 



31. As stated above, most of the dissections described in this 

 Outline can be made on either human or other brains. If brains 

 of the sheep (or dog or cat) are used, specimens and text-book 

 figures of the human brain should be kept constantly at hand for 

 comparison. A certain number of special dissections illus- 

 trating particular features should be made in advance and pre- 

 served permanently. These should be made, if possible, on 

 human brains and should include, among others, three brains 

 sliced respectively in planes parallel with the transverse, frontal, 

 and sagittal planes of the body. Valuable demonstration speci- 

 mens may also be made by following out the directions for dis- 

 secting the several fiber systems given in the "optional dissec- 

 tions" (Sections 102-111 and 141-152), using a separate brain 

 or half brain for each system. 



If only one human brain is available for study, it is advised 

 that it be dissected as directed by Dr. Lineback ('15). By this 

 procedure the brain is first divided in the median plane into right 

 and left halves and one of these halves is then further dissected 

 by a single carefully planned incision so as to remove a con- 

 siderable portion of the cerebral hemisphere from the brain stem 

 and at the same time reveal the internal structure of the hemi- 

 sphere. The method has the further advantage that the three 

 parts into which the brain is cut can readily be reassembled, 

 so that the specimen can still be used for demonstration of the 

 external form in its entirety. 



32. The dissection of many fiber tracts can be carried much 

 farther in well-preserved human brains than is possible in 

 brains of lower animals. Accordingly, there are included in 

 this Outline directions for a certain number of "optional dissec- 

 tions" (Sections 102-111, 141-152), for which human brains 

 well hardened in formalin are necessary. All of the dissections 

 here outlined, except a few of the "optional dissections" can be 



