The document discusses the limbic system and reticular formation. It describes the limbic system as a collection of brain structures involved in emotion, memory, and olfaction. The key components are the limbic lobes, hippocampus, amygdala, and septal area. The hippocampus is important for forming new memories. The amygdala is involved in emotions like fear and aggression. Lesions can cause disorders like Korsakoff's psychosis, temporal lobe epilepsy, and Alzheimer's disease. The reticular formation is involved in consciousness, and lesions can lead to conditions like coma, Parkinson's disease, and schizophrenia.

1. KAMPALA INTERNATIONAL UNIVERSITY-
WC
DEPARTMENT OF SURGERY
ADVANCED ANATOMY II
LIMBIC SYSTEM AND RETICULAR FORMATION
Lecturer:- Dr Abdifatah Abdi Ali
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2. outline
Introduction
Components
Functions
Lesions associate with disorders
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3. INTRODUCTION
Limbic system was a term loosely
used to describe the part of the
brain between the cerebral
cortex and the hypothalamus, a
little understood area of the
brain.
Today, it is
known to play a vital role in
emotion, behavior, memory and
olfaction.
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4. INTRODUCTION
 The term "limbic" is from the
Latin word Limbus, for
"border" or "edge“, it is also
means ring.
 It separates the medial
surface of the cerebral cortex
from the diencephalon
 It consists of a number of
cortical & subcortical
structures with looped
connections that all project to
the hypothalamus
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5. COMPONENTS
The limbic system is composed of:
Nuclei
Fiber bundles
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6. COMPONENTS: Nuclei
1. Limbic lobes: 3 parts:
Cingulate gyrus, Para-hippocampal
gyrus, Uncus
2. Hyppocampal formation:
hippocampus, Dentate gyrus
3. Mamillary body: Hypothalamus
4. Thalamus: Anterior nucleus,
Medial nucleus
5. Prefrontal cortex
6. Amygdaloid nucleus
7. Septal area
8. Habenular nucleus
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7. COMPONENTS: Nuclei
1. Limbic lobes: 3 parts:
Cingulate gyrus, Para-hippocampal
gyrus, Uncus
2. Hyppocampal formation:
hippocampus, Dentate gyrus
3. Mamillary body: Hypothalamus
4. Thalamus: Anterior nucleus, Medial
nucleus
5. Prefrontal cortex
6. Amygdaloid nucleus
7. Septal area
8. Habenular nucleus
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8. COMPONENTS: Nuclei
1. Limbic lobes: 3 parts:
Cingulate gyrus, Para-hippocampal
gyrus, Uncus
2. Hyppocampal formation:
hippocampus, Dentate gyrus
3. Mamillary body: Hypothalamus
4. Thalamus: Anterior nucleus, Medial
nucleus
5. Prefrontal cortex
6. Amygdaloid nucleus
7. Septal area
8. Habenular nucleus
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9. COMPONENTS: Nuclei
1. Limbic lobes: 3 parts:
Cingulate gyrus, Para-
hippocampal gyrus, Uncus
2. Hyppocampal formation:
hippocampus, Dentate gyrus
3. Mamillary body:
Hypothalamus
4. Thalamus: Anterior nucleus,
Medial nucleus
5. Prefrontal cortex
6. Amygdaloid nucleus
7. Septal area
8. Habenular nucleus
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10. COMPONENTS: Fiber bundles
Connection between
Nucleis
Fiber bundle
Limbic lobe Cingulum
Hippocampus/Mamillary body Fornix
Mamillary body/Anterior thalamic
nucleus
Mamillothalamic tract
Medial thalamic nucleus/Prefrontal cortex Antero thalamic radiation
Amygdaloid nucleus/septal area Stria terminalis
Septal area/habernular nucleus Stria medullaris thalami
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12. LIMBIC SYSTEM
 components structures: limbic
cortex(lobes), amygdala, Hippocampus
and septal area.
The structures form connections
between the limbic system and the
hypothalamus, thalamus and cerebral
cortex
The hippocampus ( in memory and
learning), the limbic system( in the
control of the emotional responses).
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13. LIMBIC SYSTEM
Cortical structures: Limbic lobe,
Hippocampal formation, Septal
areas(fornix connecting the
hippocampus with mammillary bodies
and septal nuclei and prefrontal
area(olfactory cortex)
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14. LIMBIC SYSTEM
Limbic lobe:
C-shaped ring of Grey matter on
the medial side of each cerebral
hemisphere, surrounding the
corpus callosum.
It includes: subcollosal area,
cingulate gyrus, isthmus,
parahippocampal, uncus
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15. LIMBIC SYSTEM
Hippocampus: it is a limbic
system structure that involved in
FOS( formation organization and
storage of memories), important
in forming new memories and
connecting, emotions and senses
such as smell and sound , to
memories paired structures in
each cerebral hemisphere.
It is as a memory indexer by
sending memories to the
appropriate part of the cerebral
hemisphere for long-term storage
and retrieving them when
necessary
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16. LIMBIC SYSTEM
Hippocampus:
Site: scrolled ( infolding) structure
in the inferomedial part of the
temporal lobe
Fonction: memory(file new
memories as they occur)
The hippocampus connection are
necessary for consolidation of new
short term memoies
Its principal efferent pathway is
called the fornix(=it is C-shaped
group of fibers connecting the
hippocampus with mammillary
body, then to the anterior nuclei of
thalamus
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17. LIMBIC SYSTEM
Hippocampus(fornix):
Fornix is consist of 2 fimbria, 2
crus, 1 body and 2 column.
 the fornix is an important
component of PAPEZ
CIRCUIT(based on connecting
connecting the hypothalamus with
limbic lobe to control emotion
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18. LIMBIC SYSTEM
amygdale:
Site: almost shaped mass of nuclei that lies
near( deep within) the temporal pole, close
to the tail of the caudate nucleus.
Function, the amygdale is involved in
emotion, fear, anger, aggression, hormonal
secretion.
Connection of amygdale:
Inputs(association areas of visual, auditory
and somatosensory cortices),
Outputs(hypothalamus, autonomic nuclei in
the brain stem
Lesion of the amygdale : lack of emotional
responses and docility
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19. Functions of limbic system
It control a variety of functions including:
 Emotions,
 Emotional responses
 Behavior & Mood (happy, cry, laugh, sad, afraid, aggression,
depression)
 Motivation.
 Memory.
 Visceral & Motor responses involved in (sex, pleasure, hunger,
and reproduction).
 Olfaction.
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20. Lesions associated with limbic lobe disorders
 Korsakoff’s psychosis (Retrograde = loss of new memories at the
time of lesion with retained old memories & anterograde amnesia=
inability to gain new memories)
 Temporal lobe epilepsy
 The hippocampus is a common focus site in epilepsy, and can be
damaged through chronic seizures.
 It is sometimes damaged in diseases such as herpes encephalitis,
 Alzheimer’s disease: The hippocampus is one of the first brain areas to
show damage in Alzheimer's disease
 Schizophrenia.
 Lesion in the Amygdaloidal nucleus causes loss of aggressive
behavior, fear and anger
 Bilateral lesion of the amygdaloidal and hippocampus causes
increased appetite and abnormal hypersexual behavior
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22. Lesions associate with reticular
formation
Lesions to major pathways of the reticular activating system can thus
impair consciousness and severe damage can cause:
 coma or a persistent vegetative state,
 Parkinson’s disease
 Schizophrenia
 Secondary brain injury
 Diffuse axona injury(DAI)
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23. REFERENCES
1. SNELL RS. Clinical Neuro-anatomy. 7th ed.
2. BRS Neuro-anatomy
3. Textbook of Anatomy : Head, Neck and Brain.
(Vishram Sing)(z-lib.org)
1. Netter’s Atlas of Human Anatomy 6th edition
2. Teach me anatomy.
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