for MBBS students

1. THE CEREBELLUM

2. INTRODUCTION

3. Smallest in size while largest part of the
hindbrain.
Its control is IPSILATERAL.
Homotypical
Important functions are to maintaining
tone, posture and equilibrium of the body
It is the in adults the weight ratio of
cerebellum to cerebrum is approximately
1 : 10 and in infants 1 : 20.
 CEREBELLUM: latin SMALL BRAIN

4. Weight is approx 150 gm in an adult.
ie. About 10% of the weight of the cereberal
hemisphere
 cerebellar cortex has about 50% of surface area
of the cerebral cortex
 The cerebellum lies dorsal to the pons and medulla,
from which it is separated by the fourth ventricle.
 It is seperated from the cerebrum by TENTORIUM
CEREBELLI.

5. Millions of neurons compact to form “ARBOR
VITAE=vital tree of life”

6. LOCATION

7. • Lies above and behind the medulla and pons and
occupies posterior cranial fossa.
• RELATION-
• Anteriorly –
fourth ventricle,
pons and medulla
• Posteroinferiorly –
occipital bone
• Superiorly –
tentorium cerebelli

8. EXTERNAL
FEATURES

10. LOBES
•Two deep fissures
•Primary fissure
•Posterolateral fissure
•Three lobs
•Flocculonodular lobe
(flocculus and nodule)
•Anterior lobe
•Posterior lobe
Corpus of
cerebellar

11. Primary fissure
Posterolateral fissure
Flocculonodular lobe
Anterior lobe
Posterior lobe
corpus of
cerebellar

12. Subdivisions of the vermis of the cerebellum
as seen in a median section

15. PHYLOGENITIC DIVISION
ARCHICEREBELLUM
NEOCEREBELLUM
PALEOCEREBELLUM

16. PHYLOGENETIC
DIVISION
ANATOMICAL
COMPONENT
CHIEF
CONNECTION
FUNCTION FUNCTIONAL
CLASSIFICATION
ARCHICEREBEL
LUM
FLOCCULONOD
ULAR LOBE
AND LINGULA
VESTIBULAR
APPERATUS
BODY
EQUILIBRIUM
Vestibulocereb
ellum
PALEOCEREBEL
LUM
ANTERIOR
LOBE (EXCEPT
LINGULA),PYRA
MID AND
UVULA
SPINAL CORD MUSCLE
TONE,CRUDE
MOVEMENTS
Spinocerebellu
m
NEOCEREBELLU
M
POSTERIOR
LOBE (EXCEPT
PYRAAMID
AAND UVULA)
PONS CO-
ORDINATION
OF BODY
MOVEMENTS
Cerebrocerebe
llum

17. ANTERIOR AND
POSTERIOR LOBE IS
MAINLY DEVIDED INTO 3
PARTS THESE ARE;
(a)LATERAL ZONE
(b)INTERMEDIATE ZONE
(c)VERMIS ZONE
Functional regions of cerebellum

18. INTERNAL STRUCTURES
Gray matter
• Cerebellar cortex
• Cerebellar nuclei
• Dentate nucleus
• Fastigial nucleus
• Interposed nucleus
• Emboliform nucleus
• Globose nucleus
White matter－medullary
center

19. Cerebellar cortex
Dentate nucleus
Fastigial nucleus
Globose nucleus
Emboliform nucleus
medullary center

20. The white matter consists of:
(a) Afferent fibres entering the cerebellum from
outside.
(b) Projection fibres from the cerebellar cortex
to the cerebellar nuclei.
(c) Association fibres interconnecting different
parts of the cerebellar cortex.
(d) Commissural fibres connecting the two
cerebellar hemispheres.
(e) Fibres from the cerebellar nuclei (and some
from the cerebellar cortex) to centres outside
the cerebellum.

21. 1. Stellate Cells –(inhibitory).
Star shaped
 contact Purkinje cell dendrites
location: outer molecular layer
Cell Types:

22. 2. Basket Cells –(inhibitory, GABA)
 contact Purkinje soma (“basket” around it)
 Each basket cell may synapse with 70 purkinje
fibres.
 inhibitory to purkinje cells.
 location: inner molecular layer

23. 3.Purkinje (inhibitory – GABA)
characteristic cell of cerebellum
Flasked shaped cell bodies
Dendrites arise from neck
of the flask.
Axon moves downward
Through the granular layer
To enter the white matter.
Their end synapse with
Neurons in cerebellar nuclei.
INHIBITYORY in nature.

24. 4. Granule cell
Very small , numerous,
spherical neurons
Occupy the greater part of
granular layer.
Having 3-5 dendrites
Claw like endigs,
 contacted by mossy fibres.
 the only excitatory neuron.
The spaces not occupied
by these cells in the
granular layer are called
cerebellar islands

25. 5. Golgi Cells –(inhibitory, GABA).
 contacts granule cell within “glomeruli”
(inhibitory) –
 glial capsule and specificity of connections.
 location: granule cell layer

26. Complex synapsis
structure
About 10 um in
diameter
Surrounded by
neuroglial cell
STRUCTURE OF GLOMERULI
These synapse are
axodendritic and
excitatory

27. Core is formed by expandaded
terminartion of mossy fibre
Termination is also called ROSETTE
Also receive synapse with granule and
golgi cell

28. Neurons in the Cerebellar Cortex Are
Organized into Three Layers

31. Histologically afferents fibres are of two
distinct types.
(a) Mossy fibres:
 Excitatory fibre
These fibres terminate in the granular
layer of the cortex, within glomeruli.
They branch profusely within the granular
layer, each branch ending in an expanded
terminal called a rosette
All fibres entering the cerebellum,
afferent inputs; mossy fibres pass
through granule cells to reach Purkinje cells.

32. (b) Climbing fibres:
Excitatory fibre
olivo-cerebellar fibres end predominantly as
climbing fibres
 terminations of axons reaching the cerebellum
from the inferior olivary complex
 They pass through the granular layer, and the
Purkinje cell layer, to reach the
molecular layer.
 climbing fibres as they appear to climb up
along the Purkinje cell dendrites

33. CONNECTIONS OF CEREBELLUM
Inferior cerebellar
peduncle－
also called the restiform body
connect posterolateral part of
the medulla with spinal cord,
 contain both afferent and
efferent fibers,,
Peduncles: Three peduncles

34. Middle cerebellar peduncle -
connect with pons,
contain afferent fibers
Its fibres, which arise in pontine nuclei, cross to
the opposite side
Superior cerebellar peduncle －
•connect with midbrain,
•contain mostly efferent fibers
consists mainly of fibres arising in cerebellar nuclei
(mainly the dentate nucleus)
•The right and left peduncles are connected by a
thin lamina of white matter, the superior (or
anterior) medullary velum

37. Ventral spino-cerebellar
tract
Cerebello-rubral fibres
Tecto-cerebellar fibres Cerebello-thalamic fibres
Trigemino-cerebellar fibres Cerebello-reticular fibres
Hypothalamo-cerebellar fibres Cerebello-olivary fibres
Coerulo-cerebellar fibres. cerebellohyprthalamic
SUPERIOR CEREBELLAR PEDUNCLE
AFFERENT EFFERENT
MIDDLE CEREBELLAR PEDUNCLE
ponto-cerebellar fibres.
serotoninergic fibres

38. Posterior spino-cerebellar tract
Cuneo-cerebellar tract (posterior external
arcuate fibres).
Olivo-cerebellar fibres
Reticulo-cerebellar fibres
Vestibulo-cerebellar fibres
Anterior external arcuate fibres
Fibres of striae medullares
Trigemino-cerebellar fibres
Cerebello-olivary fibres.
Cerebello-vestibular fibres
Cerebello-reticular fibres
AFFERENT EFFERENT
INFERIOR CEREBELLAR PEDUNCLE

39. Cerebral cortex
Pons Cerebellum
Spinal
Cord
Inferior
Olive
Vestibular
inputs
adapted from Purves
Principal inputs to
the cerebellum

40. The cerebellum receives direct afferents from the
spinal cord and from various centres in the
brainstem. The main afferents are
(1) Spinocerebellar. These terminate
predominantly in the paleocerebellum.
(2) Pontocerebellar. These are part of the cortico-
ponto-cerebellar pathway. They end
predominantly in the neocerebellum.
(3) Olivocerebellar. These end mainly in the
neocerebellum and partly in the paleocerebellum.
.

41. (5) Reticulocerebellar fibres from the reticular
formation of the pons and of the medulla.
The cerebellum also receives fibres from the
tectum, the arcuate nuclei, the accessory cuneate
nucleus, and from the sensory nuclei of the
trigeminal nerve.
(4) Vestibulocerebellar, from the vestibular nuclei,
and also direct fibres of the vestibular nerve

42. Cerebellar cortex
Deep nuclei
Red
Nucleus
Inferior
Olive
Vestibular
Nuclei
Thalamus
Cerebral
Cortex
adapted from Purves
Principal outputs of
the cerebellum

43. The main efferents of the cerebellum are :
(1) Cerebellorubral, to the red nucleus of the
opposite side.
(2) Cerebellothalamic, to the thalamus of the
opposite side.
(3) Cerebellovestibular, to the
vestibular nuclei.
(4) Cerebelloreticular, to the reticular
formation.
Some fibres from the cerebellum also
reach the inferior olivary nucleus, the
nucleus of the oculomotor nerve, and the
tectum.

44. Main connections of the cerebellum.

45. Connections between Cerebellum
and Spinal Cord
Spinocerebellar pathways convey to the
cerebellum proprioceptive information necessary
for controlling muscle tone and for maintaining
body posture. These pathways also carry
exteroceptive impulses.
(a) Direct pathways from spinal cord to
cerebellum
ventral spinocerebellar tract, and the dorsal
spinocerebellar.
Rostral spinocerebellar tract and the
cuneocerebellar tract .

46. (b) Indirect pathways from spinal cord to
cerebellum
• Spino-olivo-cerebellar;
• Spino-reticulo-cerebellar;
• Spino-vestibulo-cerebellar; and
• Spino-tecto-cerebellar pathways.
(c) Cerebello-spinal pathways
The cerebellum can influence the spinal cord
through the following pathways:
• Cerebello-rubro-spinal;
• Cerebello-vestibulo-spinal;
• Cerebello-reticulo-spinal;
• Cerebello-tecto-spinal; and
• Cerebello-thalamo-cortico-spinal.

47. Connections between Cerebellum and
Cerebral Cortex
(b) Cortico-olivo-cerebellar;
(c) Cortico-reticulo-cerebellar;
(d) Cortico-rubro-cerebellar;
(e) Cortico-tecto-cerebellar; and
(f) Cortico-spino-cerebellar.
(a)cortico-ponto-cerebellar

48. ARTERIAL SUPPLY OF CEREBELLUM
SUPERIOR CEREBELLAR ARTERY –
Branch of BASILAR ARTERY
Supply the superior surface of the cerebellum.
ANTERIOR INFERIOR CEREBELLAR ARTERY
Branch of BASILAR ARTERY
Supply the anterior part of inferior surface of
the cerebellum.
POSTERIOR INFERIOR CEREBELLAR ARTERY
Branch of VERTEBRAL ARTERY
Supply the posterior part of inferior surface of
the cerebellum.

50. EMBRYONIC
DEVELOPMENT

54. development of the cerebellum

57. Midline Cerebellar Function and
Function Test
Observation
• Posture, head position
• Gait
• Eye movements

58. • Tests of tendem-gait:-

59. Ataxia
• May affect limbs,
trunk, gait
(depends on part
of cerebellum
involved)
• Gait ataxia cause
due to lesion in
anterior lobe.
• Defective timing of
sequential
contraction of
agonist /antagonist
muscles

60. Ataxia
• Results in a
disturbance in
smooth
performance of
voluntary acts
• Without cerebellar
modulation, skilled
movements originating
in cerebral cortex are
inaccurate, poorly
controlled

61. Hypotonia:
• usually
accompanies acute
hemispheric
lesions
• Interestingly less
often seen in
chronic lesions
• Ipsilateral to the
side of a cerebellar
lesion
• More noticeable in
upper limbs and
proximal muscles

62. • Dysmetria= abnormal
excursions in movement

63. • Asynergia=
lack of synergy
of various
muscles while
performing
complex
movements (
movements
are broken up
into isolated,
successive
parts--
decomposition
of movement)

64. • Dysdiadochokinesia=Adiadochokinesia;
impaired performance of rapidly
alternating movement

65. Cerebellar Dysarthria
• Hemisphere lesions are associated with speech
disorders more often than vermal lesions
• Abnormalities in articulation and prosody (together
or independent)
• “scanning”, “slurring”, “staccato”, “explosive”,
“hesitant”, “garbled”
• Scanning speech is jerky and explosive.

66. •Hop on each foot

67. •Rhomberg Test

68. Cerebellar Hemispheric Function and
Function Test
• Finger-to-nose test

69. Cerebellar Hemispheric Function
Rapidly alternating movements

70. Cerebellar Hemispheric Function
• Heel-to-shin test

71. Features of Cerebellar Dysfunction
• Hypotonia
• Ataxia
• Dysarthria
• Tremor
• Ocular Motor Dysfunction
• Adiadochokinesia
• Scanning and jerky speech

72. • postural instability
• delayed initiation and termination of motor
actions
• inability to perform continuous, repetitive
movements
• errors in smoothness and direction of a
movement
• lack of coordingation or synergy of movement,
especially complex movements
• lack of motor plasticity or learning

73. Tremors
• rhythmic, alternating, or oscillatory movements
• can be a normal exaggeration of movement, a primary
disorder, or a symptom of a cerebellar disorder or
Parkinson's disease
• Diagnosis is usually clinical
• Treatment varies by etiology

74. General features
• Resting tremor : maximal at rest, decreases with
activity; usually a symptom of Parkinson's disease
• Postural tremor : maximal with limb in a fixed position
against gravity; gradual onset suggests physiologic or
essential tremor; acute onset suggests toxic /
metabolic disorder
• Intention tremor : maximal during movement toward a
target (finger-to-nose testing) ; suggests a cerebellar
disorder but may result from other diseases (MS,
Wilsons)

75. • Physiologic tremor: present normally -- usually so
slight that it is noticeable only under certain
conditions ; predominantly postural, fine and rapid
movements.
• most visible when hands are outstretched
• Amplitude may be increased (enhanced) by
• Anxiety
• Stress
• Fatigue
• Metabolic disorders (eg, hyperadrenergic states
such as alcohol or drug withdrawal or
thyrotoxicosis)

76. Certain drugs (eg, caffeine, other
phosphodiesterase inhibitors, β-adrenergic
agonists, corticosteroids)
Alcohol and other sedatives usually
suppress it.

77. Oculomotor dysfunction
•Nystagmus frequently seen in cerebellar
disorders
• To and fro oscillatory movements of eye ball,
• Gaze-evoked nystagmus, upbeat nystagmus,
rebound nystagmus, opticokinetic nystagmus may
all be seen in midline cerebellar lesions

78. •Cerebellar CONGENITAL affective disorder
• Impaired executive function,
• personality, emotional and behavioral changes
• Grammatical errors inspeech
• Patchy memory loss
• Show inattention
• Ataxic or unsteady gait

79. RADIOLOGY

80. Used to detect Infraction,Tumours,Calcification,
and Haemorrhage.
In this procedure, X-RAY beam traces an arc at
Multiple angle around a section of the head.
Resulting transverse section reproducedby the
computer on its mnitor screen.
Generates 3D view,
Hypodense(dark) and hyperdense(bright) appears
CT SCAN:
X-RAY COMPUTEDTOMOGRAPHY

81. CT SCAN OF CEREBELLUM

82. •Provide superior imaging than CT-SCAN
•Used to confirm diagnosis of Neoplasm,
Vascular disease, posterior cranial fossa lession,
Cervicomedullary lesion or intracranial pressure
Disorder.
•Body is exposed to high magnetic field which permis
Protons in the tissue to arrange themselves in the
Related field
• then a pulse of radiowaves `reads` these ion pattern
And a coloured image is form on the monitor
• no risk of ionizing radition
MRI:
MAGNETIC RESONANCE IMAGING

83. MRI OF CEREBELLUM

84. MRI THROUGH SAGITAL SECTION

85. fMRI (functional magnetic resonance imaging) of a volunteer
executing repetitive finger movements of the right hand.