The presentation describes the anatomy of the cerebellum and its connections and touches upon the clinical features very briefly

1. Cerebellum and Its
Connections
-By Mittal Saumya Harsh
--September 2, 2014

2. FUNCTIONS OF
CEREBELLUM

3. Functions of Cerebellum
 Principally a motor organ responsible
for
◦ Coordination of movements esp skilled
movements
◦ Control of posture, gait and tone
◦ Initiation and modulation of willed
movements generated in cerebrum
 Motor activities don’t reach conscious
kinesthetic perception.
 May modulate emotional state and
cognition

4. In the words of Gordon Holmes, lesions
of cerebellum, do not cause weakness,
but rather loss of coordination and
inability to gauge and regulate the “rate,
range and force” of movement.

5. GROSS ANATOMY
2 large Cerebellar hemispheres
Small Unpaired Median Vermis
Small Midline Flocculonodular Lobe

6.  Three Parts-
◦ Cerebellar
hemispheres
 Appendicular
coordination
◦ Vermis
 Connection between
hemispheres
 Gait and axial function
◦ Flocculonodular lobe
 Paired lateral flocculi
with midline nodulus
 Eye movements &
balance
 Cerebellar tonsils- small, rounded lobules on
inferior aspects of cerebellar hemispheres, just
above the foramen magnum

7. PHYLOGENETIC
DIVISIONS OF
CEREBELLUM
ArchiCerebellum (Oldest)
PaleoCerebellum (Relatively small in humans)
Corpus
NeoCerebellum (Largest subdivision in humans)
Cerebelli

8. Phylogenetic Divisions
 Flocculonodular
Lobe
◦ ArchiCerebellum
 Anterior Lobe
◦ PaleoCerebellum
 Posterior Lobe
◦ NeoCerebellum
◦ Middle divisions of
vermis and their
lateral extensions.

9. ANATOMICAL
SUBDIVISIONS OF
CEREBELLUM
VestibuloCerebellum Ventral Spinocerebellar tract
SpinoCerebellum
PontoCerebellum Dorsal Spinocerebellar tract

10. Vestibulocerebellum
 Same as the
flocculonodular
lobe
 Proprioceptive
fibers from the
Vestibular nuclei
 Functions
◦ Eye movement
◦ Gross balance
and orientation in
space

11. Spino/Paleocerebellum (evolved
when extremity control was not a concern)
 Anterior and part of
Posterior Vermis (and
paravermal cortex)
 Proprioceptive fibers from
muscles and tendons of
limbs
 Functions
◦ Influence posture,
◦ muscle tone,
◦ axial muscle control,
◦ locomotion
 Dorsal Spinocerebellar
Tract from lower limbs
 Ventral Spinocerebellar
tract from upper limbs

12. Pontocerebellum
 Roughly the same
as neocerebellum
 Afferent from
pontine nucleus
and brachium
pontis
 Coordination of
skilled movements
initiated at cerebral
cortical levels

13.  These divisions are incomplete. It is
now appreciated that certain portions
of cerebellar hemispheres are also
involved in other functions e.g.
◦ Tactual
◦ Visual
◦ Auditory
◦ Visceral

14. LONGITUDINAL
ORGANIZATION OF
CEREBELLUM
Vermian zone,
Paravermian zone,
Lateral zone

15. Functions of Longitudinal
Divisions
◦ Vermian (median)
 Coordinates movements of eyes and body with respect to
gravity
 Coordinates movement of head in space
◦ Paravermian (intermediate)
 Influences postural tone
 Influences individual movements of individual limbs
◦ Lateral
 Coordination of movements of ipsilateral limbs
 Other functions

17. Flocculonodular Lobe
 Connections are to
 Afferent
◦ Labyrinths
◦ Vestibular centers
◦ Spinal cord
◦ Brainstem
◦ Reticular formation
◦ Olivary bodies
 Efferent
◦ Vestibular nuclei
◦ Vestibulospinal tract
◦ Reticular formation
 The manifestations
are difficult to
separate from
invariably involved
vestibular findings.
 Isolated FN lobe
dysfunction is usually
seen in children in-
 Ependymomas
 Medulloblastomas

18. Paleocerebellum
 Afferent connections
◦ Anterior spinocerebellar tract
◦ Trigeminocerebellar fibers
◦ Input from vestibular nucleus
◦ Corticocerebellar fibers
 Efferent connections
◦ Vestibular nucleus
◦ Brainstem
◦ Spinal cord

19. Neocerebellum
 Afferent connections
◦ Corticopontine/corticopontocerebellar
fibers
◦ Spinocerebellar fibers (few)
 Efferent connections
◦ To red nucleus through
◦ To thalamus Dentate
◦ To cerebral cortex Nucleus

21. DEEP NUCLEI OF
CEREBELLUM
Dentate nucleus
Emboliform nucleus
Globus nucleus
Fastigial nucleus

22. Structure of cerebellum
 Cerebellum is a composite of
◦ White matter core
◦ Grey matter thin cortex
◦ Cerebellar nuclei- deep grey matter
structures
 Nuclei
◦ Dentate nucleus
◦ Emboliform nucleus nucleus
◦ Globose nucleus interpositus
◦ Fastigial nucleus

23.  Vermis Fastigial nucleus
 Intermediate Globose nucleus
Emboliform nucleus
 Lateral Dentate nucleus
Spinocerebellar (Intermediate) have few connections with fastigial nucleus as well

24. Fibers from Nuclei

25.  Therefore, motor control of the
cerebellum is by connection with
◦ Motor cortex
◦ Brainstem nuclei
◦ Descending motor pathways

26. Functions of Deep Nuclei
Dentate Nucleus Fastigial Nucleus
 Receives fibers from-
◦ Premotor cortex.
◦ Supplementary motor
cortex.
 Initiate volitional
movements.
 Inactivation of dentate
nucleus delayed initiation
of such movement.
 Controls antigravity
muscles and other
muscle synergies in
standing and walking.

27. Nuclei Interpositus Prepositus Nucleus
 Cerebrocortical
projections via
pontocerebellar system.
 Spinocerebellar
projections
◦ Information from Golgi
tendon organs, muscle
spindles, cutaneous
afferents, subcutaneous
interneurons.
◦ Fires when movement has
started.
◦ Dampens physiological
tremors- Intention tremors if
interrupted
 Known to be neural
integrator of horizontal
eye movements.
 May also function in
postural balance in view
of its connections with
vestibular nuclei and
vestibulocerebellum.
 Responsible for volitional
oscillations.

28. CEREBELLAR
PEDUNCLES
Superior Cerebellar Peduncle
Middle Cerebellar Peduncle
Inferior Cerebellar Peduncle

29. Inferior Cerebellar Peduncle

30.  Posterior spinocerebellar tract, originates from
posterior nucleus. Carries proprioceptive and
exteroceptive information from trunk and I/L lower
limbs.
 The cuneocerebellar tract, originating in the external
arcuate nucleus transmits proprioceptive information
from the upper extremity and neck.
 The olivocerebellar tract carries somatosensory
information from the contralateral inferior olivary
nuclei.
 The vestibulocerebellar tract transmits information
from vestibular receptors on both sides of the body.
 The reticulocerebellar tract arises in the lateral
reticular and paramedian nuclei of the medulla.
 The arcuatocerebellar tract arises from the arcuate
nuclei of the medulla oblongata.
 The trigeminocerebellar tract arises from the spinal
and main sensory nuclei of the trigeminal nerve.

31. Middle Cerebellar Peduncle
 Brachium Pontis
 Greatest peduncle
 Traversed by
pontocerebellar
tracts
 Connects cerebral
cortices to C/L
cerebellar
hemisphere

32.  Pontocerebellar
(corticopontocerebellar) tract arises in
the contralateral pontine gray matter
and transmits impulses from the
cerebral cortex to the intermediate and
lateral zones of the cerebellum.

33. Superior Cerebellar Peduncle
 Brachium
Conjunctivum
 Principally efferent
 Chief efferent fibres
◦ Dentatorubral
◦ Dentatothalamic
 Also
◦ Anterior
spinocerebellar
◦ Cerebellovestibular
tract

34.  Afferent fibres include
◦ The ventral spinocerebellar tract transmits
proprioceptive and exteroceptive information
from levels below the midthoracic cord.
◦ The tectocerebellar tract, arising in the
superior and inferior colliculi carries auditory
and visual information.
◦ The trigeminocerebellar tract carries
proprioceptive fibers from the
mesencephalon and tactile information from
the chief sensory nucleus of the trigeminal
nerve.
◦ The cerulocerebellar tract carries fibers from
the nucleus ceruleus.

35.  Efferent fibers include
◦ The dentatorubral tract carries output to
the contralateral red nucleus. Many of the
fibers ending in this nucleus are branches
of the larger dentatothalamic tract.
◦ The dentatothalamic tract transmits output
to the contralateral ventrolateral nucleus
of the thalamus.

36. NEURONAL
ORGANIZATION
3 layered structure that has 5 types of neurons
Molecular layer- Stellate cells, Basket cells- inhibitory
Layer of Purkinje cells (inhibitory)- GABA
Granular layer- Granule cells (excitatory), Golgi
interneurons

37. 3 types of fibres of cortex
 Parallel fibres-
◦ From granule cells
◦ Along long axis
◦ Excite the Purkinje cells
in a Million: One ratio
◦ Excite the Stellate and
Basket cells that inhibit
Purkinje cells
 Mossy fibres-
◦ From spinocerebellar,
pontine, vestibular and
reticular nuclei.
◦ End in granule layer
◦ Excitatory

38.  Climbing fibers
◦ Originate in inferior
olivary nucleus.
◦ Vine like
configuration around
Purkinje.
◦ Excitatory effect on
Purkinje cells.

39. CLINICAL FEATURES

40. Normal Movement
 Performance of a normal movement
needs-
◦ To begin movement-
 Contraction of agonists, with
relaxation/modified tone of antagonist.
 Synergist reinforce the movement.
 Fixating muscles prevent displacement and
maintain tone and posture
◦ To end movement-
 Contraction of antagonist, with agonist
relaxation .

41. Lesions in Cerebellum cause
 Incoordination
◦ Speed of initiation of movement is slowed.
◦ Irregularity and slowing of movement itself.
◦ Excursion of limb arrested prematurely (short
agonist burst).
◦ The limb overshoots the mark- hypermetria (long
agonist burst).
 Tremor
◦ The intention or action tremor of finger
 Is chiefly instability of shoulder
 Tremor is perpendicular to trajectory.

42.  All defects of volitional control are evident on
rapid alternating movements-adiadochokinesis.
 Coarse tremors
◦ Wing beating tremor
◦ Titubation (AP plane)
 Altered Ocular movement
◦ Nystagmus
◦ Skew deviation
◦ Ocular flutter
◦ Ocular myoclonus
 Disorder of speech
◦ Slurring dysarthria
◦ Scanning dysarthria

43.  Disorder of equilibrium and gait
◦ Lesion of anterior vermis
 Diminished muscle tone

44. SOMATOTOPICAL
CEREBELLUM
Cerebellar cortex (esp. anterior lobe) is somatotopical.

45.  Sensory map is similar to the motor map.

46. MOLLARET TRIANGLE
Cerebellar-Reticular- Cerebellar Feedback System

47. Superior Cerebellar Peduncle
Decussate
Central Tegmental Fasciculus
Venteromedial Tegmentum of Brainstem
1. Inferior Olivary Nuclei of Medulla
2. Reticulotegmental nuclei of pons
3. Paramedian reticular nuclei of pons
Inferior Cerebellar Peduncle
Anterior Lobe of Cerebellum

48. CLINICAL FINDING SENSORY ATAXIA CEREBELLAR ATAXIA
Loss of vibration and position sense +
Areflexia +
Nystagmus +
Hypotonia + +
Ataxia much worse with eyes closed +
Past pointing +

49. Thank You