Cerebellum Cerebellum External External ConfigurationsConfigurations

- located in - located in posterior cranial fossaposterior cranial fossa- tentorium cerebelli (cerebrum), 4th ventricle (brain - tentorium cerebelli (cerebrum), 4th ventricle (brain stem)stem)- communicate with other structure via- communicate with other structure via superior, middle, and inferior cerebellar pedunclesuperior, middle, and inferior cerebellar peduncle

- - longitudinal divisionlongitudinal division Vermis, Paravermal Region, Cerebellar HemisphereVermis, Paravermal Region, Cerebellar Hemisphere

- - transverse divisiontransverse division Anterior LobeAnterior Lobe ------------ ------------ primary fissureprimary fissure Posterior LobePosterior Lobe ------------ ------------ posterolateral fissureposterolateral fissure Flocculonodular Lobe Flocculonodular Lobe

F. The cerebellum- Has two lobed hemispheres that connect via the vermis. It has outer gray matter, imbedded white matter and deep gray matter (nuclei). Its surface ridges are called folia and they are separated by fissures. It coordinates movement and makes it smooth, it helps in maintaining posture and equilibrium and is involved in cognition.

Spinocerebellum

Pontocerebellum

Vestibulocerebellum

1. Purkinje cell

2. granule cell

3. basket cell

4. Golgi cell

5. stellate cell

6. climbing fiber

7. mossy fiber

8. parallel fiber

9. inferior olivary nucleus

10. deep cerebellar nuclei

Afferent ConnectionsAfferent Connections (1): (1):

Cerebellum Cerebellum ConnectionsConnections

Vestibulocerebellar fiber linkage

• maintain the body’s balance and regulate ocular movement.

vestibular nucleiinferior cerebellar peduncle flocculonodular

lobe

medical longitudinal fasciculus

motor neuron of extraocular muscles

vestibulospinal tract

motor neuron of trunk muscle

Superior Cerebellar Superior Cerebellar PedunclePeduncle

Anterior Spinocerebellar Anterior Spinocerebellar TractTract

Cerulocerebellar fiberCerulocerebellar fiber Raphecerebellar fiberRaphecerebellar fiber Rubrocerebellar fiberRubrocerebellar fiber

Hypothalamocerebellar Hypothalamocerebellar fiberfiber

control muscular tension and regulate muscular movement

Spinicerebellar fibra links and function

direct cerebellar tractinferior cerebellar pedunclesuperior cerebellar peduncle

vermis

fastigial nucleus

intermedial nucleus

cortex of cerebellar hemisphere

red nucleus of opposite side rubrospinal tract

zona rolandica lateral corticospinal tract

vestibular nucleusreticular formation of brain stem

vestibulospinal tract

reticulospinal tract

• dominate the planning and coordination of refined movement of limbs

The fibra links and function of cerebrocerebellum

extensive area of cerebral cortex pontine nucleus

lateral part cortex of cerebellar hemisphere

dentate nucleus

red nucleus

ventrolateral nucleus of dorsal thalamus zona rolandica

lateral corticospinal tract

rubrospinal tract

Efferent ConnectionsEfferent Connections : :

1. Superior Cerebellar Peduncle1. Superior Cerebellar Peduncle

Cerebellothalamic fiberCerebellothalamic fiber - from 3 deep nuclei to VPLo, VLc, CL- from 3 deep nuclei to VPLo, VLc, CL

Cerebellorubral fiberCerebellorubral fiber - from nucleus interpositus - from nucleus interpositus and dentate nucleusand dentate nucleus 2. Inferior Cerebellar Peduncle2. Inferior Cerebellar Peduncle

Fastigiovestibular fiberFastigiovestibular fiber

Cerebellum Cerebellum ConnectionsConnections

Two types of fibers to cerebellar cortex                              1.         Climbing fibers                                    a,         project to dendritic trees of Purkinje neurons                                    b.         are extremely excitatory                        c.         primarily originate from inferior olivary nucleus may be some contribution from pontine and reticular nuclei

                        2.         Mossy fibers                                    a.         much more numerous than climbing fibers                                    b.         origination is spinocerebellar and pontocerebellar                                    c.         project to granule cell dendrites             d.         from granule cells, information is passed to dendritic branches of Purkinje cells.                                    e.         are extremely excitatory

Climbing and Mossy fibers are part of a circuit

                        1.         excitatory input enters, is integrated throughout cells of cerebellar cortex, exits via axons of Purkinje cells

                        2.         outflow is inhibitory

                        3.         primary target of cerebellar outflow is deep cerebellar nuclei                                    a.         globose and emboliform axons project to red nucleus & reticular formation via superior cerebellar  peduncles, then to cord via rubrospinal tract.

                                    b.         dentate axons project to thalamus via superior cerebellar peduncles, and then to cerebral cortex

                                    c.         fastigial axons project to vestibular nuclei and nuclei for cranial nerves III, IV, and VI via inferior cerebellar peduncles

CerebellumCerebellum FunctionFunction

Maintenance of EquilibriumMaintenance of Equilibrium - balance, posture, eye movement - balance, posture, eye movement

Coordination of half-automatic movement ofCoordination of half-automatic movement of walking and posture maintenacewalking and posture maintenace - posture, gait - posture, gait

Adjustment of Muscle ToneAdjustment of Muscle Tone

Motor Leaning – Motor SkillsMotor Leaning – Motor Skills

Cognitive FunctionCognitive Function

BalanceBalance

Motor Skill Motor Skill

Pablo CasalsPablo Casals

PosturePostureGait – AtaxiaGait – Ataxia

TremorTremor

Cerebellar Cerebellar AtaxiaAtaxia

Ataxic gait and Ataxic gait and position: position: Left cerebellar tumorLeft cerebellar tumor

a. Sways to the right ina. Sways to the right in standing positionstanding position

b. Steady on the b. Steady on the right legright leg

c. Unsteady on the c. Unsteady on the left legleft leg

d. ataxic gaitd. ataxic gait

a b c

d

Cerebellar tumors on Cerebellar tumors on vermisvermis

- Truncal Ataxia- Truncal Ataxia - Frequent Falling- Frequent Falling

The child in this picture:The child in this picture:

- would not try to stand - would not try to stand unsupportedunsupported - would not let go of the bed rail- would not let go of the bed rail if she was stood on the floor.if she was stood on the floor.

Cerebellar Cerebellar MedulloblastomaMedulloblastoma