THE CEREBELLUM did 
are separated from the vermis by two deep paramedian fissures. They lie in the 
lateral depressions of the cerebellar compartment of the cranium. 
In tracing the fissures from behind forward it will be noticed that they are nearly sagittal 
as far as the anterior surface, where they diverge widely, so that the vermis forms all of the fore 
part of the cerebellum. 
The surface of the cerebellum is further cut up into numerous gyri (cerebelli) 
by narrow and relatively deep sulci (cerebelli), many of which approach a trans- 
verse direction. Certain of the sulci are more pronounced than the others, and by 
means of them it is possible to define groups of gyri. Such groups are termed 
lobes, and have received specific names, derived chiefly from the systematic de- 
scriptions of the human cerebellum. 
The lobes of the vermis are readily distinguished on median section. Enumerated from 
the anterior to the posterior extremity they are: (1) lingula, (2) lobus centralis, (3) lobus ascendens, 
(4) lobus culminis, (5) lobus clivi, (6) tuber vermis, (7) pyramis, (8) uvula, (9) nodulus. Each 
hemisphere is cut into laterally by two sulci which mark off two sagittal discoid masses, termed by 
Ziehen tabulations. The lateral tabulation consists of four or five lobules, the lowest of which 
is regarded as the flocculus. The medial part of the hemisphere is divided into three or four lobes. 
Martin proposes the term tractus for the sagittal masses; on this basis the vermis would become 
the tractus medianus, and the others tractus laterales (primus, secundus, etc.). In the absence 
of a satisfactory morphological basis it seems undesirable to deal with the lobation of the cere- 
bellum in further detail. 
The cerebellar peduncles (Pedunculi cerebelli), three on each side, join the 
central white matter of the cerebellum at the base. The posterior peduncle is the 
restiform body of the medulla, a large rounded tract derived from the lateral and 
ventral columns of the cord. Near the middle of the medulla it inclines outward, 
forms the lateral wall of the fourth ventricle, and ends by entering the central white 
matter of the cerebellum. The middle peduncle is formed, as previously seen, by 
the brachium pontis. The anterior peduncles (Brachia conjunctiva) pass forward 
on either side on the dorsal surface of the pons, forming the lateral boundary of the 
fore part of the fourth ventricle. They disappear under the corpora quadrigemina 
into the substance of the mid-brain. At the point of disappearance the trochlear 
(fourth) nerve emerges from the mid-brain. In some cases two or three bundles of 
fibers (Fila lateralia pontis) arise in the angle between the middle and anterior 
peduncle, curve obliquely forward and downward over the outer aspect of the 
latter, and spread out on the ventral face of the cerebral peduncle just in front of 
the pons. 
On sagittal section the cerebellum is seen to consist of a layer of gray cortical 
substance (Substantia corticalis) and the white medullary substance. The white 
matter consists of a large basal mass (Corpus medullare), which is joined by the 
peduncles and gives off primary lamine (Laminew medullares) to the lobules; 
from these secondary and tertiary lamin arise, the latter entering the gyri. The 
arrangement on sagittal section is tree-like, hence the term “arbor medullaris,” 
which is applied to it.1| The central gray matter consists of groups of cells which 
form small nuclei embedded in the central white substance. 
The principal connections established by the peduncular fibers of the cerebellum are as 
follows: The posterior peduncle (Corpus restiforme) is composed of afferent and efferent fibers 
which connect the cerebellum with the medulla and spinal cord. The cerebello-spinal fascicu- 
lus or direct cerebellar tract, which arises from the cells of the nucleus dorsalis (Clarke’s column) 
of the cord, ends in the cortex of the vermis; many of its fibers cross to the opposite side. Nu- 
merous arcuate fibers from the nucleus gracilis and nucleus cuneatus of the same and opposite 
sides establish connections with cells of the cerebellar cortex. Olivo-cerebellar fibers (chiefly 
afferent) connect with the olivary nucleus of the same and of the opposite side of the medulla 
oblongata. The nucleo-cerebellar fasciculus comprises fibers derived from the nuclei of the 
fifth, eighth, and tenth cranial nerves (Edinger). The descending cerebello-spinal fasciculus 
consists of fibers which terminate in relation with cells of the ventral horns of the spinal cord. 
The chief facts concerning the middle peduncle have been mentioned in the description of the 
pons. The anterior peduncle is essentially an efferent tract, the fibers of which pass forward 
1 Also known as the “arbor vite.” 
