EXPOSURE OF MOTOR AREAS 



105 



one-half or three-fourths inch from the median line make 

 an opening through the skull. (It may be necessary later 

 to enlarge this opening.) Be sure to keep far enough out 

 from the median line to avoid the great longitudinal sinus 

 inside the skull (8). (If this is opened accidentally quickly 



Fig. 100. Trephine. 



remove the trephine instrument and tightly plug the open- 

 ing with cotton to stop the hemorrhage. Then turn the 

 animal over and perform the operation on the left side.) 

 Remove the button of bone and the dura mater over the 



