THE CERKHKLU'M 



7! U 



these bands its folia curve and become continuous with the tonsils. The uvula and 

 the two tonsils arc sometimes referred to collectively as the uvular lulu . 



I. The nodule is l lie smallest and most anterior division of t lie inferior vermis. 

 It is separated Iroin the uvula by the post-nodular fissure, and is closely associated 

 anteriorly with the posterior medullary velum, the transverse continuation of the 

 peduncles of the lloccuiar lobes. 



Internal structure of the cerebellum. The white substance of the cerebellum 

 is continuous with its peduncles and forms a compact central mass. Over the sur- 

 face of this the grey substance or cortex is spread in a thin but uniform layer. I'pon 

 section of the cerebellum <-,-rtain of the sulci as well as the fissures are shown to be 

 much deeper than is apparent from the surface. The deeper sulci separate the lobes 

 into divisions, the medullary laminae, each of which is composed of a number of 

 folia and each of which has its own core of white substance. The folia of the lamina- 

 line the sulci (and fissures), and also comprise their surface aspect, and are separated 

 by the shallow, secondary sulci. The larger lamina' are subdivided into from two 

 to four secondary lamina; of varying size. Such subdivision is especially marked 

 in the vermis. Here each lamina comprises a lobule and is, therefore, separated by 



FIG. 587. DIAGRAM OF THE VENTRAL AND INFERIOR SURFACE OF THE CEREBELLUM AFTER THE 



REMOVAL OF THE MEDULLA OBLONGATA, PONS, AND MESENCEPHALON. 

 The tonsil of the right side is omitted in order to display the connection of the pyramid 

 with the biventral lobe, the furrowed band of the uvula, and more fully the posterior medullary 

 velum. The anterior notch is less evident than in the actual specimen. 



SVPKHlnl; CESEBEL- 



LAK I'l'.tn NCI r 



POST l-:l: Kilt M/:'l>l'l.- 



LAI1Y I'/.Y ' M 



MIDDLE ( -Jill /;/.' /:/. / I /.' 



PEDUNCLE 



FLOCCCl.r* - 



sir EX /'/.'. i/. 



LOBE 

 LOBfl.rs 



/,/: HY/./.N 

 ANTERIOR 



LOBULUS 



<;/;. it'll /x 



ANTERIOR 



Mi-:nri.LAKY 



rA\V //.-/' l.K VELUM L1NOVLA 



MODULI-: 



UVULA 



SEMI 1.1'* Ml 

 LUBE 



TONSIL 



TUBER VERMIS 



PYRAMID 

 POSTERIOR CEREBELLAR NOTCH 



a fissure, and each lobule is usually subdivided with the exception of the nodule, the 

 folium, and the lingula. In sagittal sections, or sections transverse to the general 

 direction of the sulci, this arrangement of the laminae gives a foliate appearance, 

 which, especially in sagittal sections of the vermis, is termed the 'arbor vitae.' 



The cerebellar cortex consists of three layers and contains four general types of cell-bodies 

 of neurones, all of which possess features peculiar to the cerebellum. 



The outermost or molecular layer contains small stellate cells with relatively long den- 

 drites. These serve to associate the different portions of a given folium. The axones of the largest 

 of them give off branches which form pericellular baskets about the bodies of the cell* o/ Pur- 

 kinje. each axonc contributing to several baskets. The layer of Purkinje cells, or the middle 

 layer, is .pule thin. The bodies of the cells of Purkinje are arranged in a single layer, and their 

 elaborate systems of dcndrites extend throughout and largely compose the molecular layer. 

 The dendrites of these, the most essential cells of the cortex, arc displayed in the form of 

 arborescent tans (gee litr. .Vi.'i >, arranged parallel with each other and transverse to the long axis of 

 the folium containing them. Their axones are given off from the base of the cell-body, acquire 

 their medullary sheaths i|uite close to the cell-body, and, after giving off several collaterals in 

 the inner layer, pass into the general white substance and thence to other lamina- or lobes and 

 certain of them to structures outside the cerebellum. The inner layer is the granular layer. 

 It contains numerous small nerve-cells or er.-mule-cells which possess from two to five radiating 

 dendrites, unhranched except at their termination, which occurs suddenly- in the form of three 

 to six claw-like twigs. Their axones are given off either from the cell-body direct or more often 



