REMOVAL OF THE BRAIN. 509 



flows backwards in it. The cerebral veins open chiefly at the 

 posterior part of the canal, and they lie for some distance against 

 the wall of the sinus before they perforate the dura mater ; their 

 course is directed from behind forwards, so that the current of the 

 blood in them is opposed to that in the sinus : this disposition of 

 the veins may be seen on the left side of the brain, where the parts 

 are undisturbed. 



DIRECTIONS. Before the rest of the dura mater can be examined, Directions 

 the brain must be taken from the head. To facilitate its removal, JnJS?. 1 

 let the head incline backwards, while the shoulders are raised on a 

 block, so that the brain may be separated somewhat from the base 

 of the skull. For the division of the cranial nerves a sharp scalpel 

 will be necessary ; and the nerves are to be cut longer on the one 

 side than the other. 



Removal of the Brain. As a first step cut across the anterior Mode of 

 part of the falx cerebri, and the different cerebral veins entering the amTparts 8 ' 

 longitudinal sinus; raise and throw backwards the falx, but leave cutinsuc- 

 it uncut behind. Gently lift up the frontal lobes and the olfactory 

 bulbs of the large brain. Next cut through the internal carotid Anterior 

 artery (fig. 189) and the second and third nerves, which then 

 appear, together with some veins descending from the brain ; 

 the large second nerve is placed on the inner, and the round third 

 nerve on the outer side of the artery. 



The brain is now to be supported in the left hand, and the 

 pituitary body to be dislodged with the knife from the hollow in 

 the centre of the sphenoid bone. A strong horizontal process of the next the 

 dura mater (tentorium cerebelli) then comes into view at the back tent| 

 of the cranium. Along its free margin lies the small fourth nerve, 

 which is to be cut at this stage of the proceeding. Make an 

 incision through the tentorium 011 each side, close to its attachment 

 to the temporal bone, without injuring the parts underneath : the 

 following nerves, which will be then visible, are to be divided in 

 succession. Near the inner margin of the tentorium is the fifth posterior 

 nerve, consisting of a large and small root ; while nearer the 

 median plane is the slender sixth nerve. Below the fifth and 

 somewhat external to it, are the seventh and eighth nerves entering 

 the internal auditory meatus, the former being anterior and the 

 smaller of the two. Directly below the foregoing are the ninth, 

 tenth and eleventh nerves in one line : of these the upper small 

 piece is the ninth or the glosso-pharyngeal ; the flat band next 

 below, the tenth or pneumo-gastric ; and the long round nerve 

 ascending from the spinal canal, the eleventh or spinal accessory. 

 The remaining nerve near the median plane is the twelfth, which 

 consists of two small pieces. 



After dividing the nerves, cut through the vertebral arteries as vessels, and 

 they wind round the medulla oblongata. Lastly, cut across the 

 spinal cord as low as possible, as well as the roots of the spinal lastly, the 

 nerves that are attached on each side. Then on placing the first spm< 

 two fingers of the right hand in the spinal canal, the short upper 

 portion of the cord may be raised, and the whole brain may be 



