Upload
ps-deb
View
9.006
Download
11
Tags:
Embed Size (px)
DESCRIPTION
Clinical anatomy and physiology or cerebellum
Citation preview
CEREBELLUM
Dr PS Deb MD, DM (Neuro)
GNRC Hospitals Guwahati, Assam, India
SCHEMATIC REPRESENTATION OF THE MAJOR ANATOMICAL SUBDIVISIONS OF THE CEREBELLUM.
PHYLOGENETIC ORGANIZATION
Spinocerebellum
Pontocerebellum
Vestibulocerebellum
DEVELOPMENT OF CEREBELLUM
Archicerebellum (nodulus)
Archicerebellum (flocculus)
Paleocerebellum
Neocerebellum
FUNCTIONAL ORGANIZATION OF CEREBELLUM
FUNCTIONAL AND PHYLOGENETIC ROLE
Phylogenetic denomination
Anatomical parts Role
Vestibulocerebellum (Archicerebellum)
Flocculonodular lobe (+ adjacent vermis)
Regulates balance and eye movements.
Spinocerebellum (Paleocerebellum)
Vermis and intermediate parts of the hemispheres ("paravermis")
regulates body & limb movements.The spino cerebellum is able to elaborate proprioceptive input in order to anticipate the future position of a body part during the course of a movement.
Cerebrocerebellum (Neocerebellum)
Middle portion of the vermis & Lateral parts of the hemispheres
involved in planning & initiation of movement.It has purely cognitive functions as well.
CEREBELLAR NUCLEUS
Dentate n. Emboliform n.
Globose n. Fastigial n.
FUNCTION OF CEREBELLAR NUCLEUS The fastigial nucleus assists stance & gait &
controls muscles only in the modes of sitting,standing & walking.
The nucleus interposed assists segmental reflexes & speeds the initiation of movement triggered by somatosensory cues.
The dentate nucleus assists in tasks requiring fine dextirity.
MOTOR MODULATION BY THE CEREBELLUM
INPUT OF CEREBELLUM
CEREBELLAR OUTPUT
VESTIBULOCEREBELLUM
THE SPINOCEREBELLUM CONTAINS TWO SOMATOTOPIC NEURAL MAPS OF THE BODY
NEOCEREBELLUM
NEURONAL CITCUITS OF CEREBELLUM
CEREBELLAR PATHWAY
Peduncle Description
SUPERIOR some afferent fibers from the anterior spinocerebellar pass to the anterior cerebellar lobe via this peduncle. Thus, the superior cerebellar peduncle is the major output pathway of the cerebellum. Most of the efferent fibers originate within the dentate nu.which in turn project to various midbrain structures including the red nucleus, the ventral lat./ventral ant. nucleus of the thalamus, and the medulla. The dentatorubrothalamo cortical& cerebellothalamocortical pathways are two major pathways that pass through this peduncle and are important in motor planning.
MIDDLE This is composed entirely of afferent fibers originating within the pontine nuclei as part of the massive corticoponto cerebellar tract.These fibers descend from the sensory and motor areas of the cerebral neocortex and make the middle cerebellar peduncle the largest of the three cerebellar peduncles.
INFERIOR Proprioceptive information from the body is carried to the cerebellum via the dorsal spinocerebellar tract. This tract passes through the inferior cerebellar peduncle and synapses within the paleocerebellum. Vestibular information projects onto the archicerebellum.The climbing fibers of the inferior olive run through the inferior cerebellar peduncle.This peduncle also carries information from the Purkinje cells to the vestibular nuclei in the dorsal brainstem located at the junction between the pons and medulla
Tracts or fiber bundles Distribution
Inferior cerebellar peduncle
Afferent paths Olivocerebellar tract
Lateral hemispheres and
cerebellar nucleus
Paraolivocerebellar tract Vermis, paravermis. and
cerebellar nucleus
Vestibulocerebellar tract
Fastigial nucleus, flocculonodular lobe, and uvula
Reticulocerebellar tract Spinal region of cerebellar
vermis
Posterior spinocerebellar tract Hind limb region of cerebellar
cortex
Trigeminocerebellar tract Dentate and emboliform
nucleus
Cuneocerebellar tract Forelimb and upper trunk region of cerebellar cortex
Anterior exterior arcuate fibers Flocculus
Arcuatocerebellar fibers (striae
medullares) Flocculus
Efferent paths Cerebellovestibular tract Vestibular nucleus
Cerebelloreticular tract Pontine and medullary
reticular nucleus
CEREBELLAR CONNECTIONS--
Middle cerebellar peduncle
Afferent paths Pontocerebellar tract Neocerebellar cortex
Superior cerebellar peduncle
Afferent paths
Anterior spinocerebellar tract Hind limb region of cerebellar
cortex
Tectocerebellar tract Intermediate vermis and
lobulus simplex
Trigeminocerebellar tract
Efferent paths
Dentatorubral fibers Red nucleus
Dentatothalamic fibers
Ventral intermediate (VI) and
ventral anterior (VA) nucleus
of thalamus
Fastigioreticular fibers Reticular nucleus of midbrain,
pons, and medulla oblongata
CONT.
Afferent connection
MAIN CONNECTIONS OF THE VESTIBULOCEREBELLUM
Floculonodular
Lobe
Vermis
FASTIGIAL NUCLEUS
VESTIBULAR NUCLEUS
Vestibular Organ
lower motor neuron LMN
ARCHICEREBELLUM
vestibulospinal tract
MLF
RED NUCLEUS
MAIN CONNECTIONS OF THE PALEOCEREBELLUM
RED NUCLEUSNUCLEUS
INTERPOSITUS
ANTERIOR LOBE
PARAVERMAL ZONE
PALEOCEREBELLUM
Inferior OlivryNucleus
Lower motor neuronSPINAL CORD
Rubrospinal tract
spinocerebellar tract
MAIN CONNECTIONS OF THE NEOCEREBELLUM
CEREBRAL CORTEX THALAMUS
PontineNucleus
Lower motor neuron
LMN
DENTATENUCLEUS
POSTERIOR LOBE
CEREBELLAR HEMISPHERE
NEOCEREBELLUM
Pyramidal tract
CEREBELLUM AND AUTOMATIC MOTOR CONTROL
CEREBELLUM
MOTOR CORTEX
RED NUCLEUS
VESTIBULAR
NUCLEUS
RETICULAR FORMATION
LOWER MOTOR NEURONProprioceptor
s
Corticonuclear Connections
A zone ---------- fastigial nucleus medial vestibular nucleus B zone ---------- lateral vestibular nucleus
C1, C3 zone --- emboliform nucleus C2 ---------------- globose nucleus
D1 ---------------- parvocellular portion of dentate nucleus D2 ---------------- magnocellular portion of dentate
nucleus
VOOGD ORIGINALLY DESCRIBED 4 ZONES, FROM MEDIAL TO LATERAL--
1. vermis
2. paravermal region
3. cerebella hemisphere
4. nodulus
5. flocculus
6. fastigial nucleus
7. globose nucleus
8. emboliform nucleus
9. dentate nucleus
10. medial vestibular
nucleus
11. lateral vestibular
nucleus
The inferior olivary nucleus or inferior olive comprises 3 major divisions –
the principal olive (PO), the dorsal accessory olive (DAO) and the medial accessory olive (MAO). Different divisions of the olive project to
different cortical zones. The inferior olive is the only source of climbing fibre inputs to the cerebellum. Inputs from all other sources are as mossy fibres.
Olivocerebellar Connections
Caudal portion of medial and dorsal accessory olivary nucleus ----------------- vermis of cerebellar cortex (A and B) fastigial nucleus vestibular nucleus
Rostral portion of medial and dorsal accessory olivary nucleus ----------------- paravermal region (C1, C2, C3) nucleus interpositus
Principal Inferior Olivary Nucleus ----------------- cerebellar hemisphere (D1, D2) dentate nucleus
Caudal portion
Rostral portion
Principal inferior olivary nucleusmedial and dorsal accessory olivary nucleus
The posterior inferior cerebellar artery (PICA): supplies-
Lat.medullary tegmentum, inferior cerebellar peduncle The ipsilat.portion of the inferior vermis & the inferior surface of the cerebellar
hemisphere. The medial br. of the PICA supplies the
medial cerebellum & the dorsolat. Medulla oblongata.
The lateral br.supplies the inferoposterolat. aspect of the cerebellum.
VASCULAR SUPPLY OF THE CEREBELLUM:
CEREBELLAR CIRCULATION
Maintenance of Equilibrium - balance, posture, eye movement
Coordination of half-automatic movement of walking and posture maintenace - posture, gait
Adjustment of Muscle Tone
Motor Leaning – Motor Skills
Cognitive Function
CEREBELLUM:FUNCTIONS
April 1
1, 2
02
3
ARCHICEREBELUM
Floculonodular lobe- Vestibulocerebelum Function:
Maintenance of equilibrium Suppress Vestibulo Ocular Reflex Muscle tone in relation to head posture
Animal ablation Disorder of equilibrium Positional nystagmus
Human: Meduloblastoma Trunkal ataxia Vestibular nystagmus (fast component towards the
side of lesion) Positional nystagmus does not fatigue Vertigo
April 1
1, 2
02
3
PALLEO-CEREBELUM Anterior lobe + Vermis Afferent:
Spinocerebellar tract Spino-> olivo->cerebellar Spino -> reticulo ->
cerebellar Efferent
Festigio -> vestibulo -> spinal
Festigio -> Reticulo -> Spinal
Function Tone control Posture of axial muscle Equilibrium and locomotion
Animal ablation Increased lengthening
and shortening Increased tendon reflex Exagerated postural
reflex (positive supporting reflex)
Human Alcoholic degeneration Cerebellar degeneration Gait ataxia Rarely mild hypotonia,
dysmetria and dysarthria
April 1
1, 2
02
3
NEOCEREBELUM
Ablation in Dog and Cat inconstant result Monkey ablation
Hypotonia Clumsiness of ipsilateral limb Dentate nucleus ablation -> more enduring
effect intension tremor
April 1
1, 2
02
3
CEREBELLAR ZONES
1. Vermis zone: control posture, tone, locomotion, equilibrium
i. Vestibular connection project to festigial nucleusii. Control position of the head in relation to trunk and
extraocular movments
2. Intermediate zonei. Affrent-
a. proprioceptive from limbb. Sensorimotor cortexc. Collateral from corticospinal tract
ii. Efferent globos and embodiform nucleus ->VL thalamus to motor cortex
iii. Function: Regulation of movment via sensory feedback from the corticospinal muscle
a. Control velocity, force, pattern of movement
April 1
1, 2
02
3
CEREBELLAR ZONES: LATERAL Afferent: motor and sensory association cortex Efferent: Dantate -> thalamus -> motor cortex
(open loop) Function: Programing of movement before initiation Animal: coordination of ipsilateral movment Human: Hypotonia- flabby muscle, abnormal
posture (slopping of shoulder) increased excursion of outstretched hand tapping. Hyperflexibility of joint, pendular reflex knee
Cerebellum control separately the activity of alpha and gamma motor neuron
Reduced fusimotor activity from abnormal long loop reflex through precentral cortex
April 1
1, 2
02
3
CEREBELLAR DYSFUNCTION
1. Ataxia: Limb, gait and speech2. Speech: Scanning3. Tremor: Postural, intention, limb, trunk and
head4. Tone: Hypotonia -> Hyperextensibility, pendular
knee jerk, rebound phenomenon5. Voluntary movement: Dysmetria, dysynergia,
disdidokokinesia6. Gait: ataxic, truncal ataxia7. Head tilt8. Postural abnormality: due to unequal hypotonia
of truncal muscle -> scoliosis, elevation or depression of shoulder, pelvic tilt
April 1
1, 2
02
3
VOLUNTARY MOVEMENT ABNORMALITY
Gorden Holms : Rate, range and force Dyssynergia: Disruption of the normal smooth control
of movement provided by gradual contraction of synergic muscle and relaxation of their antagonist
Voluntary movement- longer to start and longer to stop
Prolongation of interval between the command and triphasic agonist- antagonist and motor sequence
Agonist burst may be too long or short or continue into the antagonist burst -> dysmetria and dysenergia
Rebound phenomenon (abnormal check reflex) Dysdiadokokinesia Decomposition of movement
Scanning speech Cogwheel eye moevment
April 1
1, 2
02
3
VOLUNTARY MOVEMENT ABNORMALITY
Dysmetria Inability of the sensorimotor apparatus to measure
distance in the course of movement Hypometria and hypermetria of the limb and eye Tremor : Postural and intention Ataxia of gait: falling towards the side of lesion Nystagmus:
Gaze paretic (evoked) deviation Downbeat Rebound Sustained horizontal Opsoclonus Skew deviation
Weakness, faitibability and loss of associted movement
THANKS