Cerebellum(Yuni)

8/12/2019 Cerebellum(Yuni)

1/24


2/24

The cerebellum , the second-largest part of the brain

The cerebellum is posterior to the medulla and pons & inferior to the

posterior portion of the cerebrum


3/24

In superior /inferior

views, the shape of

the cerebellum is

somewhat like a

butterfly

The centralconstricted area is the

vermis

The lateral is

cerebellar

hemispheres


4/24

The cortex of the vermisinfluences the movements of the long

axis of the body, namely, the neck, the shoulders, the thorax, theabdomen, and the hips.

Intermediate zone of the cerebellar hemisphereto control themuscles of the distal parts of the limbs, especially the hands andfeet.

The lateral zone of each cerebellar hemisphereappears to beconcerned with the planning of sequential movements of the entirebody and is involved with the conscious assessment of movementerrors

The flocculonodular lobeis the simplest part of the cerebellumand helps control balance and eye movements.


5/24

A deep groove

known as the

horizontal fissure

Each hemispheres

consists of lobes:

- Anterior lobe&PosteriorGovern

subconcious aspect

of skeletal muscle

movements

- Flocculonodular

lobecontributes

to equilibrium &

balance


6/24

Have 2 part :- superfisial layer

cerebellar cortex

(gray matter)

- deep layer

whitematter

.

The cerebellar cortex

has ridges called folia.

The white matter of the

medulla resembles a

branching tree and is

called the arbor vitae.


7/24

The nuclei of the cerebellum are located in

the deep inferior center of the white matter


8/24

Four masses of gray matter are

embedded in the white matter of the

cerebellum on each side of the

midline

From lateral to medial, these nuclei

are the dentate, the emboliform, theglobose, and the fastigial.

Intracerebellar nuclei


9/24

Intracerebellar nuclei

Fibers from the dentate, emboliform, and globose nuclei leave the cerebellum

through the superior cerebellar peduncle.

Fibers from the fastigial nucleus leave through the inferior cerebellar peduncle.


10/24

There is a small amount of white matter in the vermis; it closely

resembles the trunk and branches of a tree and thus is termed the arbor

vitae.

There is a large amount of white matter in each cerebellar hemisphere.

The white matter is made up of three groups of fibers:(1) intrinsic

(2) afferent

(3) efferent.


11/24

Do not leave the cerebellum but connectdifferent regions of the organ.

Some interconnect folia of the cerebellar cortex

and vermis on the same side; others connectthe two cerebellar hemispheres together.

Intrinsik

fibers

form the greater part of the white matter andproceed to the cerebellar cortex.

They enter the cerebellum mainly through theinferior and middle cerebellar peduncles.

Afferentfibers

constitute the output of the cerebellum

The axons of the neurons then leave thecerebellum

Efferentfibers


12/24

Climbing fibers

Mossy fibers

Purkinje fibers


13/24

The climbing fibers are the terminal

fibers of the olivocerebellar tracts

They are so named because they

ascend through the layers of the

cortex like a vine on a tree.

They pass through the granular layer

of the cortex and terminate in the

molecular layer by dividing

repeatedly.

Each climbing fiber wraps around

and makes a large number ofsynaptic contacts with the dendrites

of a Purkinje cell


14/24

A single Purkinje neuron makes

synaptic contact with only oneclimbing fiber.

However, one climbing fiber

makes contact with 1 to 10

Purkinje neurons.

A few side branches leave each

climbing fiber and synapse with

the stellate cells and basket

cells.


15/24

A single mossy fibermay stimulate

thousands of Purkinje

cells through the

granule cells


16/24

Pharmacologic research has suggested that the

excitatory climbing and mossy afferent fibers use

glutamate (gamma-aminobutyric acid [GABA])as

the excitatory transmitter on the dendrites of the

Purkinje cells.

Further research has indicated that other afferentfibers entering the cortex liberate norepinephrine and

serotonin at their endings that possibly modify the

action of the glutamate on the Purkinje cells.


17/24

Vestibulocerebellum

Spinocerebellum

Neo- orcerebrocerebellum


18/24

responsible for balance and gait

is connected to the fastigial nucleusVestibulocerebellum

concerned with coordinating theactivities of the limb musculature

connects with the interposednucleus (the globose andemboliform)

Spinocerebellum

involved with the overallcoordination of voluntary motoractivities and is also involved inmotor planning

connects to the dentate nucleus.

Neo- orcerebrocerebellum


19/24

Pathway Function Origin Destination

1)Corticopontocerebellar Conveyscontrol from

cerebral

cortex

Frontal,parietal,

temporal, and

occipital

lobes

Via pontine nucleiand mossy fibers

to cerebellar

cortex

2)Cerebro-olivocerebellar Conveys

control from

cerebral

cortex

Frontal,

parietal,

temporal, and

occipital

lobes

Via inferior olivary

nuclei and

climbing fibers to

cerebellar cortex

3)Cerebroreticulocerebellar Conveys

control fromcerebral

cortex

Sensorimotor

areas

Via reticular

formation


20/24


4)Anterior

spinocerebellar

Conveys

information from

muscles and

joints

Muscle

spindles,

tendon

organs, and

joint

receptors

Via mossy fibers

to cerebellar

cortex

5)Posteriorspinocerebellar

Conveysinformation from

muscles and

joints

Musclespindles,

tendon

organs, and

joint

receptors

Via mossy fibersto cerebellar

cortex

6) Cuneocerebellar Conveys

information from

muscles and

joints of upper

limb

Muscle

spindles,

tendon

organs, and

joint

receptors

Via mossy fibers

to cerebellar

cortex


21/24


7)Vestibular nerve Conveys

information of

head position

and

movement

Utricle,

saccule,

and

semicircul

ar canals

Via mossy fibers

to cortex of

flocculonodular

lobe

8)Other afferents Conveys

informationfrom midbrain

Red nucleus,

tectum

Cerebellar cortex


22/24


Globose-

emboliform-

rubral

Influences

ipsilateral

motor

activity

Globose and

emboliform

nuclei

To contralateral red

nucleus, then via

crossed rubrospinal

tract to ipsilateral

motor neurons in

spinal cord

Dentothalamic Influencesipsilateral

motor

activity

Dentatenucleus

To contralateralventrolateral nucleus

of thalamus, then to

contralateral motor

cerebral cortex;

corticospinal tract

crosses midline andcontrols ipsilateral

motor neurons in

spinal cord


23/24

Note that each cerebellar hemisphere influences the voluntary muscle tone on

the same side of the body.

Pathway Function Origin DestinationFastigial

vestibular

Influences

ipsilateral

extensor muscle

tone

Fastigial

nucleus

Mainly to ipsilateral

and to contralateral

lateral vestibular

nuclei; vestibulospinal

tract to ipsilateral

motor neurons inspinal cord

Fastigial reticular Influences

ipsilateral muscle

tone

Fastigial

nucleus

To neurons of

reticular formation;

reticulospinal tract to

ipsilateral motorneurons to spinal

cord


24/24

Cerebellar PedunclesThe cerebellum is linked to other parts of the central nervous system by

numerous efferent and afferent fibers that are grouped together on each side into

three large bundles, or peduncles.

The superior cerebellar peduncles connect the cerebellum to the midbrainThe middle cerebellar peduncles connect the cerebellum to the pons

The inferior cerebellar peduncles connect the cerebellum to the medulla

oblongata.

Cerebellum(Yuni)

Documents