NERVOUS CENTRES. (HUMAN ANATOMY. THE ENCEPHALON.) 



691 



scribed by Tarin and Malacarne. When the 

 fourth ventricle has been carefully opened in a 

 recent cerebellum, it is very easy to demon- 

 strate them by passing the handle of a knife 

 under them. 



The structure of these lateral wings of the 

 inferior medullary velum is readily ascertained. 

 Their delicacy is such that they admit of being 

 examined by the microscope without pressure 

 or other manipulation. They consist of tubular 

 fibres of various sizes, taking a transverse di- 

 rection, that, namely, of the long diameter of 

 each wing, covered by a layer of nucleus-like 

 particles as an epithelium. They seem to con- 

 nect the nodule to the small lobules of the 

 pneumo-gastric nerve above mentioned (the 

 jftocks of Reil), or to connect those lobules them- 

 selves as a commissure.* 



The nodule pushes before it, into the fourth 

 ventricle, a fold of the pia mater, connected 

 with which on either side are several small 

 granulations, or Pacchionian bodies. It is called 

 the choroid plexus of the fourth ventricle. We 

 can easily trace it to be continuous with the pia 

 mater which covers the lobules of the seventh 

 pair of nerves. 



Next to the nodule, below and behind it, is a 

 small lobe, called by Reil the spigot ( Zupfen), 

 with a pointed extremity directed downwards 

 and forwards. It consists of several small la- 

 mina separated by their fissures. Behind it is 

 a larger lobule, which forms the most prominent 



portion of the inferior vermiform process, called 

 by Reil, from its form, the pyramid. Its apex 

 is directed downwards and backwards, and it 

 likewise consists of numerous small laminae. 



These lobules of the inferior portion of the 

 median lobe serve to connect others of the 

 lateral hemispheres. The spigot connects the 

 almond-like lobes; the pyramid the biventral 

 and the slender lobes. 



Posterior to the pyramid are a series of la- 

 minae which extend to the posterior notch and 

 form its floor. These pass directly from one 

 side to the other, their free margin being con- 

 vex and directed backwards. They connect 

 the posterior inferior lobes. And some of the 

 most anterior of them, which do not project to 

 the surface, connect the slender lobes as well 

 as some of the anterior laminae of the posterior 

 inferior lobes. These latter laminae of the in- 

 ferior vermiform process, Reil distinguishes 

 by the name of long and hidden commissure 

 (Icmgen verdecktcn Commissur), and the former 

 constitute his short and exposed commissure 

 ( Kurzen und sic/itbaren Commissur). 



Above the last-named commissure is a single 

 lamina which forms a line of demarcation be- 

 tween the inferior and the superior vermiform 

 processes, serving to connect the upper and 

 posterior lobes of the hemispheres. This is the 

 single commissure (einfache quer Commissur). 



It will serve to elucidate the foregoing neces- 

 sarily intricate description, if I sum up with 



Fig. 391. 



Inferior surface of the cerebellum. 

 V, inferior vermiform process ; p, posterior pyramids ; r, restiform bodies. 



the following enumeration of the lobes of the the lobes of the superior and inferior vermiform 



hemispheres, specifying at the same time the processes which serve that purpose, 

 commissures by which they are connected, i. e. 1. On the superior surface of the hemispheres. 

 ' Although it does not appear that Reil used the a. The square lobes, consisting of eight 



microscope, his statement respecting the structure lobules, which are connected by as many, or 



of these wings is perfectly correct. nearly so, of the superior vermiform process. 



2 Y 2 



