CHAPTER X. 

 DISSECTION OF THE BRAIN. 



SECTION I. 



MEMBRANES AND VESSELS. 



DIRECTIONS. The workers on the head and neck examine the 

 brain together, and it is most desirable that, at the time of its 

 removal from the head, they should obtain a second specimen, so that A second 

 the minor cutting operations should be performed on one and the desirable, 

 other left in its entirety till the study of the cerebral hemispheres is 

 commenced. Notwithstanding this, however, the directions for 

 dissection are given as far as possible so that one specimen should 

 suffice. Both brains will be preserved according to the subjoined 

 instructions. 



Preservation and dissection. After the removal of the brain 

 with its divesting membranes as directed on pp. 509 el seq, it should be 

 thoroughly washed free of blood and then placed, with its under 

 surface upwards, in a good-sized earthenware jar provided with a 

 well-titling cover. The brain should rest on a large, loose, pad of 

 tow or cotton wool spread over the bottom of the jar, and the vessel Preserve iu 

 should contain a 5 per cent, solution of formalin in water in sufficient 

 quantities to cover the brain with a clear inch of liquid. The 

 membranes and vessels, as described in this Section, should be 

 examined as soon as possible after the specimen has been in the 

 preservative for two days ; for the reason that they are more easily 

 traced whilst the preparation is still moderately soft, and that they 

 can then be more readily removed without injury to the brain 

 substance ; moreover, it is necessary to remove them at an early stage 

 in order to give the hardening fluid free access. 



When the preparation is removed from the jar for the examination 

 of the membranes and vessels, it should be well washed in running 

 water to remove the adhering formalin solution, which is apt to be 

 inconvenient to the dissector by the lachrymation it causes. 



In describing the distribution of the blood vessels it is unavoidable 

 to refer to various parts of the brain that have not yet been examined 

 in detail, and it i.s therefore desirable that the student should have at 

 hand a museum preparation in which the convolutions and sulci are 

 clearly defined and marked (see fig. 270, p. 746, and fig. 273, p. 753). 



