Gross Anatomy and Functional Localization
Done by
Dr.Rafid Remthan Al-Temimi
Clinical Radiology
CAMB,DMRD,M.B.Ch.B.,.
المرحلة
:
الثانية
المادة
:
التشريح
ج
امعة ذي قار
/
كلية الطب
الدكتور
رافد رمثان التميمي
ANATOMY
The anatomical structures of the limbic system consists of an interconnected complex of basal brain elements.
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Dr.Rafid Remthan AL-Temimi,Clinical Radiology,CAMB, 2020
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Limbic system
It is formed of groups of nuclei connected together by fiber
bundles.
Nuclei of the limbic system
:
1.
Limbic lobe
: formed of the
cingulated
gyrus,
parahippocampal
gyrus and the
uncus
.
2.
Hippocampus
: is continuous externally with the parahippocampal
gyrus.
3.
Hypothalamus
: especially the mamillary bodies.
4.
Thalamic nuclei
: anterior and medial nuclei.
5. The
prefrontal cortex
(the personality center).
6.
Amygdaloid nucleus
.
7.
Septal area
(medial olfactory area): below the rostrum.
8.
Habenular nucleus
.
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Dr.Rafid Remthan AL-Temimi,Clinical Radiology,CAMB, 2020
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Anatomy lecture . 2
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Dr.Rafid Remthan AL-Temimi,Clinical Radiology,CAMB, 2020
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Fiber bundles of limbic system
1.
Fornix
: it arises from the hippocampus and terminates in the mamillary body.
The fornix is formed of 4 parts:
a.
Fimbria
:
is the continuation of alveus which is formed of axons of the
neurons of the hippocampus and passes along its medial border.
b.
Crus
of the fornix: is the continuation of the fimbria below the
splenium.
c.
Body
of the fornix: the two crura fuse to form the body of the fornix.
d.
Anterior column
of the fornix: each one terminates in the
mamillary body.
2.
Cingulum
: is the fiber bundle of the limbic lobe.
3.
Mamillothalamic tract
: connects the mamillary body with the anterior
thalamic nucleus.
4.
Stria terminalis
: it begins in the septal area and in the habenular nucleus.
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Dr.Rafid Remthan AL-Temimi,Clinical Radiology,CAMB, 2020
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College Of medicine
Anatomy lecture . 2
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Dr.Rafid Remthan AL-Temimi,Clinical Radiology,CAMB, 2020
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Limbic system
• Limbic mean border !!
• Border between the cortex and the
thalamus ..
• Involved in
emotion, behavour,
drive and memory.
• Limbic lobe is a primitive lobe
composed mainly from cingulate
gyrus (1) parahippocampal gyrus
(2) and uncus (3) ) ..
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3
3
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Limbic system
1.
Limbic lobe
2.
Orbitofrontal cortex :-
a region in the frontal
lobe involved in the process of decision-
making.
3.
Piriform cortex :-
part of the olfactory system.
4.
Entorhinal cortex :-
related with memory
and associative components
5.
Hippocampus and associated structures :-
which
play a central role in the consolidation of new
memories.
6.
Fornix :-
a white matter structure connecting
the hippocampus with other brain structures,
particularly the mammillary bodies and septal
nuclei
• The following structures are, or have
been considered, part of the limbic
system:
Cortical areas:
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Limbic system
1. Septal nuclei :-
a set of structures that lie in
front of the lamina terminalis, considered a
pleasure zone.
2. Amygdala :-
located deep within the
temporal lobes and related
with a number of emotional
processes.
3. Nucleus accumbens :-
involved in reward,
pleasure, and addiction.
1
2
2
Subcortical areas:
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Nucleus accumbens ( arrow )
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Limbic system
1. Hypothalamus :-
a center for the limbic system,
connected with the frontal lobes, septal nuclei
and the brain stem reticular formation via the
medial forebrain bundle,with the hippocampus
via the fornix, and with the thalamus via
the mammillothalamic fasciculus.It
regulates a great number of autnomic
processes
2.
Mammillary bodies
:- part of the hypothalamus
that receives signals from the hippocampus via
the fornix and projects them to the thalamus.
3.
Anterior nuclei of thalamus :-
receive input
from the mammillary bodies. Involved in
memory processing.
1
2
Diencephalic structures
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Limbic system
Grey mater
1. the subcallosal gyri
2. the cingulate gyri
3. and the parahippocampal gyri
4. hippocampal formation
5. the amygdaloid nucleus
6. the mammillary bodies
7. the anterior thalamic nucleus
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2
1
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Hippocampal
formation
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Limbic system
White mater
1. The alveus :- borders the wall of the
lateral ventricle
2. The fimbria : along the medial
Edge of hippocampus
( BECOME THE ALVEUS !! )
3. the fornix
4. the mammillothalamic tract,
5. the stria termrinnalis :- along the
lateral ventricular border of thalamus )
constitute the connecting pathways of
this system.
1
2
3
4
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Hippocampal formation
• Forms the :-
• 1- hippocampus
• 2- dentate gyri
• 3- Parahippocampual gyri
• The hippocampus extends
throughout the entire length of the
floor of the inferior horn of the lateral
ventricle the temporal lobe
• Its anterior end is expanded (pes
hippocampus)
• Involved in conversion of short to long
term memory
1
2
3
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Dentate gyrus
• A narrow, notched band of gray
matter between the fimbria &
parahippocampal gyrus
• Anteriorly
the
DG
becomes
continuous with the uncus &
Posteriorly
with
the
indusium
griseum
• Indusium griseum :-
is a thin layer of
gray matter that covers the corpus
callosum
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Amygdaloidal body
• In temporal lobe and closely related
to uncus !
• Influence the body response
to environmental changes.
• Amygdala function :-
• Memory
• Decision maker
• Emotional reaction
Response
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Amygdaloidal body
• In temporal lobe and closely related
to uncus !
• Influence the body response
to environmental changes.
• Amygdala function :-
• Memory
• Decision maker
• Emotional reaction
Response
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Dr.Rafid Remthan AL-Temimi,Clinical Radiology,CAMB, 2020
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Gender different to amygdala
• Amygdala is larger in males
• Right amygdala is related to taking action and
respond physically ?
• Right amygdala is more active in men
• Left amygdala is related to
active in
emotional response ?
• Left amygdala is more
women
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Dr.Rafid Remthan AL-Temimi,Clinical Radiology,CAMB, 2020
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White mater of limbic system
Alveus (1)
Fimbria (2)
Crus of
fornix (3)
Fornix (4)
Cover the
hippocampus
3
4
1
2
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Fornix
• Arch-shaped lamella of white substance hanged to corpus callosum by
septum pellucidum !!
• Posterior crura unite in the midline to form the body
• The body diverges anterior as the two columns which end in the
mamillary bodyA commissure is present between the two crura to
connect both hippocampi .
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it arises from the hippocampus and terminates in the mamillary
body. The fornix is formed of 4 parts:
a.
Fimbria
: is the continuation of alveus which is formed of
axons of the neurons of the hippocampus and passes along its
medial border.
b.
Crus
of the fornix: is the continuation of the
fimbria below the splenium.
c.
Body
of the fornix: the two crura fuse to form the body of
the fornix.
d.
Anterior column
of the fornix: each one
terminates in the mamillary body.
Connections
Afferent connections
:
1. Fibers arise from the cingulated gyrus pass to the
hippocampus
.
2. Fibers from hippocampus of one side pass to
hippocampus
of the other side along the fornix.
3. Fibers arise from the parahippocampal and dentate gyri pass to
hippocampus
.
4. Fibers arise from the olfactory association cortex pass to the
hippocampus
.
Efferent connections
:
The fibers of the fornix are distributed to:
1. Fibers pass to the anterior commissure to the
mamillary body
and
anterior part of ypothalamus
.
2. Fibers pass to the anterior commissure to end in the
anterior nuclei of thalamus
.
3. Fibers pass to the anterior commissure to enter the
tegmentum of the midbrain
.
4. Fibers join the
habenular nuclei
.
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Functions of limbic system
• 1- emotional behavior
The limbic system,
via the hypothalamus and
its connections with the outflow of the
autonomic nervous system and its control of the
endocrine system, is
able to influence many
aspects of emotional behavior.
• These include particularly the reactions of fear
and anger and the emotions associated with
sexual behavior.
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Dr.Rafid Remthan AL-Temimi,Clinical Radiology,CAMB, 2020
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Functions of limbic system
• 2- Memory
• There is also evidence that the
hippocampus is concerned with
converting recent memory to long-term
memory. A lesion of the hippocampus
results in the individual being unable to
store long-term memory.Memory of
remote past events before the lesion
developed is unaffected
• This condition is called
anterograde amnesia.
• It is interesting to note that injury to the
amygdaloid nucleus and the hippocampus
produces a greater memory loss than
injury to either one of these structures
alone.
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Dr.Rafid Remthan AL-Temimi,Clinical Radiology,CAMB, 2020
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Functions of limbic system
• 3- response to environment
• various afferent and efferent
connections of the limbic system
provide
integration
pathways
for
the and
effective
homeostatic responses to a wide
variety of environmental stimuli.
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Dr.Rafid Remthan AL-Temimi,Clinical Radiology,CAMB, 2020
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Functions of limbic system
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Dr.Rafid Remthan AL-Temimi,Clinical Radiology,CAMB, 2020
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Part
Function
Amygdala
AGGRESSION and FEAR
Cingulate gyrus
AUTONOMIC FUNCTION
Hippocampus
RECENT MEMORY
Hypothalamus
ENDOCRINE FUNCTION
Mammillary body
LONG MEMORY
Nucleus accumbens
ADDICTION
Prefrontal area
PERSONALITY
Parahippocampus
SPATIAL MEMORY
Malfunction of the limbic system
The malfunction is involved in psychiatric disorder, including
schizophrenia
,
depression
,
and
senile dementia
. Antipsychotic drugs block limbic dopamine receptors.
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Dr.Rafid Remthan AL-Temimi,Clinical Radiology,CAMB, 2020
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Lesions
1. Lesion in the hippocampus causes loss of the recent memory.
2.In
Alzheimer's disease
, there is extensive degeneration in the hippocampus.
3.Lesions in the amygdaloid nucleus cause
loss of the aggressive behavior, fear and
anger
.
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Thank you……