Cerebellum Anatomy

1. Cerebellum
Dr Muhammad Arshad
CIMS Multan

2. Learning Objectives
• At the end of demonstration, the student will
be able to:
• Describe the gross features of cerebellum
• Enumerate the deep nuclei and connections
• Describe the subdivisions of cerebellum
• Describe the cerebellar peduncles
• Explain the anatomical basis of clinical
features of cerebellar diseases

3. Introduction
• Develops from alar plates (rhombic lips) of the
metencephalon
• Cerebellum lies in posterior cranial fossa
behind pons and medulla oblongata
• Separated from pons and medulla by 4th
ventrical
• Weight: 150 gram

4. Introduction
• Cerebellum is separated from cerebrum by
tentorium cerebelli
• Its surface is marked by folia and fissures
• Cerebellum consists of two hemispheres
united in midline by the vermis
• Each hemisphere is connected to three parts
of brainstem by three pairs of fibers called
cerebellar peduncles

8. Functions
• The basic functions of cerebellum are
• 1. Maintenance of equilibrium
• 2. Regulation of muscle tone and learning of
repeated motor functions
• 3. Coordination of voluntary motor activity

9. Introduction
• Cerebellar disease is manifested by motor
disturbances, including staggering gait,
hypotonia , failure of coordination
• Note:- There is no paralysis or inability to
start or stop movement by cerebellar lesion

10. Major subdivisions of cerebellum
• Consists of a midline vermis and two lateral
hemisphere
• Covered by outer three-layered cortex, which
contains folia and fissures
• Contains a central medullay core, wich is the
white mater that contains myeliated axons
• And four cerebellar nuclei (dentate,
emboliform, globose and fastigeal nuclei)

12. Major subdivisions
• Interposed nucleus=(emboliform+globose
nuclei)

13. Nuclear connections of cerebellum

15. External Features
• Three parts: A part lying near the midline is
called vermis and two lateral hemispheres.
Two surfaces, three well marked fissures,
two notches.

16. External Features
• Surfaces: Superior and Inferior; Superior
surface is convex , no line of distinction
between vermis and hemispheres
• Inferior surface: on this aspect, two
hemispheres are separated by a deep
depression called vallecua. The vermis lies in
depth of this depression

17. Notches
• The anterior aspect of cerebellum is marked
by a wide shallow anterior cerebellar notch
which accommodates pons and medulla
• The posterior cerebellar notch is deep and
narrow, and lodges the falx cereblli

18. Fissures and Lobes
• The surface of cerebellum is marked by series
of fissures transversely.
• Some of the fissures are deeper than others.
They divide the cerebellum into lobes within
which smaller lobules may be recognized
• V-shaped Fissura prima running transveresly
across the superior surface

19. Fissures
• Posterolateral fissure seen on inferior surface
and separates flocculonodular lobe from rest
of cerebellum
• The horizontal fissure is most conspicuous
and runs along the lateral and posterior
margins of cerebellum
• It divides cerebellum into superior and
inferior surfaces

20. Lobes of cerebellum
Lobes:
• 1. The part anterior to primary fissure is
anterior lobe. (spinocerebellum) receives
inputs from muscle spindles and golgi tendon
organs via spinocerebellar tracts
• Play a role in regulation of muscle tone
• 2. Paleocerebellum consists of anterior(except
lingula)+pyramid+uvula of posterior lob

21. Lobes of cerebellum
• The part between primary and posterolateral
fissures is posterior (middle) lobe receives
input from neocortex via
corticopontocerebellar fibers
• Plays a role in coordination of voluntary motor
activity
• 3. Neocerebellum consists of posterior lobe
except pyramid and uvula

22. Flocculonodular lobe
• 4. Flocculonodular lobe
(vestibulocerebellum) is smallest of all and
lies on inferior surface in front of
posterolateral fissure
• Receives input from the vestibular system
• Plays a role in the maintenance of posture and
balance

23. Vermis
• Proceeding from above downwards, it consists
of the lingula, central lobule, and culman,(in
the anterior lobe); the declive, pyramid and
uvula (in the middle lobe); and the nodule (in
the flocculonodular lobe)

26. Subdivisions (lobules)

29. Internal structure
• Cerebellum is made up of a thin layer of grey
mater, cerebellar cortex and intracerebellar
nuclei
• A central core of white mater being arranged
in the form of branching pattern of a tree, is
called arbor vitae= tree of life
• The cerebellar cortex has a uniform srtucture
in all parts of cerebellum

30. Structure of cerebellar cortex
• It consists of three distinct layers with five
neurons:
• 1. Outer Molecular layer (outer Stellate
cells+Basket cells)
• 2. Intermediate Purkinje cell layer (Purkinje
cells)
• 3. Inner Granular layer (Granule cells+Golgi
cells )

32. Cerebellar cortex

33. Intracerebellar nuclei
• Embedded in the central core of white mater,
there are masses of grey mater which
constitute the cerebellar nuclei
• From lateral to medial these are
• 1. Dentate nucleus
• 2. Emboliform nucleus
• 3. Globose nucleus
• 4. Fastigial nucleus

34. Afferent fibers entering cerebellar
cortex
• Two different types:
• Mossy fibers: All fibers(excitatory) entering
cerebellum, other than olivocerebellar, end as
mossy fibers.
• These fibers originate from vestibular nuclei
(vestibulocerebellar), pontine nuclei
(pontocerebellar) and spinal cord
(spinocerebellar)

35. Cerebellar cortex layers,fibers and cells

36. Afferent fibers
• These fibers terminate in granular layer of
cortex within the glomeruli and excite granule
cells.
• Climbing fibers: Afferent excitatory fibers of
the olivocerebellar tract
• Terminate on dendrites of purkinje cells

37. Efferent fibers
• These are axons of Purkinje cells which
terminate in the cerebellar nuclei.
• These are inhibitory to cerebellar nuclei

38. Cerebellar Peduncles
• Superior -→ Midbrain ║Brain
• Middle - →Pons ║ Stem
• Inferior – →Medulla oblongata║

39. Fibers in cerebellar Peduncles
Superior Cerebellar
peduncle
Afferent Efferent
Mainly efferent Anterior spinocerebellar
Tectocerebellar
Cerebello-rubral
Dentato-thalamic
Dentato-olivary
Fastigio-reticular
Middle Cerebellar
peduncle
Only afferent
Cortico-ponto-cerebellar

40. Fibers in cerebellar peduncles
Inferior Cerebellar
peduncle
Mainly afferent
Afferent Efferent
Posterior spinocerebellar Cerebello-vestibular
Cuneo-cerebellar
(posterior external arcuate
fibers)
Cerebello-olivary
Olivo-cerebellar Cerebello-reticular
Para-olivo-cerebellar
Reticulo-cerebellar
Vestibulo-cerebellar
Anterior external arcuate
fibers
Stria Medullaris
Trigemino-cerebellar

41. Clinical correlation
• Hypotonia
• Disequilibrium
• Dyssynergia includes
• 1. Dysarthria
• 2. Dystaxia
• 3. Intention tremors
• 4. dysmetria (past-pointing)

42. Clinical correlation
• 5. Dysdiadochokinesia
• 6. Nystagmus
• 7. Asthenia
• Tumors of the cerebellam
• Astrocytomas
• Medduloblastomas
• Ependymomas

43. Clinical correlation

44. Clinical correlation