Lecture on PHYSIOLOGY of Cerebellum by Dr. Roomi

8/13/2019 Lecture on PHYSIOLOGY of Cerebellum by Dr. Roomi
1/42
PHYSIOLOGY
of
CEREBELLUM
By
Dr. Mudassar Ali Roomi (MBBS, M.Phil.)Assistant Professor Physiology

2/42
CEREBELLUM
Largest part of hindbrain.
LOCATION: Posterior
cranial fossa behind
pons & medulla.
ANATOMY: Covered
above by meninges
(Tentorium Cerebelli). Has 2 hemispheres
joined by Vermis.

3/42

4/42
LOBES:three1) anterior lobe
2) posterior / middle lobe
3) flocculo nodular lobe
FISSURES:two1) Primary fissure (v
shaped). Part ofcerebellum above thisfissure is anterior lobe.
2) Uvulo-nodular fissure(separates posterior lobefrom flocculo nodularlobe).

5/42
FUNCTIONAL ZONES OF CEREBELLUM
Each cerebellar
hemisphere has 2
functional zones,
intermediate zone&lateral zone.

6/42
Topographical representation
Axial parts of body
represented in Vermis.
Limbs & facial region
Intermediate zone.
http://www.google.com/url?sa=i&rct=j&q=WHITE+MATTER+OF+CEREBELLUM&source=images&cd=&cad=rja&docid=dNe-NEvJjMEM6M&tbnid=-yPgU5SbRG7KhM:&ved=0CAUQjRw&url=http://antranik.org/central-nervous-system-intro-to-brain-and-ventricles-medulla-oblongata-pons-mid-brain-and-cerebellum/&ei=Zy9QUZjlKsnCPOb-gYAP&bvm=bv.44158598,d.ZGU&psig=AFQjCNE2K78yIMy44Sp20Rw7-k-cOy6m1Q&ust=1364295884846382

7/42
Cerebellum has: 1) cortex cerebellar (grey
matter on periphery)
2) white matter core (having
deep cerebellar nuclei, 4 oneach side, from lateral tomedial side:
DENTATE, EMBOLIFORM,GLOBoSE & FESTIGEAL.(Lateral medial)
DEGF! (dont eat greasy food) EMBOLIFORM + GLOBoSE =
NUCLEUS INTERPOSITUS.
http://www.google.com/url?sa=i&rct=j&q=WHITE+MATTER+OF+CEREBELLUM&source=images&cd=&cad=rja&docid=dNe-NEvJjMEM6M&tbnid=-yPgU5SbRG7KhM:&ved=0CAUQjRw&url=http://antranik.org/central-nervous-system-intro-to-brain-and-ventricles-medulla-oblongata-pons-mid-brain-and-cerebellum/&ei=Zy9QUZjlKsnCPOb-gYAP&bvm=bv.44158598,d.ZGU&psig=AFQjCNE2K78yIMy44Sp20Rw7-k-cOy6m1Q&ust=1364295884846382http://www.google.com/url?sa=i&rct=j&q=cerebellar%20nuclei&source=images&cd=&cad=rja&docid=Mi9L9-tXiLYbOM&tbnid=5t_hdYTH06dRyM:&ved=0CAUQjRw&url=http://quizlet.com/5348748/neuro-unit-4-l2-flash-cards/&ei=5y1QUfeZDonbPPvEgbgJ&bvm=bv.44158598,d.ZGU&psig=AFQjCNFhGJfY-4B5cFH8nNb6MuMH_3aYLw&ust=1364295339558837

8/42
CEREBELLAR CORTEX:
3 LAYERS:
Outermostmolecular
layer (STELLATE CELLS,
BASKET CELLS).
2ndlayerpurkinje cells
layer (Single cell layer of
Flask shaped cells).
3
rd
later
granular layer

9/42

10/42
INTRINSIC FIBERS:
Pass between cerebellar
cortex & vermis.
Also pass from 1
cerebellar hemisphereto other.
They remain in the
cerebellum.

11/42
AFFERENT FIBERS:
2 TYPES:
CLIMBING FIBERS(come
from inferior olivary
nucleus)
MOSSY FIBERS(all the
other afferent fibers
except the climbing are
called Mossy fibers).

12/42
EFFERENT FIBERS:
Start as axons of Purkinje cells.
Most of these axons synapseonto deep nuclear cells.
From deep nuclear cells,efferent fibers arisego todifferent parts of CNS .
Only few purkinje fibers
bypass deep nuclear cellsgo to vestibular nuclei(theseare from vermis & flocculo-nodular lobe).

13/42

14/42
neuronal circuit in the cerebellum
There is a neuronal circuit incerebellum.
Millions of such functional units.
Each functional unitconsist of apurkinje cell & a deep nuclear
cell.
Climbing fibersgive collaterals,which synapse with deep nuclearcells.
collaterals from climbing fibers
excite deep nuclear cells.
Climbing fiberspass tomolecular layersynapse withdendrites of purkinje cells.

15/42
(cont) Mossy fiberscollateralssynapse with deepnuclear cells.
Mossy fibersgranular
layersynapse withdendrites of granule cell.
1 climbing fibercan synapsewithabout 10 purkinjecells.
1 mossy fibercan synapsewith 100s of granule cells.

16/42
(cont)
Excitatory cells:
deep nuclear cells
Granule cells
Inhibitory cells:
Purkinje cells
Basket cells
Golgi II cells
Stellate cells

17/42
http://www.google.com/url?sa=i&rct=j&q=INFERIOR+CEREBELLAR+PEDUNCLE+CONNECTIONS:&source=images&cd=&cad=rja&docid=0EbjyPcQ8qg3NM&tbnid=fr903MHbwVgL4M:&ved=0CAUQjRw&url=http://www.studyblue.com/notes/note/n/cerebellum/deck/841584&ei=3DFQUeirM4iHPau7gOgB&bvm=bv.44158598,d.ZGU&psig=AFQjCNENcrDPs9s0WT73fqnVFyRDvMnOpQ&ust=1364296506951151

18/42
http://www.google.com/url?sa=i&rct=j&q=INFERIOR+CEREBELLAR+PEDUNCLE+CONNECTIONS:&source=images&cd=&cad=rja&docid=0EbjyPcQ8qg3NM&tbnid=fr903MHbwVgL4M:&ved=0CAUQjRw&url=http://www.studyblue.com/notes/note/n/cerebellum/deck/841584&ei=3DFQUeirM4iHPau7gOgB&bvm=bv.44158598,d.ZGU&psig=AFQjCNENcrDPs9s0WT73fqnVFyRDvMnOpQ&ust=1364296506951151

19/42
CONNECTIONS OF CEREBELLUM THROUGH 3
PEDUNCLES:
AFFERENT
EFFERENT
Superior peduncle
midbrainMiddle peduncle
pons
Inferior peduncle
medulla

20/42
INFERIOR CEREBELLAR PEDUNCLE
CONNECTIONS:
AFFERENTS: Posterior spino-cerebellar
tract.
Vestibulo-cerebellar fibers
(from vestibular nuclei).
Reticulo cerebellar (fromreticular formation).
Olivo-cerebellar (from inferior
olivary nucleus).
EFFERENTS: Cerebello-vestibular
Cerebello-reticular

21/42
http://www.google.com/url?sa=i&rct=j&q=+CEREBELLAR+CONNECTIONS:&source=images&cd=&cad=rja&docid=Fy5hSEfHfIJMIM&tbnid=5VHt5uDK3v43gM:&ved=0CAUQjRw&url=http://www.dizziness-and-balance.com/anatomy/cerebellum.htm&ei=OTJQUZ2qPMjtOurDgYAC&bvm=bv.44158598,d.ZGU&psig=AFQjCNGCKaJG1mGeMT5fNUyqZD5MCiYoCg&ust=1364296619213544

22/42

23/42
MIDDLE PEDUNCLE:
Mainly AFFERENTS (Ponto-cerebellar fibers).
These fibers arise frompontine nuclei & crossover to opposite sidemiddle cerebellarpeduncle.
These fibers are part ofcortico-ponto-cerebellar pathway.

24/42
SUPERIOR PEDUNCLE:
AFFERENTS:
ventral spino-cerebellar
tract.
Rubro-cerebellar tract
(from red nucleus).
Tecto-cerebellar (fromtectum of midbrain).

25/42
EFFERENTS:
To Red nucleus,thento thalamic nuclei
then to Cerebralcortex.
To thalamus
to basal ganglia.

26/42
CEREBELLUM HAS RECIPROCAL
CONNECTIONS with
1) CEREBRAL CORTEX
2) RETICULAR FORMATION
3) VESTIBULAR NUCLEI 4) RED NUCLEUS

27/42
BASIC FUNCTION OF CEREBELLUM:
To control timing of:
1. turn-on signals to agonists & turn-off signals to
antagonists at the onset of a movement &
2. turn-off signal to agonists & turn-on signals to
antagonists at the end of a movement.
Basic disturbance in cerebellar diseaseATAXIA /
INCOORDINATION OF MOVEMENT.

28/42
FUNCTIONS OF CEREBELLUM:
Functionally divided into 3 parts:
1) lateral zone
2) intermediate zone
3) flocculo-nodular lobe & vermis.

29/42
LATERAL ZONE: FUNCTION
No body representation.
Also called cerebro-cerebellum(extensiveconnections with cerebral
cortex). Program & plan movement.
Plans, sequence & timing ofeach component ofmovement.
Smooth progress ofmovement, e.g, eating thecurry & bread (breadcurrymouth).

30/42
*cerebellum does notINITIATE movement BUTCOORDINATES it.
In cerebellar diseaselossof smooth progression ofmovements.
Extra motor predictivefunction.
Helps to access timing ofmovement.

31/42
INTERMEDIATE ZONE: FUNCTION
Also called spino-cerebellum, due toconnection with spinal cord.
Face & limbs are
represented. Coordination of movements
(distal part of limbs). Acts as a comparator.
Compares intended plan ofmovement with actuallyperformed movement.
In case of discrepancy,corrective signals are sent.

32/42
Cerebellum gets intendedplan of movement frommotor cortex& also fromred nucleus.
shows cerebral &cerebellar controlofvoluntary movementsinvolving especially
intermediate zone& itsassociated nucleusinterpositus.

33/42
It recieves informationactually performedmovements fromPROPRIOCEPTORS
through spino-cerebellar tracts.
Compared & correctedvia signals throughthalamic nuclei tomotor cortex.

34/42
Also controls: rate, range & direction of
movement.
Damping function.
Prevents pendular movements & tremors
(pendular knee jerk in case of disease)

35/42
Also controls very rapid movements like typing
(ballistic movements).
Also controls very rapid eye movement
(reading & when a person in a moving vehicle,
fixate the outside scene).

36/42
FUNCTION OF FLOCCOLONODULAR LOBE &
VERMIS:
Also called vestibulo-cerebellum due to connectionwith vestibular nuclei.
Controls posture &equilibrium.
Also concerned with motion
sickness. Controls stretch reflex &
muscle tone. Normal influence is facilitatory
on stretch reflex & muscletone.
From here purkinje nervefibersvest nuclei (bypassdeep nuclear cells)

37/42
CEREBELLAR DISEASE:
Involvement of cerebellar cortex & 1 or more
of deep cerebellar nuclei.
*No muscle paralysis & no sensory loss occurs.
(MCQ)

38/42
FEATURES OF CEREBELLAR DISEASE::
1) ATAXIA: Incoordinate movements due to defect in control of
RANGE, DIRECTION, RATE & TIMING of movement.
Asynergia (no synergism between agonists &
antagonists; normal synergism = when agonistscontract, antagonists relax).
2) DYSMETRIA & PAST POINTING: Inability to control range or extent of movement.
Dysmetriaalso manifest as past pointing. When patient tries to touch an objecthand
overshoots (past pointing).

39/42
3) ADIADOCOKINESIA /
DYSDIADOCOKINESIA:
Inability to perform RAPID, ALTERNATE, OPPOSITE
movement (rapid supination & pronation of arm).
4) DRUNKEN GATE / STAGGERING GATE:
Patient walks on a broad base.
SPECIFIC POSTURE: Head is rotated & flexedtowards the side of lesion.

40/42
5) SLURRED SPEECH: Due to dysarthria ( disordered articulation).
Incoordination of muscles of articulation.
Some words or syllables are spoken loud & others are
spoken in weak tone. Some are held for long period & some are spoken
short.
6) INTENTION TREMORS / ACTION TREMORS:
Absent at rest. Appear when patient performs some voluntary action.
Example of drinking water from a cup.

41/42
7) REBOUND PHENOMENON:
Patient cannot stop a movement abruptly.
Example of flexion of elbowmay hit his face.
8) DECOMPOSITION OF MOVEMENTS: Patient is not able to perform actions involving
simultaneous movement at more than 1 joint.
Movements are broken into components.
Loss of smooth progression of 1 movement toother.

42/42
9) NYSTAGMUS: Rhythmic rapid movement of eyeballs when eyes are
focused on 1 side.
Cerebellum has a damping function, which is
disturbed. 10) PENDULAR KNEE JERK:
Due to loss of damping function of intermediate zoneof cerebellum.
11) HYPOTONIA: Due to loss of excitatory action of cerebellum on
stretch reflex & muscle tone.

Lecture on PHYSIOLOGY of Cerebellum by Dr. Roomi

Documents

Physiology- Rhythmical Excitation of Heart by Dr. Mudassar.....

GIT Physiology CHAPTER NO 62 Guyton by Dr. Roomi

Using brain stimulation methods to probe the physiology of.....

Roomi No:11

1st Lecture on the Physiology of Adrenal Gland by Dr Roomi

Roomi No:08

2nd Lecture on Skeletal Muscle Physiology by Dr. Mudassar...

Physiology of Acid Base Balance by Dr. ROOMI

Physiology of ANS Lecture 1 by Dr. Mudassar Ali Roomi

Physiology of Skeletal Muscle by Dr. Roomi

Mawlana Jalaluddin Roomi

physiology of Cerebellum lec foe 2nd year by dr sadia...

Roomi No:09

صدق الله العظيم الاسراء اية 58....

3rd Lecture on Adrenal Physiology by Dr. Roomi

Lecture on the Physiology of Neuromuscular Junction (NMJ) by...