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Gross Anatomy of the Cerebellum
By
Prof. Dr. Muhammad Imran Qureshi
Normal Functions
 Coordination
 Balance
 Posture
 Eye movements
 Motor learning
Introduction
It is known as the Little Brain and constitutes 11% of the total brain mass. In the
posterior cranial fossa, it lies dorsal to
pons and medulla oblongata, from which it
is separated by the cavity of the fourth
ventricle.
The occipital lobe of the cerebral
hemisphere lies above it. The two are
separated by a fold of dura mater called
the tentorium cerebelli.
Part of the cavity of the fourth ventricle
extends into it as a transverse cleft,
which is bounded cranially by a lamina of
white mater called the Superior
Medullary Velum.
Architecture
It has a superficial layer of gray mater,
while the white mater lies deeply.
Discrete masses of Gray mater are
present in the central region of the
cerebellum in the form of FOUR nuclei.
The cerebellum consists of TWO lateral
hemispheres, separated by a central zone
called the Vermis. It has Two surfaces,
the Superior, and the Inferior.
On the superior surface, there is no line of demarcation between the vermis and
the hemispheres. However, on the inferior surface, the two hemispheres are well
demarcated from one another by a deep depression, called the Vallecula Cerebelli.
The Vermis lies in the depth of the Vallecula. Here, the vermis is separated from
each cerebellar
hemisphere by a
Paramedian sulcus.
Anteriorly and
posteriorly, the
hemispheres extend
beyond the vermis
and are separated
by anterior and
posterior cerebellar
notches.
The falx cerebelli
lies in the posterior
cerebellar notch.
The surface of cerebellum is marked by a series of fissures that run almost
parallel to one another. These fissures subdivide the cerebellum into narrow leaf
like bands, called the Folia. The
long axis of the majority of
folia is transverse.
The outer rind of each folium is
made up of Grey mater, while
within it runs a very thin core
of white mater.A section cut at
right angle to the folium gives
it a characteristic Tree like
appearance and is called Arbor
Vitae (Tree of Life)
Fissures and Lobes
Some of the fissures on the surface of the cerebellum are deeper than the others
and are named. These fissures divide the cerebellum into lobes.
Thus the Primary fissure (Fissura Prima), which separates it into a smaller
anterior and a larger posterior lobes, runs transversely on the superior surface.
Another fissure, called the Posterolateral fissure is present on the inferior aspect
and separates the Posterior lobe from the Flocculonodular lobe.
The anterior and posterior lobes together form the Corpus Cerebelli.
Another fissure, called the Horizontal fissure divides the cerebellum into upper
and lower halves. Thus the part above this fissure is the superior surface and the
part below it is the inferior surface.
Within the corpus cerebelli, other less deep (un named) fissures divide each lobe
into lobules.
To see various divisions of the cerebellum in a single view, the cerebellum is
represented as if it has been opened out, so that the superior and inferior
surfaces are visible together. From above downwards, different parts of the
vermis are:
Lingula
Central Lobule
Culmen
Declive
Folium
Tuber
Pyramis
Uvula
Nodule
Parts of Hemispheres
With the exception of lingula,
each subdivision of the vermis is
related laterally to a part of the hemisphere.
Thus Central lobule is related to the Ala of central lobule.
Culmen to Anterior quadrangular lobule
Declive to Posterior quadrangular lobule
Folium to Superior semilunar lobule
Tuber to Inferior semilunar lobule
Pyramis to Biventral lobule
Uvula to tonsil, and
Nodule to Flocculus
Phylogeny
On the basis of Phylogeny, THREE divisions of the cerebellum are recognized:
The Archycerebellum, which is the only component of cerebellum in the fishes and
lower amphibians. It consists of the flocculonodular lobe and the lingula.
The Paleocerebellum makes its first appearance in higher amphibians and is larger
in reptiles and birds. In the human, it is represented by the superior vermis in the
anterior lobe and part of the inferior vermis in the posterior lobe
The cerebellar hemispheres together with the superior vermis in the posterior
lobe constitute the Neocerebellum, which is found in mammals and is largest in the
humans
Functional Divisions
These phylogenetic divisions correspond largely with the divisions based on major
sources of afferent fibers. Thus:
The archycerebellum is identical to the Vestibulocerebellum, which receives input
from the vestibular nerve and nuclei
Those parts of the vermis that constitute the paleocerebellum, together with
adjacent parts of the hemispheres (that belong to neocerebellum) make up the
Spinocerebellum. This is the site of termination of the spinocerebellar tracts and
cuneocerebellar fibers, which convey proprioceptive and other sensory information.
The remainder of the neocerebellum (i.e. the large lateral parts of the
hemispheres, and the superior vermis in the posterior lobe) constitute the
pontocerebellum. The contralateral pontine nuclei send afferent fibers to this
area. Some overlapping occurs in these divisions
Grey matter of the Cerebellum
Most of the grey matter of the cerebellum is arranged as a thin layer covering the
central core of the white mater---- Cerebellar cortex. Unlike the Cerebral Grey
matter, it is uniform throughout.
Embedded within the central core of white mater are masses of grey matter called
the cerebellar nuclei. These are, from medial to lateral side:
 Fastigeal Nucleus
 Globose Nucleus
 Emboliform Nucleus,
 Dentate Nucleus
Mnemonic: Fat Goat Eats Dandelion
Cerebellar Peduncles
Superior Cerebellar Peduncle:
Connects the cerebellum to Mid brain
Middle Cerebellar Peduncle:
Connects the cerebellum to the Pons
Inferior Cerebellar Peduncle:
Connects the cerebellum to The Medulla and Spinal cord
Regulation of
muscle tone,
coordination of
skilled voluntary
movement
Planning and
initiation of
voluntary activity
Maintenance of
balance, control
of eye movements
Vestibulocerebellum
Spinocerebellum
Cerebrocerebelum