The Anatomy of the Cerebellum: External and Internal Features
Prof. Ahmed Fathalla Ibrahim
Prof. Ahmed Fathalla Ibrahim
Prfessor of Anatomy
Prfessor of Anatomy
Dr. Sanaa Alshaarawy
Dr. Sanaa Alshaarawy
Associate Professor of
Associate Professor of
Anatomy
Anatomy
OBJECTIVES
OBJECTIVES
At the end of the lecture, students should:
At the end of the lecture, students should:
Describe
the External features
of the cerebellum
(lobes, fissures).
Describe briefly
the Internal structure
of the
cerebellum.
List the name of
Cerebellar Nuclei.
Relate
the Anatomical to the Functional
Subdivisions
of the cerebellum.
Describe
the Important connections
of each
subdivision.
Describe briefly the
Main Effects
in case of
lesion
of the cerebellum.
CEREBELLUM
•
ORIGIN :
ORIGIN :
•
From Hindbrain.
•
Position :
•
lies behind
Pons
&
Medulla
Separated
from them by
Fourth ventricle.
THE CEREBELLUM
THE CEREBELLUM
CONNECTION TO BRAIN
CONNECTION TO BRAIN
STEM:
STEM:
by
Inferior
,
Middle
&
Superior
Cerebellar
Peduncles.
EXTERNAL FEATURES
EXTERNAL FEATURES
It consists
of
two
Cerebellar
Hemispheres
joined in
midline by the
Vermis.
Its surface
is highly
convoluted forming
Folia
,
separated by
Fissures.
ANATOMICAL SUBDIVISION
ANATOMICAL SUBDIVISION
1.
Anterior lobe
Anterior lobe
:
:
in front
of
primary fissure,
on the superior surface.
2.
Posterior (middle) lobe
Posterior (middle) lobe
:
:
behind
primary fissure
(
Between
Primary & Secondary
fissures = posterolateral).
3.
Flocculonodular lobe
Flocculonodular lobe
:
:
in front
in front
of secondary (Posterolateral) fissure,
of secondary (Posterolateral) fissure,
on the
on the
inferior surface .
inferior surface .
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ANATOMICAL SUBDIVISION
ANATOMICAL SUBDIVISION
Secondary Fissur
Or
CONSTITUENTS
CONSTITUENTS
(Internal Structure and Nuclei of Cerebellum)
(Internal Structure and Nuclei of Cerebellum)
1.
Outer grey matter:
Outer grey matter:
cerebellar
cortex.
2.
Inner white matter:
Inner white matter:
cerebellar
medulla.
3.
Deeply seated nuclei in white matter:
Deeply seated nuclei in white matter:
from medial
to lateral:
•
Fastigial
Fastigial
nucleus
nucleus
.
•
Globose nucleus.
Globose nucleus.
•
Emboliform nucleus.
Emboliform nucleus.
•
Dentate
Dentate
nucleus:
nucleus:
largest
one.
CEREBELLAR
CEREBELLAR
CORTEX
CORTEX
Divided into
3 layers:
1.
Outer
Outer
molecular layer
molecular layer
2.
Intermediate
Intermediate
Purkinje cell
Purkinje cell
layer
layer
3.
Inner
Inner
granular
granular
layer
layer
1
2
3
1
2
3
CEREBELLAR MEDULLA
CEREBELLAR MEDULLA
AFFERENT FIBRES:
AFFERENT FIBRES:
Climbing fibres
Climbing fibres
:
:
from
inferior
inferior
olivary nucleus
olivary nucleus
, relay to
purkinje cells
Mossy fibres:
Mossy fibres:
rest of fibres:
1.
From
From
vestibular nuclei
vestibular nuclei
2.
From
From
spinal cord
spinal cord
3.
From
From
pons
pons
•
They
relay
to
granule
cells
which in turn
relay
to
purkinje
cells.
•
Finally
all afferent fibres
passing through the medulla
relay to
purkinje cells
in the
cortex.
CEREBELLAR MEDULLA
CEREBELLAR MEDULLA
Axons of Purkinje Cells
Axons of Purkinje Cells
are the only axons to
are the only axons to
leave the
leave the
cortex
cortex
to
to
medulla
medulla
:
1.
The great majority of
axons
do not leave
cerebellum &
end in
deep cerebellar nuclei,
specially
Dentate
nucleus.
2.
Some of axons
leave
cerebellum
as efferent
fibres.
D
e
n
d
a
t
o
-
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u
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o
-
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a
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a
m
i
c
CEREBELLAR MEDULLA
CEREBELLAR MEDULLA
EFFERENT FIBRES
EFFERENT FIBRES
:
:
Most efferent fibres are
axons of
deep
cerebellar nuclei.
Main Efferents
go to nuclei of brainstem&
thalamus
:
1.
Vestibular nuclei
Vestibular nuclei
(cerebello-vestibular tract).
(cerebello-vestibular tract).
2.
Red nucleus
Red nucleus
(Dendato-rubro-thalamic tract).
(Dendato-rubro-thalamic tract).
3.
Ventral lateral nucleus of
Ventral lateral nucleus of
thalamus
thalamus
(Dendato-
(Dendato-
thalamic tract).
thalamic tract).
FUNCTIONAL SUBDIVISIONS
FUNCTIONAL SUBDIVISIONS
OF
OF
THE CEREBELLUM
THE CEREBELLUM
ARCHICEREBELLUM
ARCHICEREBELLUM
•
Vestibular
Vestibular
Part of
Part of
cerebellum:
cerebellum:
Flocculo-nodular lobe
.
Green
=
Archi-cerebellum,
Blue
=
Paleo-cerebellum
.
Pink
=
Neo-cerebellum.
ARCHICEREBELLUM
ARCHICEREBELLUM
Nuclei Related:
Nuclei Related:
Fastigial
Fastigial
Afferents:
Afferents:
from
Vestibular
nuclei
(Vestibulocerebellar
fibres),
(through ICP)
Efferents cortical
Efferents cortical
(purkinje cell) Fibres
(purkinje cell) Fibres
project :
project :
to Fastigial
nucleus, which projects to
vestibular nuclei
(through
ICP) + to
Reticular
formation
Function:
Function:
controls body
Balance
(via vestibulospinal &
reticulospinal tracts).
Control of eye movement
(via VO Reflex)
PALEOCEREBELLUM
PALEOCEREBELLUM
•
Spinal
Spinal
Part of
Part of
cerebellum:
cerebellum:
Vermis & Paravermis
Green
=
Archi-cerebellum,
Blue
=
Paleo-cerebellum
.
Pink
=
Neo-cerebellum.
PALEOCEREBELLUM
PALEOCEREBELLUM
Nuclei Related:
Nuclei Related:
globose
&
emboliform
Afferents:
Afferents:
from
spinal cord
(dorsal & ventral
spinocerebellar tracts
through ICP & SCP,
respectively)
Efferents :
Efferents :
to
globose&embliform nuclei
which project to
red
nucleus
(through SCP)
Function:
Function:
controls
posture
& muscle tone
(via
Rubrospinal tract).
NEOCEREBELLUM
NEOCEREBELLUM
•
Cerebral
Cerebral
Part of
Part of
cerebellum:
cerebellum:
Rest of Cerebellum
.
NEOCEREBELLUM
NEOCEREBELLUM
Nuclei Related:
Nuclei Related:
Dentate
Afferents:
Afferents:
from
Pons
(Pontocerebellar fibres)
(through MCP)
Efferents:
Efferents:
to
Red nucleus
but mostly
but mostly
to
Ventral
Lateral Nucleus of
Thalamus
(through SCP)
then to
motor cortex
Function:
Function:
coordination
of
voluntary movements
(via descending
Corticospinal
&
corticobulbar tracts
or
R
ubrospinal tract
).
CEREBELLAR LESIONS
CEREBELLAR LESIONS
•
MIDLINE LESION:
MIDLINE LESION:
Loss of postural control.
•
UNILATERAL LESION:
UNILATERAL LESION:
“Cerebellar ataxia”
“Cerebellar ataxia”
causes
ipsilateral
ipsilateral
:
1.
Incoordination of
Incoordination of
arm
arm
:
:
intention tremors
intention tremors
(on
performing
voluntary movements
voluntary movements
)
2.
Incoordination of
Incoordination of
leg
leg
:
:
unsteady gait
3.
Incoordination of
Incoordination of
eye movements
eye movements
:
:
nystagmus
4.
Slowness of
Slowness of
speech
speech
:
:
dysarthria
(difficulty of speech).
THANK YOU
THANK YOU
SUMMARY
SUMMARY
Anatomically
Anatomically
,
the cerebellum is
divided into:
anterior, posterior & flocculonodular lobes.
Developmentally & functionally
Developmentally & functionally
,
it is
divided
into:
archi- paleo- & neocerebellum.
Archicerebellum (flocculonodular lobe)
Archicerebellum (flocculonodular lobe)
is the
oldest part of cerebellum, related to
fastigial
fastigial
nucleus, connected to
vestibular nuclei
vestibular nuclei
&
concerning for
control of body balance.
control of body balance.
SUMMARY
SUMMARY
Paleocerebellum (vermis & paravermis)
Paleocerebellum (vermis & paravermis)
is related
to
globose & emboliform
globose & emboliform
nuclei, connected to
spinal cord & red nucleus
spinal cord & red nucleus
& concerned with
regulation of
regulation of
posture & muscle tone.
posture & muscle tone.
Neocerebellum (most of human cerebellum)
Neocerebellum (most of human cerebellum)
is
related to
dentate
dentate
nucleus, connected to
pons
,
thalamus
. Its final destination is to
motor cortex
motor cortex
.
It is concerned with
coordination of voluntary
coordination of voluntary
movements.
movements.
Cerebellar lesions
lead to
ipsilateral
ipsilateral
incoordination (ataxia).
incoordination (ataxia).
QUESTION 1
QUESTION 1
Which
one
one
of the following nuclei is related
to neocerebellum?
1.
Fastigeal nucleus
2.
Dentate nucleus
3.
Globose nucleus
4.
Emboliform nucleus
QUESTION 2
QUESTION 2
To which part of the CNS the flocculonodular
lobe send its efferent fibers?
1.
Red nucleus
2.
Pons
3.
Vestibular nuclei
4.
Motor cortex
1.
The largest nucleus in the cerebellum can be seen by naked eye is :
a. Fastigial nucleus.
b. Globose nucleus.
c. Dentate nucleus.
d. Emboliform nucleus.
2. Which part in cerebellum is concerned with coordination of movement ?
a. Vermis.
b. Paravermis.
c. Folocculonodular lobe.
e. Neocerebellum.
3. Which nucleus contributes in the balance function of cerebellum ?
a. Dentate nucleus.
b. Fastigial nucleus.
d. Globose nucleuse.
e. Emboliform.
Explore the intricate details of the cerebellum with Prof. Ahmed Fathalla Ibrahim. Learn about the external features, anatomical subdivisions, internal structure, and nuclei of the cerebellum. Understand its origin, position in the brainstem, and connections to the brainstem. Gain insights into the effects of cerebellar lesions and the importance of its functional subdivisions. Delve into the layers of the cerebellar cortex and enhance your knowledge of this vital brain structure.
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Presentation Transcript
Prof. Ahmed Fathalla Ibrahim Prfessor of Anatomy
OBJECTIVES At the end of the lecture, students should: Describe the External features of the cerebellum (lobes, fissures). Describe briefly the Internal structure of the cerebellum. List the name of Cerebellar Nuclei. Relate the Anatomical to the Functional Subdivisions of the cerebellum. Describe the Important connections of each subdivision. Describe briefly the Main Effects in case of lesion of the cerebellum.
ORIGIN : ORIGIN : From Hindbrain. Position : Position : lies behind Pons & Medulla Separated from them by Fourth ventricle. CEREBELLUM
THE CEREBELLUM CONNECTION TO BRAIN STEM: by Inferior, Middle & Superior Cerebellar Peduncles.
EXTERNAL FEATURES It consists of two Cerebellar Hemispheres joined in midline by the Vermis. Its surface is highly convoluted forming Folia, separated by Fissures.
ANATOMICAL SUBDIVISION Primary Fissure Superior Surface Posterolateral = Secondary Fissure Anterroinferior Surface 1. 2. Anterior lobe: in front of primary fissure, on the superior surface. Posterior (middle) lobe: behind primary fissure (Between Primary & Secondary fissures = posterolateral). Flocculonodular lobe: in front of secondary (Posterolateral) fissure, on the inferior surface . 3.
ANATOMICAL SUBDIVISION http://accweb.itr.maryville.edu/myu/Bio321/..%5Cimage%5Ccerebellum.gif http://upload.wikimedia.org/wikipedia/commons/4/43/CerebellumDiv.png Secondary Fissur Or
CONSTITUENTS (Internal Structure and Nuclei of Cerebellum) 1. 2. 3. Outer grey matter: cerebellar cortex. Inner white matter: cerebellar medulla. Deeply seated nuclei in white matter: from medial to lateral: Fastigial nucleus. Globose nucleus. Emboliform nucleus. Dentate nucleus: largest one.
CEREBELLAR CORTEX Divided into 3 layers: 1. Outer molecular layer 2. Intermediate Purkinje cell layer 3. Inner granular layer 1 2 3 1 2 3
CEREBELLAR MEDULLA AFFERENT FIBRES: Climbing fibres: from inferior olivary nucleus, relay to purkinje cells Mossy fibres: rest of fibres: 1. From vestibular nuclei 2. From spinal cord 3. From pons They relay to granule cells which in turn relay to purkinje cells. Finally all afferent fibres passing through the medulla relay to purkinje cells in the cortex.
CEREBELLAR MEDULLA Axons of Purkinje Cells are the only axons to leave the cortex to medulla : The great majority of axons do not leave cerebellum & end in deep cerebellar nuclei, specially Dentate nucleus. Some of axons leave cerebellum as efferent fibres. 1. 2. Dendato-rubro-thalamic
CEREBELLAR MEDULLA EFFERENT FIBRES: Most efferent fibres are axons of deep cerebellar nuclei. Main Efferents go to nuclei of brainstem& thalamus : 1. Vestibular nuclei (cerebello-vestibular tract). 2. Red nucleus (Dendato-rubro-thalamic tract). 3. Ventral lateral nucleus of thalamus (Dendato- thalamic tract).
FUNCTIONAL SUBDIVISIONS OF THE CEREBELLUM
ARCHICEREBELLUM Vestibular Part of cerebellum: Flocculo-nodular lobe. Green = Archi-cerebellum, Blue= Paleo-cerebellum. Pink= Neo-cerebellum.
ARCHICEREBELLUM Nuclei Related: Fastigial Afferents: from Vestibular nuclei (Vestibulocerebellar fibres),(through ICP) Efferents cortical (purkinje cell) Fibres project : to Fastigial nucleus, which projects to vestibular nuclei (through ICP) + to Reticular formation Function: controls body Balance (via vestibulospinal & reticulospinal tracts). Control of eye movement (via VO Reflex)
PALEOCEREBELLUM Spinal Part of cerebellum: Vermis & Paravermis Green = Archi-cerebellum, Blue= Paleo-cerebellum. Pink= Neo-cerebellum.
PALEOCEREBELLUM Nuclei Related: globose & emboliform Afferents: from spinal cord (dorsal & ventral spinocerebellar tracts through ICP & SCP, respectively) Efferents : to globose&embliform nuclei which project to red nucleus (through SCP) Function: controls posture & muscle tone (via Rubrospinal tract).
NEOCEREBELLUM Cerebral Part of cerebellum: Rest of Cerebellum.
NEOCEREBELLUM Diagram depicts the outflow pathways from the cerebellar cortex to the cerebral cortex and red nucleus. The linkage between the cerebellum and cerebral cortex involves a disynaptic pathway an initial projection from the dentate nucleus to the ventrolateral thalamic nucleus and a second projection from the thalamus to the motor and premotor cortices (both shown in red). The pathway from the cerebellum to the red nucleus involves a projection from the interposed nuclei to the red nucleus (shown in green). Both of these outputs from the cerebellum to the contralateral thala-mus and red nucleus are mediated through the superior cerebellar peduncle. The corticospinal and rubrospinal pathways are indicated in blue. Nuclei Related: Dentate Afferents: from Pons (Pontocerebellar fibres) (through MCP) Efferents: to Red nucleus but mostly to Ventral Lateral Nucleus of Thalamus (through SCP) then to motor cortex Function: coordination of voluntary movements (via descending Corticospinal & corticobulbar tracts or Rubrospinal tract).
CEREBELLAR LESIONS MIDLINE LESION: Loss of postural control. UNILATERAL LESION: Cerebellar ataxia causes ipsilateral : 1. Incoordination of arm: intention tremors (on performing voluntary movements) 2. Incoordination of leg: unsteady gait 3. Incoordination of eye movements: nystagmus 4. Slowness of speech: dysarthria (difficulty of speech).
THANK YOU THANK YOU
SUMMARY Anatomically, the cerebellum is divided into: anterior, posterior & flocculonodular lobes. Developmentally & functionally, it is divided into: archi- paleo- & neocerebellum. Archicerebellum (flocculonodular lobe) is the oldest part of cerebellum, related to fastigial nucleus, connected to vestibular nuclei & concerning for control of body balance.
SUMMARY Paleocerebellum (vermis & paravermis) is related to globose & emboliform nuclei, connected to spinal cord & red nucleus & concerned with regulation of posture & muscle tone. Neocerebellum (most of human cerebellum) is related to dentate nucleus, connected to pons, thalamus. Its final destination is to motor cortex. It is concerned with coordination of voluntary movements. Cerebellar lesions lead to ipsilateral incoordination (ataxia).
QUESTION 1 Which one of the following nuclei is related to neocerebellum? 1. Fastigeal nucleus 2. Dentate nucleus 3. Globose nucleus 4. Emboliform nucleus
QUESTION 2 To which part of the CNS the flocculonodular lobe send its efferent fibers? 1. Red nucleus 2. Pons 3. Vestibular nuclei 4. Motor cortex
1. The largest nucleus in the cerebellum can be seen by naked eye is : a. Fastigial nucleus. b. Globose nucleus. c. Dentate nucleus. d. Emboliform nucleus. 2. Which part in cerebellum is concerned with coordination of movement ? a. Vermis. b. Paravermis. c. Folocculonodular lobe. e. Neocerebellum. 3. Which nucleus contributes in the balance function of cerebellum ? a. Dentate nucleus. b. Fastigial nucleus. d. Globose nucleuse. e. Emboliform.
