170 Cerebellum.pdf………………....…….……………………..

Detailed description of position nd function

1. The tailor who couldn’t
thread his needle

2. Mr. C, a 50 year old male, a tailor by profession,
presented with history of frequent falls. On enquiry,
he admitted that he found it difficult to thread the
needle, and experienced shakiness of hands when
he attempted to stitch.
His speech was not smooth, words seemed to come
in bursts, with stress on some syllables
His right shoulder was stooped lower compared to
left. He was seen to walk with his feet wide apart,
and swaying to a side.
When asked to touch the tip of his nose with the
index finger of outstretched hand, with his eyes
closed, his right finger seemed to move past his nose

3. •Which part of the nervous system is affected?
•What is the site and side of lesion?
•What are the other functions that may be affected?
•What is the basis of these symptoms and signs?

4. “Silent area” of the brain
Cerebellum

5. Learning objectives:
At the end of the session, learners should be able to:
1.Describe the functional anatomy of cerebellum
2.List the physiological divisions of cerebellum and their
functional correlates
3.Describe the afferent and efferent connections of
cerebellum
4.Explain the internal neural circuitry of the cerebellum
5.Describe the functions of cerebellum in motor activity
6.List the features/manifestations of cerebellar lesion
7.Explain the basis of the above features

6. Cerebellum
How is it that the cerebellum can be so important when it has no direct
ability to cause muscle contraction?
➢It helps sequence the motor activities to perform a complex skilled
movement
➢monitors and makes corrective adjustments in the body’s motor
activities while they are being executed so that they will conform to
the motor signals directed by the cerebral motor cortex and other
parts of the brain.
➢Provides for postural adjustments required for equilibrium especially
while performing rapid movements
The ‘Little brain’

7. Cerebellum
Anatomy
Posterior view of the cerebellum
Describe the functional
anatomy of cerebellum

8. Cerebellum
Anatomy
Anatomical lobes of the cerebellum as seen from the lateral side
Primary fissure
Posterolateral fissure
Describe the functional
anatomy of cerebellum

9. Cerebellum
Anatomy
Functional parts of the cerebellum as seen from the postero-inferior view, with the
inferior-most portion of the cerebellum rolled outward to flatten the surface
Describe the functional
anatomy of cerebellum

10. Vestibulo-
Cerebellum
Provides neural circuits
for most of the body’s
equilibrium movements
Spino-cerebellum
Provides neural circuits for coordinating movements of
distal part of the limbs
Cerebro-
cerebellum
Provides neural circuits
to plan sequential
voluntary movements
Physiological/ Functional
divisions of cerebellum
List the physiological divisions of cerebellum and their functional correlates

11. Evolutionary divisions of cerebellum
Archicerebellum
(oldest)
Paleocerebellum
(old)
Neocerebellum
(new)

12. Cerebellum
Topographical Representation
Somatosensory projection areas in the cerebellar cortex
Body
parts
Motor
cortex
Brainstem
Red
nucleus
Reticular
formation
Motor
cortex

13. Cerebellum
Topographical Representation
Somatosensory projection areas in the cerebellar cortex
Somatosensory
area
Motor cortex
(Premotor
cortex)
Sensory
association
areas

14. Cerebellum
Internal structure
Coronal section of the cerebellum; posterior view
Describe the functional
anatomy of cerebellum

15. Deep cerebellar nuclei
Cerebellum
Internal structure
Emboliform
Interposed nucleus =
Globose + Emboliform
Describe the functional
anatomy of cerebellum

16. Deep cerebellar nuclei in relation to functional areas
Cerebellum
Internal structure
Describe the functional
anatomy of cerebellum

17. CONNECTIONS OF
CEREBELLUM

18. Inputs & Outputs of cerebellum
Describe the afferent and efferent connections of cerebellum

19. Connections of Cerebellum
Afferent tracts Efferent tracts
Superior cerebellar
peduncle
Ventral spinocerebellar
Tectocerebellar
Rubrocerebellar
Cerebello-rubral
Cerebello-thalamic
To midbrain reticulum
To Oculomotor nucleus
& Tectum
Middle cerebellar
peduncle
Cerebro-
Ponto-Cerebellar
fibers
Inferior cerbellar
peduncle
Dorsal spinocerebellar
Cuneocerebellar
Reticulocerebellar
Vestibulocerebellar
Olivocerebellar
Cerebelloreticular
Cerebellovestibular
Cerebello-Olivary
Describe the afferent and efferent connections of cerebellum

20. CORTEX
MIDBRAIN
PONS
MEDULLA
SPINAL CORD
Describe the afferent and efferent connections of cerebellum

21. Afferents to cerebellum
CORTEX
MIDBRAIN
PONS
MEDULLA
SPINAL CORD
VESTIBULOCEREBELLLAR TRACTS
Vestibular nuclei
Vestibular
apparatus
Describe the afferent and efferent connections of cerebellum

22. Afferents to cerebellum
CORTEX
MIDBRAIN
PONS
MEDULLA
SPINAL CORD
Superior
Cerebellar
peduncle
Inferior
Cerebellar
peduncle
SPINOCEREBELLAR TRACTS
DORSAL
VENTRAL
Describe the afferent and efferent connections of cerebellum

23. Afferents to cerebellum
CORTEX
MIDBRAIN
PONS
MEDULLA
SPINAL CORD
RETICULO CEREBELLAR TRACT
Inferior
Cerebellar
peduncle
Reticular formation
Describe the afferent and efferent connections of cerebellum

24. Afferents to cerebellum
CORTEX
MIDBRAIN
PONS
MEDULLA
SPINAL CORDInferior
Cerebellar
peduncle
Inferior Olivary nucleus
OLIVO-CEREBELLAR TRACT
Describe the afferent and efferent connections of cerebellum

25. Afferents to cerebellum
CORTEX
MIDBRAIN
PONS
Pontine nuclei
Middle
Cerebellar
peduncle
CORTICO-PONTO-CEREBELLAR
TRACT
Describe the afferent and efferent connections of cerebellum

26. Afferents to cerebellum
CORTEX
MIDBRAIN
Superior
Cerebellar
peduncle
Red nucleus
RUBRO-CEREBELLAR
TRACT
Describe the afferent and efferent connections of cerebellum

27. Afferents to cerebellum
CORTEX
MIDBRAIN
Superior & Inferior
colliculi
TECTO CEREBELLAR
TRACT
Superior
Cerebellar
peduncle
Describe the afferent and efferent connections of cerebellum

28. Efferents from cerebellum
CORTEX
MIDBRAIN
PONS
MEDULLA
SPINAL CORD
Red nucleus
Thalamus
Dentate
nucleus
Rubrospinal
tract
Cerebello-Thalamic
&
Cerebello-Rubral
connections
Describe the afferent and efferent connections of cerebellum

29. Connection of cerebellum with cerebrum
Corticospinal
&
Rubrospinal tracts
Describe the afferent and efferent connections of cerebellum

30. Efferents from cerebellum
CORTEX
MIDBRAIN
MEDULLA
SPINAL CORD
CEREBELLO-VESTIBULAR TRACTS
Vestibular nuclei
Fastigius
Vestibulospinal tract
Describe the afferent and efferent connections of cerebellum

31. Efferents from cerebellum
CORTEX
PONS
MEDULLA
SPINAL CORD
CEREBELLO RETICULAR TRACT
Reticular formation
Reticulospinal tract
Describe the afferent and efferent connections of cerebellum

32. CORTEX
MIDBRAIN
PONS
MEDULLA
Inferior Olivary nucleus
CEREBELLO-OLIVARY TRACT
Olivo-spinal tract
Efferents from cerebellum
Describe the afferent and efferent connections of cerebellum

33. Cerebellum
Functional unit of cortex
Explain the internal
neural circuitry of
the cerebellum

34. Internal arrangement in a cerebellar folium
Cell types:
•Basket cell
•Stellate cell
•Purkinje cell
•Granule cell
•Golgi cell
•Cells of deep nuclei
Fiber types:
•Climbing fiber
•Mossy fiber
Molecular layer
Purkinje cell layer
Granular layer
From Inferior olivary nucleus
From all other input areas
Embedded in
Medullary zone
Explain the internal neural circuitry of the cerebellum

35. Cerebellum
Internal circuit
Input signal
to cerebellum
One of the deep
cerebellar nuclei
Output signal
Explain the internal
neural circuitry of
the cerebellum

36. Cerebellum
Internal circuit
Input signal
to cerebellum
One of the deep
cerebellar nuclei
Corresponding
area of the
cerebellar cortex
overlying the
deep nucleus
Output signal
Explain the internal
neural circuitry of
the cerebellum

37. Cerebellum
Internal circuit
•Deep nuclear cell ----
•Granule cell ----
•Golgi cell ----
•Purkinje cell ----
•Stellate and
•Basket cells ----
Explain the internal
neural circuitry of
the cerebellum
Medullary core
Granular layer
Purkinje cell layer
Molecular layer
Activity of different cell types of cerebellum
Excitatory output
Excitatory to
•Purkinje cell
•Golgi cell
•Basket cell
•Stellate cell
Inhibitory to Deep nuclear cell
Inhibitory to Granule cell
Inhibitory to Purkinje cell

38. Cerebellum
Neuronal circuit of the functional unit of cortex
Explain the internal
neural circuitry of
the cerebellum

39. Cerebellum
Neuronal circuit of the functional unit of cortex
Explain the internal
neural circuitry of
the cerebellum

40. Cerebellum
Neuronal circuit of the functional unit of cortex
Purkinje cell
Explain the internal
neural circuitry of
the cerebellum

41. Cerebellum
Neuronal circuit of the functional unit of cortex
Granule cell
Explain the internal
neural circuitry of
the cerebellum

42. Cerebellum
Neuronal circuit of the functional unit of cortex
Parallel fibres
Explain the internal
neural circuitry of
the cerebellum

43. Cerebellum
Neuronal circuit of the functional unit of cortex
Golgi cell
Explain the internal
neural circuitry of
the cerebellum

44. Cerebellum
Neuronal circuit of the functional unit of cortex
Basket cell
Stellate cell
Explain the internal
neural circuitry of
the cerebellum

45. Cerebellum
Neuronal circuit of the functional unit of cortex
Climbing fibre
From Inf Olivary nucleus
Explain the internal
neural circuitry of
the cerebellum

46. Cerebellum
Neuronal circuit of the functional unit of cortex
Mossy fibre
From all other afferents Explain the internal
neural circuitry of
the cerebellum

47. Cerebellum
Function in overall motor control
Describe the functions of cerebellum in motor activity

48. Cerebellum
Vestibulocerebellum
•Body equilibrium and postural
control
•Muscle tone
•Vestibulocerebellum is important in
postural adjustments in muscle
contractions of the spine, hips, and
shoulders during rapid changes in
body positions using inputs from
the vestibular apparatus.
•Vestibulo-ocular reflex
•Head, Neck and Eye movements in
response to acceleration

Describe the functions of cerebellum in motor activity

49. Cerebellum
Function in overall motor control
Describe the functions of cerebellum in motor activity

50. Cerebellum
Spinocerebellum
1. Feedback Control of Distal Limb Movements by Way of the Intermediate
Cerebellar Cortex and the Interposed Nucleus
Intended
sequential
plan of movement
for the next few
fractions of a
second
COMPARATOR FUNCTION
Describe the functions
of cerebellum in motor
activity

51. Cerebellum
Spinocerebellum
Describe the functions of cerebellum in motor activity

52. Cerebellum
Spinocerebellum
Muscle spindles
Golgi tendon organs
Large cutaneous tactile receptors
Joint receptors
Vermis &
Intermediate zones
of the same side
Inferior cerebellar peduncle
DORSAL SPINOCEREBELLAR TRACT
Spinal cord
Describe the functions of cerebellum in motor activity

53. Cerebellum
Spinocerebellum
Superior cerebellar peduncle
Spinal cord
VENTRAL SPINOCEREBELLAR TRACT
Both sides of
cerebellum
Motor signals from
corticospinal and rubrospinal
tracts
Efference
copy
Describe the functions of cerebellum in motor activity

54. Cerebellum
Spinocerebellum
Intended
sequential
plan of movement
for the next few
fractions of a
second
•Corticopontocerebellar
tract
•Ventral
spinocerebellar tract
•Olivary–Purkinje cell
system
Smooth, coordinated
movements of the
agonist and
antagonist muscles
of the distal limbs for
performing acute
purposeful patterned
movements.
Describe the functions of cerebellum in motor activity

55. Cerebellum
Spinocerebellum
2. Prevent Overshoot and to “Damp” Movements
•Almost all movements of the body are “pendular.”
•Because of momentum, all pendular movements have a tendency to overshoot.
•If overshooting occurs in a person whose cerebellum has been destroyed, the
conscious centers of the cerebrum eventually recognize this occurrence and
initiate a movement in the reverse direction to attempt to bring the arm to its
intended position.
•However, the arm, by virtue of its momentum, overshoots once more in the
opposite direction, and appropriate corrective signals must again be instituted.
•Thus, the arm oscillates back and forth past its intended point for several cycles
before it finally fixes on its mark. This effect is called an action tremor or
intention tremor.
•If the cerebellum is intact, appropriate learned, subconscious signals stop the
movement precisely at the intended point, thereby preventing the overshoot and
the tremor.
Describe the functions
of cerebellum in motor
activity

56. Cerebellum
Spinocerebellum
Cerebral
cortex
Powerful
contraction
Corticospinal
motor system in
the cerebral cortex
Deep cerebellar
nuclei
Pons
Initiation of
contraction
Agonist
muscle
Spinal cord
Brain stem
Mossy fibres
Turn off signal to
agonist
Deep cerebellar nuclei
Mossy fibres
Parallel fibres
Granule cells
Cerebellar cortex
Purkinje cells
Describe the functions of cerebellum in motor activity

57. Cerebellum
Spinocerebellum
3. Control of Ballistic movements
•Most rapid movements of the body, such as the movements of the fingers
in typing, occur so rapidly that it is not possible to receive feedback
information either from the periphery to the cerebellum or from the
cerebellum back to the motor cortex before the movements are over.
•These movements are called ballistic movements, meaning that the entire
movement is preplanned and set into motion to go a specific distance and
then to stop.
•Another important example is the saccadic movements of the eyes, in
which the eyes jump from one position to the next when reading or when
looking at successive points along a road as a person is moving in a car.
Describe the functions of cerebellum in motor activity

58. Cerebellum
Cerebrocerebellum
1.Planning of sequential movements
2.Timing of the sequential movements
Describe the functions of cerebellum in motor activity

59. Cerebellum
Cerebrocerebellum
1.Planning of sequential movements
Plan
Primary
somatosensory
area
Pre-motor
cortex
Association
somatosensory
area
Lateral
hemispheres of
cerebellum
Basal
ganglia
Dentate
nuclei
Corticopontocerebellar tract
Describe the functions
of cerebellum in motor
activity

60. Cerebellum
Cerebrocerebellum
1.Planning of sequential movements
Plan
Primary
somatosensory
area
Pre-motor
cortex
Association
somatosensory
area
Lateral
hemispheres
of cerebellum
Basal
ganglia
Dentate
nuclei
Cerebellothalamocortical tract
Describe the functions
of cerebellum in motor
activity

61. Cerebellum
Cerebrocerebellum
1.Planning of sequential movements
Plan
Primary
somatosensory
area
Pre-motor
cortex
Association
somatosensory
area
Lateral
hemispheres
of cerebellum
Basal
ganglia
Dentate
nuclei
Lateral cerebellar zones
appear to be involved not
with what movement is
happening at a given
moment but with what will
be happening during the
next sequential movement
a fraction of a second or
perhaps even seconds
later.
Describe the functions
of cerebellum in motor
activity

62. Cerebellum
Cerebrocerebellum
2.Timing of the sequential movements
➢In the absence of these cerebellar zones, one loses the subconscious ability to
predict how far the different parts of the body will move in a given time.
➢Without this timing capability, the person becomes unable to determine when
the next sequential movement needs to begin.
➢As a result, the succeeding movement may begin too early or, more likely, too
late.
➢Therefore, lesions in the lateral zones of the cerebellum cause complex
movements (writing, running, or even talking) to become incoordinate and
lacking ability to progress in orderly sequence from one movement to the next.
➢Such cerebellar lesions are said to cause failure of smooth progression of
movements.
Describe the functions of cerebellum in motor activity

63. Cerebellum
Cerebrocerebellum
3. Servomechanism
➢Cerebellum plays important role in learning of motor skills
➢Once learnt, sequential movements can be executed
without interruption
➢Cerebral cortex discharges signals to execute already
programmed and stored
➢If any disturbance occurs, cerebrocerebellum immediately
influences the cortex and corrects the movements
Describe the functions of cerebellum in motor activity

64. Cerebellum
Cerebrocerebellum
4. Extra-motor Predictive Functions
➢Rates of progression of both auditory and visual phenomena can be predicted
by the brain, but both of these require cerebellar participation.
➢As an example, a person can predict from the changing visual scene how
rapidly he or she is approaching an object.
➢It is quite possible that the cerebellum provides a “time base,” perhaps using
time-delay circuits, against which signals from other parts of the central
nervous system can be compared;
Interprets rapidly changing spatiotemporal relations in sensory information
Describe the functions of cerebellum in motor activity

65. Recap of Cerebellar functions:
•Control of posture and equilibrium
•Effect on muscle tone
•Control of voluntary motor activity
•Regulation of time, rate, range, force and direction of
muscular activity
•Control of agonistic and antagonistic muscles
•Appropriately timed turn on and turn off signals
•The Damping of oscillation
•Control of ballistic movements
•Planning the sequence and timing of
components of complex movements
•Servomechanism
•Extra motor predictive functions
Describe the functions of cerebellum in motor activity

66. CEREBELLAR LESIONS

67. Common causes of cerebellar lesion
•Vascular
•Trauma
•Infections
•Tumors
•Degenerative diseases
List and explain the features of cerebellar lesion

68. General features of cerebellar lesions:
•No paralysis or sensory deficit
•Cortical lesions: transient abnormalities; compensated
•Deep nuclear lesions: marked and persistent
abnormalities
•Lesions of vermis: bilateral dysfunction
•Lesions of cerebellar hemisphere: deficits on the
ipsilateral side
Why?!
List and explain the features of cerebellar lesion

69. Effects of cerebellar lesions:
Function Dysfunction Manifestation
Tone Hypotonia 1.Disturbance
of posture
and attitude
2.Pendular
movements
Posture and
equilibrium
Dysequilibrium 1.Abnormal
posture
2.Abnormal
gait
List and explain the features of cerebellar lesion

70. Effects of cerebellar lesions:
Function Dysfunction Manifestation
Control of rate,
range and
direction of
movement
Control of
agonists and
antagonists
Dysmetria and
Ataxia
Incoordinated
movements
List and explain the features of cerebellar lesion

71. Effects of cerebellar lesions:
Function Dysfunction Manifestation
Timing of turn on and
turn off
1.Overshooting
2.Inability to apply
brake
1.Past pointing
2.Rebound
phenomenon
Damping of pendular
motion
oscillation 1.Intention tremors
2.Nystagmus
Complex motor
activity
Ballistic movements
1.Decomposition
2.Failure of
progression
1.Dys-
diadochokinesia
2.dysarthria
List and explain the features of cerebellar lesion

72. 1. Hypotonia
•Loss of tone of ipsilateral muscles
•Due to loss of cerebellar facilitation
•Attitude changes:
•Rotation of face to normal side ( pull of
normal muscles)
•Drooping of ipsilateral shoulder
•External rotation and abduction of affected
leg
•Trunk bent and concave towards affected
side (weight of body shifted to normal side)
•Effects on deep tendon reflexes:
•Weak and pendular
•Eg: pendular knee jerk due to hypotonia of
quadriceps
List and explain the features of cerebellar lesion

73. 2. Dysequilibrium
•Usually due to lesion of flocculonodular
lobe
•Inability to maintain upright posture
•Stands with feet wide apart
•Gait is
•Broad based
•Clumsy
•Sways from side to side
•Described as “drunken gait”
•Tested by ‘Tandem walking test’
List and explain the features of cerebellar lesion

74. 3. Dysmetria and Ataxia
•Dysmetria: inappropriate rate, range, force
and direction of movement
•Ataxia: lack of co-ordianation resulting in
clumsy movements
•Incoordianation of agonist and antagonist
muscles: Asynergia
List and explain the features of cerebellar lesion

75. •Past pointing:
•Inability of subconscious motor control system to
regulate the exact range of movement
•Movement often overshoots the intended mark
•Tested by ‘Finger – Nose test’
•Rebound phenomenon:
•Inability to ‘brake’ or ‘check’ a movement
•Due to loss of precisely timed ‘turn off’ signals
List and explain the features of cerebellar lesion

76. 4. Oscillation and Tremors:
•All movements are pendular and tend to oscillate
if not checked
•Unavailability of cerebellar damping leads to
oscillation
•Overshooting on one side corrected by conscious
areas of brain
•But overcorrection leads to overshoot on the
other side
•This results in oscillatory movements: Tremors
List and explain the features of cerebellar lesion

77. •Tremors of cerebellar lesions are Intention
tremors
•Evident on attempting purposeful activity
•Coarse, rhythmic
•Worsen as the target is approached
•Tested by Finger- Nose test
•Nystagmus:
•Rapid to and fro movements of eyeballs on attempting
gaze fixation
•Due to tremulous movements of eyes rather than
steady fixation
•Another manifestation of failure of damping by
cerebellum
List and explain the features of cerebellar lesion

78. 5. Decomposition of movements:
•Inability to perform complex movements involving
simultaneous motion at many joints
•Performed one movement at a time, at one joint
after the other
•Dysdiadochokinesia:
•Failure to perceive instantaneous positions of various
body parts and predict their positions in the near future
•Failure to regulate timing and extent of individual
movements
•Succeeding movements occur either too soon on too
late
List and explain the features of cerebellar lesion

79. •Dysarthria:
•Speech requires precise and coordinated
sequence of activity of vocal cords, muscles of
larynx, pharynx, tongue, mouth and respiratory
muscles
•Requires active cerebellar control
•Cerebellar lesion leads to incoordination
•Some syllables are unduly emphasized and
prolonged; others are too weak and short
•Speech often unintelligible
•Or described as “scanning” or “staccato”
List and explain the features of cerebellar lesion

80. •Inability to perform ballistic movements
•Eg: playing musical instruments, typewriting, etc.
6. loss of extra-motor predictive ability
•Inability to use changing auditory and visual cues
•Inability to judge target distance and speed of approach
List and explain the features of cerebellar lesion

81. Summary:
•Cerebellar lesions are marked and persistent if
deep nuclei are damaged
•Cerebellar lesions produce ipsilateral deficit
•Manifest as:
1.Hypotonia
2.Dysequilibrium
3.Dysmetria and Ataxia
4.Past-pointing and Rebound
5.Intention tremors and Nystagmus
6.Dysdiadochokinesia
7.Dysarthria

82. Clinical tests for cerebellum:
1.Gait/ Tandem walking test
2.Finger – Nose test
3.Knee – Heel test
4.Rebound phenomenon:
Walk – Stop – Turn
Forearm flexion against resistance
5.Dysdiadochokinesia

83. Cerebellar signs

84. Cerebellar gait/ Drunken gait

85. Tandem walking test