GUIDE TO THE HEAD AND NECK 1595 



Basal Ganglia of the Cerebral Hemispheres. — The pons Varolii, cerebellum, 

 and medulla oblongata are to be laid aside in the meantime, and the dis- 

 section of what is left of the cerebral hemispheres is to be overtaken. This 

 should be divided into two parts by a mesial, antero-posterior incision, and 

 one of these parts is to be used for the examination of the inferior surface 

 of the cerebral hemisphere. (The mesial surface of the cerebral hemisphere 

 should be studied on another brain.) In this connection the orbital surface 

 of the frontal lobe will fall to be examined, with its olfactory sulcus, triradiate 

 sulcus, and gyri. The inferior surfaces of the temporal and occipital lobes 

 will also admit of being examined. 



The basal ganglia are then to be attended to, these being the nucleus 

 caudatus and nucleus lenticularis of the corpus striatum, the claustrum, and 

 the amygdaloid nucleus. Several sections through the cerebral hemispheres 

 require to be made to obtain a knowledge of these important ganglia. On 

 one side coronal, that is to say, vertical-transverse sections are to be made 

 through the cerebral hemisphere from the level of the front part of the nucleus 

 caudatus backwards to the posterior part of the optic thalamus. On the other 

 side several horizontal sections are to be made through the structures which 

 lie upon the floor of the lateral ventricle. In connection with these sections 

 the dissectors are advised to read the description given of the basal ganglia, 

 and also of the optic thalami, in the text. 



Medulla Oblongata. — The dissectors are to note carefully the superficial 

 origins of the seventh, eighth, ninth, tenth, eleventh, and twelfth cranial 

 nerves. Tke anterior median fissure, with the pyramid on either side, is to 

 be examined, and an effort is to be made to show the decussation of the 

 pjrramids. The olivary body and anterior superficial arcuate fibres are to 

 receive attention. In connection with the posterior area of the medulla 

 oblongata it is to be noted that it is divided into two portions, lower or closed, 

 and upper or open. The lower portion presents in the median line the pos- 

 terior median fissure, on either side of which are the following structures, 

 in order from within outwards: (i) the funiculus gracilis, which is the con- 

 tinuation of Goll's column of the spinal cord, and which terminates superiorly 

 in the clava ; (2) the funiculus cuneatus, or continuation of Burdach's column 

 of the spinal cord, terminating superiorly in the cuneate tubercle ; and {3) the 

 funiculus of Rolando, terminating superiorly in the tubercle of Rolando. The 

 calamus scriptorius, between the two clavae, is to be noted ; but the upper or 

 open part of the medulla had better be postponed until the floor of the fourth 

 ventricle is under consideration. Suffice it to say that it presents on either 

 side the restiform body. The dissectors should at this stage make them- 

 selves familiar with the cistema magna, in connection with the subarachnoid 

 space, this cistema lying between the cerebellum and the medulla oblongata. 

 Further dissection of the medulla oblongata should only be overtaken with 

 proper assistance. 



Pons Varolii. — This will admit of easy examination, except as regards its 

 dorsal surface and internal structure. The points to be noted are as follows : 

 (i) the basilar groove; (2) the crura cerebri, emerging from its upper part ; 

 (3) the middle peduncles, emerging from it laterally ; (4) the stout sensory, 

 and slender motor, roots of the fifth cranial nerve, also emerging from it 

 laterally ; and (5) the sixth, seventh, and eighth cranial nerves at its lower 

 border. The dorsal surface of the pons is to be postponed for a short time, 

 until the floor of the fourth ventricle is under examination. 



Cerebellam. — Like other parts of the encephalon, the cerebellum requires 

 to be examined from several points of view. Assuming, however, that the 

 dissectors desire to get as much as possible out of one brain (a desire to be 

 strongly deprecated) , the component parts of the cerebellum are to be studied. 

 On the superior surface the superior vermis and the upper surface of each 

 hemisphere are to be examined. On the under surface the vallecula is to be 

 noted, with the inferior vermis lying deeply in it. In connection with the 

 inferior vermis the following parts are to be studied: (i) the tuber valvulze ; 

 (2) the pyramid ; {3) the uvula, with the furrowed band on either side of it, 

 covered by the amygdala ; and (4) the nodule, with the lateral portion of the 

 inferior medullary velum on either side of it. On the under surface of each 



