6.5b cerebellum
DESCRIPTION
cerebellumTRANSCRIPT
The Cerebellum
Patient with Cerebellar Problem
Objectives:
Explain the clinical manifestations of cerebellar dysfunction based on the:
a. Structure/s affectedb.Cerebellar cortex circuitry affectedc. Pathway/s involved
Cerebellum:
Vermis
Cerebellar hemispheres
Sulci/fissures
Cerebellar Peduncles & Connections
• Superior (brachium conjunctivum) midbrain
• Middle (brachium pontis) pons
• Inferior (restiform body) medulla
* juxtarestiform body- medial part
Cerebellum:• Coordination of voluntary muscle activity
• Equilibrium
• Muscle tonus
Each cerebellar hemisphere controls muscular movements on the same side of the body.
ESM
The cerebellum has no direct PW to the LMN’s exerts its control via the cerebral cortex and the brainstem…
Does NOT initiate movement
X- Coordination of eye and limb mov’ts. slow,
tremulous, and uncoordinated
The cerebellum has no direct PW to the LMN’s exerts its control via the cerebral cortex and the brainstem…
X- Movement
X- Muscle tone and posture hyper- or hypotonic; cannot stand
or walk w/o swaying
3 Main Lobes: (transverse divisions)
1.) Paleocerebellum/Anterior lobe
- input: spinocerebellar and trigeminocerebellar PW’s
- stance and gait
2.) Neocerebellum/Middle lobe/Posterior Lobe
-input: cerebral cortex
- speech and coordinated movement
3.) Archicerebellum- flocculonodular lobe (oldest)
- input: vestibular nuclei
- equilibrium (balance, posture, eye movements)
/nodulus Posterolateral fissure
Lobes of the Cerebellum
Lobes of Cerebellum: Function
Cortex…
White matter
Folium & Arbor Vitae
Junqueira’s Basic Histology Text and Atlas 12th ed. Anthony L. Mescher, The
McGraw-Hill Companies, Inc.
Intracerebellar nuclei
Interposed nuclei
Cerebellar Cortex:Cell Layers
Cortex: Gray Matter
3 Layers
Basket celldendrites and axons
Molecular Layer:
Stellate cell
Cerebellar Cortex: Layers
Purkinje Cell Layer:
- Golgi Type I
- flask-shaped
- one layer
Purkinje Cell Layer
Purkinje Cell Layer:
Junqueira’s Basic Histology Text and Atlas 12th ed. Anthony L. Mescher, The
McGraw-Hill Companies, Inc.
Purkinje Cell Layer:
Myelin sheath
Granular Layer:
Granule cell
Golgi type II cell
Glomeruli or cerebellar islands- mossy fiber rosette (center)
Granular Layer
Cerebellar Circuitry
Cerebellar Circuitry
Cerebellar Circuitry
SummarySpinal cord, pontine nuclei, Inferior OliveVestibular nuclei & ganglia, Trigeminal nuclei, reticular formationNuclei & Deep cerebellar nuclei
Mossy Climbing
Granule Cell Layer Molecular Layer/Dendrites of Purkinje Cells
Efferent: Purkinje cells
(+)
glutamate
(+)- Excitatory
(-)- Inhibitory
Climbing fiber Glutamate/ aspartate
Inferior olive
Mossy fiber Glutamate, ACh
(+)
(+)
(+)(+)
Cerebellar Cortex Circuitry:
(-)
(-)
(-)
(-)
(+)- Excitatory
(-)- Inhibitory
GABA
GABA
GABA
Inferior olive
GABA(-)
(-)
(-)(-)
Cerebellar Cortex Circuitry:
(-)
(+)(-)
(-)
(-)
glutamate
(+)- Excitatory
(-)- Inhibitory
Climbing fiber Glutamate/ aspartate
GABA
GABA
GABA
Inferior olive
Mossy fiber Glutamate, ACh
GABA (+)
(+)
(-)
(-)
(-)
(+)(+)
(-)
Cerebellar Cortex Circuitry:
Cerebral Peduncles:Afferent & Efferent Fibers
Peduncle Afferent Tracts Efferent Tracts
Superior -Anterior spinocerebellar-Trigeminocerebellar (some)
-Dentatorubral-Dentatothalamic-Dentatoreticular
Middle -Pontocerebellar
Inferior -Posterior spinocerebellar-Cuneocerebellar-Reticulocerebellar-Olivocerebellar-Trigeminocerebellar (some)-Vestibulocerebellar
- Fastigiobulbar
Connections of the Cerebellum
Cerebellar Afferent Fibers:• From the cerebral cortex
Pathways/tracts:- corticopontocerebellar- cerebro-olivocerebellar- cerebroreticulocerebellar
Important in the control of voluntary movement;
initiation of movement
Cerebellar Afferent Fibers:
Corticopontocerebellar PW
Information from:
1° motor and sensory areas and associative areas
1° visual cortex
Pontine nuclei
Cerebellar Afferent Fibers:
Cerebro(cortico)-olivocerebellar PW
climbing fibers
Information:
Motor area
Inf. olivary nucleus
Cerebroreticulocerebellar PW
Cerebellar Afferent Fibers:
Information:
Motor areas
paravermal regions
reticular formation
pons and medulla
Cerebellar Afferent Fibers:• From the spinal cord
- anterior spinocerebellar- posterior spinocerebellar- cuneocerebellar
- Information is sent from the somatosensory receptors
Cerebellar Afferent Fibers:
From the vestibular nerve flocculonodular lobe
Receive information from the inner ear:
motion
position
• Vestibulocerebellar:
Cerebellar Afferent Fibers:
From the vestibular nerve
All afferent fibers terminate in the
flocculonodular lobe
vestibular nuclei
Table 6-1 The Afferent Cerebellar Pathways:
Pathway: Function: Origin: Destination:
Corticoponto-cerebellar
Conveys control from cerebral cortex
Cerebral lobes Via pontine nuclei and mossy fibers to cerebellar cortex
Cerebro-olivocerebellar
Via inf. olivary nuclei and climbing fibers to cerebellar cortex
Cerebroreticulo-cerebellar
Sensorimotor areas
Via reticular formation
Ant. and Post. spinocerebellar
Conveys information from muscles and joints
Muscle spindles, tendon organs, and joint receptors
Via mossy fibers to cerebellar cortex
Cuneo-cerebellar
Conveys info. from ms. and jts. of UL
Vestibular nerve Conveys information of head position and movement
Utricle, saccule, and semicircular canals
Via mossy fibers to cortex of flocculonodular lobe
Other afferents Conveys information from midbrain
Red nucleus, tectum
Cerebellar cortex
Synthesis….Questions
1. Input from the inferior olivary nucleus enters the cerebellar cortex circuitry as ______ fibers.
2. Afferents synapsing at the pontine nuclei will give rise to transverse fibers that will synapse with cerebellar cortex thru ______ cerebellar peduncle.
3. _________ lobe of the cerebellum receives input from the vestibular nuclei.
Entire output
most axons
Cerebellar Efferent Fibers:
Red nucleus
Thalamus
Vestibular complex
Reticular formation
Cerebellar Efferent Fibers:• Globose-Emboliform-Rubral Pathway• Dentothalamic PW• Fastigial Vestibular PW• Fastigial Reticular PW
* Decussation of the superior cerebellar
peduncle
Globose-Emboliform-Rubral
PW
Influences ipsilateral motor
activity
rubrospinal tract
VL nucleus thalamus
1° motor area cerebral cortex
Influences ipsilateral motor
activity
Dentothalamic PW
corticospinal fibers
decussation of pyramid
lateral vestibular nucleus Fastigial vestibular PW
Influences ipsilateral extensor muscle tone
vestibulospinal tract
Fastigial Reticular PW
reticulospinal tract
reticular formationInfluences ipsilateral
muscle tone
Table 6-2 The Efferent Cerebellar Pathways:
Pathway: Function: Origin: Destination:
Globose-emboliform-rubral
Influences ipsilateral motor activity
Globose emboliform nuclei
To CL red nucleus, then via crossed rubrospinal tract to ipsilateral motor neurons in spinal cord
Dentothalamic Influences ipsilateral motor activity
Dentate nucleus
To CL VL nucleus of thalamus, then to CL motor cerebral cortex; corticospinal tract crosses midline and controls ipsilateral motor neurons in spinal cord
Fastigial vestibular
Influences ipsilateral extensor muscle tone
Fastigial nucleus
Mainly to ipsilateral and to CL lateral vestibular nuclei; vestibulospinal tract to ipsilateral motor neurons in spinal cord
Fastigial reticular
Influences ipsilateral muscle tone
Fastigial nucleus
To neurons of reticular formation; reticulospinal tract to ipsilateral motor neurons to spinal cord
Functional Areas of the Cerebellar Cortex:
(sagittal divisions)
vermis
int
zone
lateral
zone
Vermal flocculonodular z.:Vermis/
Functional Areas of the Cerebellar Cortex:
(sagittal divisions)
vermis
int
zone
lateral
zone- control of posture, muscle
tone, locomotion, equilibrium
- projects to the fastigial nucleus
Vermal flocculonodular z.:Vermis/
Damage: ataxia
Functional Areas of the Cerebellar Cortex:
(sagittal divisions)
vermis
int
zone
lateral
zone
Paravermal/
Intermediate Zone:
Functional Areas of the Cerebellar Cortex:
(sagittal divisions)
vermis
int
zone
lateral
zone
Paravermal/
Intermediate Zone:
- Projects to nucleus interpositus
Damage:
Wide-based stance
Walking: stagger
Functional Areas of the Cerebellar Cortex:
(sagittal divisions)vermis
int
zone
lateral
zone
Lateral Zone:
- dentate nuclei thalamus motor cortex pontine nuclei, spinal cord (ant. horn cells)
Functional Areas of the Cerebellar Cortex:(sagittal divisions)
Lateral Zone:• coordination of
ipsilateral somatic motor activity
• planning of movement
• assessment of errors* Projects to the dentate
nucleus
Functional Areas of the Cerebellar Cortex:
(sagittal divisions)vermis
int
zone
lateral
zone
Lateral Zone:Lesions: cerebellar incoordination (asynergia)
Dysmetria
Past-pointing
Tremor
Dysdiadochokinesis- inability to perform regular/ rapidly alternating movements
Rebound phenomenon
Feedback Loop/s:Cortico-ponto-cerebello-dentato-
thalamo-cortical PW
(Major and Most Important)
Cerebellar Afferent Fibers:
Corticopontocerebellar PW
Information from:
1° motor and sensory areas and associative areas
1° visual cortex
Pontine nuclei
VL nucleus thalamus
1° motor area cerebral cortex
Influences ipsilateral motor
activity
Dentothalamic PW
corticospinal fibers
decussation of pyramid
Neurologic Exam: Cerebellum
Origin:
cerebral cortex
muscles, tendons, and
joints
vestibular nerve
(few)
(most)
Cerebellar Cortical Circuitry: In summary…
(few)
(most)
Inhibitory influence
lateral vestibular nucleus
Cerebellum- NO DIRECT neuronal connections with
LMN’s
- INDIRECT
Cerebellum- coordinator of precise movements
- bring about the necessary adjustments
- influence activity of LMN’s
(motor area)
Cerebellum- send back information
inhibit agonist muscles; stimulate antagonist ms.
limits voluntary movement
(motor area)
Manter and Gatz’ Essentials of Clinical Neuroanatomy and Neurophysiology 10th ed. Sid Gilman, MD, FRCP, Sarah Winans Newman, PhD; F.A. Davis Publishers Philadelphia
Clincal Neuroanatomy 7th ed., 2010
Richard S. Snell
Wolters Kluwer/Lippincott Williams and Wilkins
Lansang Notes: Modules in Anatomy 4th ed. Esperanza N. Carague-Lansang, MD, Ma. Cristina S. Elma, MD, Luis Emmanuel O. Esguerra, MD
Junqueira’s Basic Histology Text and Atlas 12th ed. Anthony L. Mescher, The McGraw-Hill Companies, Inc.
Thank you…