Human Brain
• Brain: about 1400 g (2% of body weight) but receives
20% of body blood supply.
1. Cerebral hemispheres
2. Basal Ganglia
3.Diencephalon: thalamus & hypothalamus.
Brain Stem:
1. Midbrain
2. Pons
3. Medulla
The Brain
• Largest organ in the body at almost 3 lb (1400 g).
• Brain functions in sensations, memory, emotions, decision
making, behavior
Embryonic and Fetal Development of the Human
Brain
Actual Size
Actual Size
Developmental Anatomy of the NS
• Begins in 3rd week
– ectoderm forms thickening (neural plate)
– plate folds inward to form neural groove
– edges of folds join to form neural tube
• Neural crest tissue forms:
– spinal & cranial nerves
– dorsal root & cranial nerve ganglia
– adrenal gland medulla
• Layers of neural tube form:
– marginal layer which forms white matter
– mantle layer forms gray matter
– ependymal layer forms linings of cavities
within NS
Brain growth
• Changes in brain growth clearly show the
emphasis on “head” development early on.
• The brain is 25% of it’s adult weight at birth, but
body weight is only 5% of adult weight.
• These physical indicators illustrate the
cephalocaudal directionality of development, but
this directionality is more general.
• Motor skills tend to develop in this order (children
can sit before they can stand).
Principal Parts of the Brain
• Cerebrum
• Diencephalon
– thalamus &
hypothalamus
• Cerebellum
• Brainstem
– medulla, pons &
midbrain
Protective Coverings of the Brain
• Bone, meninges &
fluid
• Meninges same as
around the spinal cord
– dura mater
– arachnoid mater
– pia mater
• Dura mater extensions
– falx cerebri
– tentorium cerebelli
– falx cerebelli
Cerebrum
(Cerebral Hemispheres)
• Cerebral cortex is gray matter
overlying white matter
– 2-4 mm thick containing billions
of cells
– grew so quickly formed folds
(gyri) and grooves (sulci or fissures)
• Longitudinal fissure separates left
& right cerebral hemispheres
• Corpus callosum is band of white
matter connecting left and right
cerebral hemispheres
• Each hemisphere is subdivided into 4
lobes
Cerebral White Matter
• Association fibers between gyri in same hemisphere
• Commissural fibers from one hemisphere to other
• Projection fibers form descending & ascending tracts
CEREBRAL HEMISPHERES
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Poles, Borders, Surfaces and Lobes
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Each cerebral hemisphere has 3 poles, 3borders, 3 surfaces, 4 major sulci and 4 lobes
The 3 poles are:
1- Frontal pole: is the anterior end
2- Occipital pole: Posterior end
3- Temporal pole: the anterior end of the temporal lobe
 the 3 borders:
1- Superior border that related to a venous sinus named superior sagittal sinus.
2- Inferomedial border that divided into:
• Medial orbital border: from the frontal pole to optic chiasma
• Hippocampal border: around midbrain
•Medial Occipital border: from splenium of corpus callosum to the occipital pole
3- inferolateral boder
 The 3 surfaces:
1- Lateral surface: convex and related to the vault of the skull
2- Medial surface: is flat and separated from the opposite one by falx cerebri
3- Inferior surface: is divided by the lateral sulcus into:
•Orbital part: lies on the roof of the orbit
• Tentorial part: lies on the tentorium cerebelli
 The 4 major sulci:
1- Central sulcus
2- Lateral sulcus: begins on the inferior surface and consists of stem and 3 rami: anterior
ramus, ascending ramus and posterior ramus.
3- Calcarine sulcus: begins below splenium of corpus callosum and arches
upwards and backwards to reach the occipital pole
4- Parieto-occipital sulcus: it extends from the middle of calcarine sukcus to
the superior border and continues on the lateral surface
Lobes and Fissures
• Longitudinal fissure (green):
Between the 2 cerebral
hemispheres
• Central sulcus (yellow)
– Between precentral &
postcentral gyrus
•
•
•
•
•
•
•
Parieto-occipital sulcus
Lateral sulcus (blue)
Calcarine sulcus:
Frontal lobe
Parietal lobe
Occipital lobe
Temporal lobe
Central sulcus
Parieto-occipital
Ascending ramus of
lateral sulcus
calcarine
Anterior ramus of lateral
sulcus
Posterior ramus of
lateral sulcus
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18
Superior
border
Medial
orbital
Hippocampal
border
Medial
occipital
Occipital pole
Frontal pole
Temporal pole
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Sulci, Gyri and Cortical Areas of
Superolateral Cerebral Surface
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Main cortical areas of the lateral surface:
 primary motor area ( area 4):
• site: precentral gyrus, anterior wall of central sulcus
• function: give origin of 40% of corticospinal tract ( pyramidal tract) that
intiate the highly skilled movement such as playing piano
• it controls the opposite side of the body and the body represented in this area
upside down
 premotor area (area 6):
• site: anterior to the motor area
•Function: Gross movement, execution of learned motor activity by storing
programs of motor activity learned by experience such as walking, dancing,…..
 Motor speech area ( Broca’s area, area 44&45)
• site: posterior part of the inferior frontal gyrus of the dominant hemisphere
(opercular and trianglar gyri)
• function: coordinates actions of the muscles used in speech ( lips, tongue and
larynx)
 Prefrontal cortex ( personlaity center) ( areas 9.10,11&12)
• site: frontal pole ( anterior to the premotor area)
• function: make up personality, intellectual functions and his reactions to
situations
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General somatosensory area (area 3,2,1):
•Site: postcentral gyrus and posterior wall of the central sulcus
• function: it recieves all sensations from the opposite side of body and face
 Somatosensory association areas ( area 5,7 & 40):
• site: 1- area 5, 7 : in the superior parietal lobule
2- area 40: in supramarginal gyrus
• function: Stereognosis. Interpretation of senses percieved in the general sensory area
 Primary auditory area ( area41&42):
• site: in the middle of the upper surface of the superior temporal gyrus ( floor of the lateral
sulcus)
• function: receives the sounds from both ears especially the opposite one
 Auditory association area ( area22):
• site: in the dominant hemisphere in the posterior part of the superior temporal gyrus
• function: recognition of sounds. It is a sensory speech area ( we learn by hearing)
 Primary visual area ( area17):
• site: lips of calcarine sulcus ( above and below it)
•Function: perception of the light
 Visual association area areas 18, 19 & 39)
• site: 1- Areas (18,19) : Around ( above and below) the primary visual area
2- Area (39): Angular gyrus
• function: recognize of what we see, color vision
•Angular gyrus: comprehension of written language
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Sensory Areas of Cerebral Cortex
Receive sensory information from the thalamus
Primary somatosensory area = postcentral gyrus = 1,2,3
Primary visual area = 17 (vision)
Primary auditory area = 41 & 42 (sound)
Primary gustatory area = 43 (taste)
Motor Areas of Cerebral Cortex
• Voluntary motor initiation
– Primary motor area = 4 = precentral gyrus
• controls voluntary contractions of skeletal muscles on other side
– Motor speech area = 44,45 = Broca’s area
• production of speech -- control of tongue & airway
Association Areas of Cerebral Cortex
•
•
•
•
•
•
•
Somatosensory area = 5 & 7 (integrate & interpret)
Visual association area = 18 & 19 (recognize & evaluate)
Auditory association area = 22 (Music & speech and nois)
Gnostic area = 5,7= integrates sensory interpretation from the association areas to
form common thought
Wernike’s area 39 & 40 (integrate all senses & speech to words)
Premotor area = 6 (learned skilled movements such as typing, piano player, gymnastic)
Frontal eye field =8 (scanning eye movements such as phone book)
Insula within Lateral Fissure
Sulci, Gyri and Cortical Areas of
Medial Cerebral Surface
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Central sulcus
Paracentral lobule
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Main cortical areas of the medial surface:
 primary motor area ( area 4):
• site: anterior part of the paracentral area ( leg and foot area)
General somatosensory area (area 3,2,1):
•Site: posterior part of the paracentral lobule (leg and foot area)
Main cortical areas of the inferir surface:
 primary olfactory area
• site: uncus
Olfactory association area (area 28):
•Site: anterior part of parahippocampal gyrus
• function: discrimination of different odors
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Sulci, Gyri and Cortical Areas of
Inferior Cerebral Surface
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28
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Reticular Formation
• Scattered nuclei in medulla, pons & midbrain
• Reticular activating system (RAS)
– alerts cerebral cortex to sensory signals (sound of
alarm, flash light, smoke or intruder) to awaken
from sleep
– maintains consciousness & helps keep you awake
with stimuli from ears, eyes, skin and muscles
• Motor function is involvement with
maintaining muscle tone (postural muscles)
Cerebellum
•
•
Is the largest part of hindbrain
2 cerebellar hemispheres and vermis (central area) An organ concerned with the coordination of the
voluntary movements
Situation
• Below the posterior portion of cerebrum ( separated from it by tentorium cerebelli)
• In the posterior cranial fossa
•
Function
–
–
correct voluntary muscle contraction and posture based on sensory data from body about actual movements
sense of equilibrium
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Cerebellum
Structure and Function
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Structure
• Ovoid in shape
• Two hemispheres
• Seaparated by vermis a median strip of tissue
• Grey matter forms the cerebellar cortex
• White matter in depth
• 4 deep cerebellar nuclei (from medial to lateral)
1. Fastigial N 2. Globose N. 3. Emboliform N.
4. Dentate N.
• Cerebellum communicates with other regions of the CNS
through three large nerve tracts called the cerebellar peduncles
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Cerebellum
• Cerebellar cortex (folia) & central nuclei are grey matter
• Arbor vitae = tree of life = white matter
Intracerebellar Nuclei
All are present beneath •
the roof of the 4th
ventricle:
These are: •
1- Fastigial N. •
2- Globose N. •
3- Emboliform N. •
4- Dentate N. •
Important fissures of cerebellum:
1. Horizontal fissure: divides the cerbellum into superior and inferior sufaces
2. Primary fissure: at the junction of its anterior1/3 and posterior 2/3
3- posterolateralfissure: extending on the inferior surface separating the
flocculonodular lobe from the rest of the of cerebellar hemisphere
Subdivisions of cerebellum
 Anatomically divided into:
1. Anterior lobe: anterior to primary fissure
2. Posterior lobe: between primary and horizontal fissures
3. Flocculonodular lobe: lies caudal to the posterolateral fissure
 Functionally the cerbellum divided into 3 functional zones
1. Archicerebellum (Vestibloceremellum): consists of flocculonodular lobe
2. Paleoceremellum (Spinocerebellum): consists of vermal and paravermal
zones of the anterior and posterior lobes
3. Neocerebellum ( Cerebrocerebellum): consists of lateral zone of the cerebellar
hemisphere
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PARTS
CONTROL
flocculonodular
Balance and
maintenance of muscle
tone
Motor coordination and
muscle tone
Paleocerebellum
Neocerebellum
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Planning and automatic
control of movement
Sensory input for cerebellum
Derived from
1. Muscles and joints
2. Eyes
3. Ears (from semicircular canals)
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• FUNCTIONS:
• Each cerebellar hemisphere controls the same side of the body.
• Cerebellar activities are carried out below the level of
consciousness i.e. not under voluntary control.
• Its function is entirely motor.
• 1-Motor learning & retention
• 2-Planning and fine tuning of skeletal muscle contraction
• 3-Co-ordination of voluntary motor activity (force,
extent, speed and duration) so that movements are smooth,
even and precise
• 4-Control of muscle tone
• 5-Control of equilibrium and maintenance of posture
Applied anatomy
Cerebellar dysfunction cause:
1- Intension tremors: tremors absent at rest and appears when the patient
start to move
2- Disturbance in muscle coordination:
a. Ataxia: the patient walks with wide legs far apart to avoid falling
b. Nystagmus: due to incoordination of the extraoccular
c. Scanning speech: slurred and hesitating with pauses in the wrong place
3- Disturbance in the range of movement (dysmetria with overshooting)
4- Disturbance in proper initiation and termination of movement
(dysdiadochokinesia)
• CHARCOT’S TRIAD: A combination of nystagmus, dysarthria and intention
tremor, is highly diagnostic of the Cerebellar disease
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CEREBELLAR DYSFUNCTIONS
• Note:
• The Cerebellar disease affects the muscular activity on the same side of
the body
• No sensory deficits
• No paralysis or atrophy of muscles
• A midline lesion ( archicerebellum ) as tumor
leads to loss of postural control.
• A unilateral hemisphere lesion (neocerebellum)
causes ipsilateral in-coordination of the arm
(intention tremors), and of the leg leads to
unsteady gait.
• Bilateral dysfunction caused by alcoholic
intoxication, hypothyroidism, or inherited
cerebellar degeneration causing slowness, &
slurring of speech (dysarthia), in-coordination of
both arms, and staggering, wide-based &
unsteady gait (cerebellar ataxia).
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Lesion of anterior lobe, Ataxia,
Clumsy movement of the lower
limb.
Floculonodular lobe syndrom:
truncal ataxia standing on wide
base & reeling from side to side.
Posterior Lobe •
Syndrome
Intention tremors •
Cerebellar Peduncles
Inferior Cerebellar peduncle: (Restiform body) •
It connects the cerebellum with the medulla. •
It arises from superior half of medulla. •
It contains many afferent fibers & few efferent •
fibers.
• Example of:
• Afferent:
Efferent
• Vestibulocerebellar tract.
• Olivocerebellar tract.
• Reticulocerebellar tract.
Dorsal spinocerebellar tract.
Cerebello-vestibular from fastigial
Cerebello-reticular from fastigial.
Middle Cerebellar Peduncle: Brachium Pontis
• It connects the cerebellum with the pons.
• It is the thickest of the 3 peduncles.
• It contains mainly afferent fibers which form a part of the CorticoPonto-Cerebellar pathway.
• Afferent:
• 1- Ponto-Cerebellar fibers: arise from pontine nuclei and cross the
middle line to the opposite side and terminate in the cerebellar
hemisphere of the opposite side.
Superior cerebellar peduncle: Brachium conjunctivum.
• It connects the cerebellum with the midbrain.
• It contains mainly efferent fibers, but it contain some
afferent fibers.
• Afferent:
• 1- Ventral Spinocerebellar tract.
• 2- Tectocerebellar tract.
• 3- Trigeminocerebellar
• Efferent:
• 1- Dentatorubral tract.
• 2- Dentatothalamic tract. It reaches the ventrolateral nucleus
of thalamus either directly or after relay in red nucleus. Through this
the cerebellum can coordinate activity of cerebral cortex.
Cerebellar Peduncles
• Superior, middle & inferior peduncles attach to brainstem
– inferior carries sensory information from spinal cord
– middle carries sensory fibers from cerebral cortex & basal ganglia
– superior carries motor fibers that extend to motor control areas
• 3 arteries: one to
superior surface & 2 to
inferior surface.
• (PICA) posterior Inferior
Cerebellar artery: from
vertebral
• (AICA) anterior Inferior
Cerebellar artery: from
basilar.
• Superior Cerebellar
artery, from basilar.
Blood Supply
Diencephalon Surrounds 3rd Ventricle
• Surrounds 3rd ventricle
•
•
•
•
Superior part of walls is thalamus
Inferior part of walls & floor is hypothalamus
Diencephalon is formed of 4 parts:
1- Thalamus 2- Hypothalamus 3- Epithalamus
4- Subthalamus
Thalamus
• 1 inch long mass of gray mater in each half of brain (connected
across the 3rd ventricle by intermediate mass)
• Relay station for sensory information on way to cortex
• Crude perception of some sensations
Boundries and relations of the thalamus:
Thalamus has 2 ends and 4 surfaces
 Anterior end : related to interventricular foramen
 Posterior end (Pulvinar): lies between splenium of corpus callosum above and
tectum of midbrain below
 Superior sufrace: related to lateral ventricle and fornix
inferior surface : related to A- hypothalamus & subthalamus
B- metathalamus that is formed of:
1- Lateral geniculate body (LGB): lower visual center
2- Medial geniculate body (MGB): lower auditory center
 medial surface: related to the 3rd, ventricle and in 70% of humans connected to the
opposite one by interthalamic adhesion
 lateral surface: related to internal capsulle
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Thalamic Nuclei
 Thalamus is divided into three nuclear groups by a Y- shaped band of fibers
called internal medullary lamina into:
1- Anterior nucleus
2- Medial nucleus
3- Lateral nucleus; is divided into two groups, ventral and dorsal:
A- Dorsal group: is divided into lateral dorsal , lateral posterior and pulvinar
B- Ventral group: divided into ventral nucleus and metathalamus
a- ventral nucleus: is divided into ventral anterior, ventral lateral, ventral
posterior ( ventral posterior medial and ventral posterior lateral)
b- metathalamus: is formed of LGB and MGB
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Thalamic Nuclei
 Functional classification of the thalamic nuclei into: according to the main
function of thalamic nuclei, the are divided into following groups:
1- 2 Specific Motor nuclei: VA and VL
2- 2 Specific sensory nuclei: VP and metathalamus
3- 2 limbic system nuclei: Anterior and medial nuclei
4- 3 Association Nuclei: the 3 dorsal nuclei ( LD, LP and pulvinar)
 Anterior and medial nuclei: are concerned with memory, mood, depth of feeling
and emotional behavior as the rest of limbic system
 Ventral anterior and ventral lateral nuclei: link the cerebellum and the basal
ganglia with the motor cortex for control of motor activity
 Dorsal group nuclei: form an indirect connection between specific thalamic
nuclei and their respective association cortical areas
 Ventral posterior lateral nucleus (VPLNT): receive all sensations from opposite
side of body
 Ventral posterior medial nucleus (VPMNT): receive all sensations from the
opposite side of the face
 Medial geniculate body: is an auditory relay nucleus
 Lateral geniculate body: is a visual relay nucleus
Thalamic syndrome:
• It occurs in patients during their recovery from thalamic infarction
•It is usually due to occlusion of the thalamogeniculate branch of the
posterior cerebral artery supplying the ventral posterior nucleus and the
geniculate bodies
•There is thalamic overreaction to pain and touch on the opposite side of
the body. A mild pain or touch is often excessive and agonizing and fails
to respond to powerful analgesics
Hypothalamus
The fornix divides the hypothalamus into medial and lateral regions:
A- Medial Region: contains 4 nuclear groups:
1. Pre optic area
2. Supraoptic nuclear group: contains 3 nuclei
a- anterior nucleus b- supraoptic nucleus
c- paraventricular nucleus
3. Tuberal nuclear group: contains 3 nuclei
a- Arcuate nucleus b- Ventromedial nucleus c- Dorsomedial nucleus
4- Mamillary group: posterior and contains the mamillary body and posterior nucleus
B- Lateral Region: contains the lateral hypothalamic nucleus
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Functions of Hypothalamus
1- Endocrine function: control the pituitary secretions:
A. Neurohypophysis ( post. Lobe of pituitary): Contains cell bodies of axons that
end in posterior pituitary where they secrete hormones
1. Supraoptic nucleus: secretes (antidiuretic hormone) (ADH)
2. Paraventricular nucleus: secretes oxytocin
B. Adenohypophysis ( anterior lobe of pituitary)
Hypothalamus secretes releasing and inhibiting hormones which control the
production of the anterior pituitary hormones.
2- Autonomic function: controls the brainstem and spinal cord autonomic
centers:
A. Parasympathetic centers: the anterior hypothalamic and preoptic nuclei (
vasodilatation, ↓ HR, ↓ BP,……)
B. Sympathetic centers: the posterior hypothalamic and lateral hypothalamic
nuclei ( vasoconstriction, ↑ HR, ↑BP,…….)
3- Temperature regulation:
A. Heat dissipation centers: sensitive to heat. In the anterior nucleus
B. Heat production: sensitive to cold. In the posterior nucleus
4- Regulation of food intake:
A. Satiety center: inhibits food intake. In ventromedial nucleus
B. Hunger center: stimulates food intake. In lateral hypothalamic nucleus
5- Regulation of water intake and excretion:
A. The lateral nucleus is the thirst center
B. ADH increases reabsorption of water from kidneys
6- Relation to emotions: it plays an important role in emotions since mamillary
body is part of the limbic system
7- Relation to sleep:
It has no direct role in regulation of sleep. But because fibers of reticular activating
system pass through it , it has a role in the arousal
Epithalamus
• Pineal gland
Pineal gland
– endocrine gland the
size of small pea
– secretes melatonin
during darkness
– promotes sleepiness
& sets biological
clock
• Habenular nuclei
– emotional
responses to odors
Subthalamus & CVO
• Subthalamus
– small area just inferior to thalamus
– work with basal ganglia, cerebrum & cerebellum to control
body movements
• Circumventricular organs
– in walls of 3rd & 4th ventricles
– monitor changes in blood chemistry because lack blood
brain barrier (parts of hypothalamus, pineal & pituitary
gland)
– sites of entry of HIV virus (Human Immunodeficiency
Virus) into brain
Basal Ganglia
• Connections to red nucleus, substantia nigra & subthalamus
• Input & output with cerebral cortex, thalamus &
hypothalamus
• Control large automatic movements of skeletal muscles
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Basal ganglia: components:
1- Corpus striatum: formed of caudate nucleus and lentiform nucleus
2- Subthalamic nucleus
3- Substantia nigra of midbrain
4- Thalamus: ventral anterior and ventral lateral
Function: the basal ganglia regulate the stereotyped motor activity (as walking &
swimming) and postural mechanism by influencing the brainstem and spinal cord motor
neurons
A: Caudate nucleus:
Formed of head, body and tail that related to lateral ventricle
it forms with the substantia nigra a circuit through which the dopamine inhibits the
activity of the caudate nucleus
• Parkinson’s disease: is associated with degeneration of substantia nigra with depletion
of dopamine resulting in over activity of caudate
This disease characterized by triad of symptoms ( tremor, rigidity, bradykinesia)
• Chorea : due to inhibition of caudate with over activity of dopamine secreting neurons
of subtantia nigra and manifisted by abnormal irregular and jerky movements of limbs
B: Lentiform nucleus is formed of 2 parts
1- globus pallidus is the medial part
2- Putamen is the lateral part: that forms together with caudate neostriatum
Note: the amygdaloid nucleus is anatomically included with the basal
ganglia
• it lies at the tail of the caudate nucleus at the temporal lobe deep to the
uncus
• Functionally it belongs to the limbic and olfactory systems
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Inputs To the Basal Ganglia System
Nearly all inputs arrive at the caudate and putamen.
All outputs go out from globus pallidus or from substantia nigra.
Parallel pathways in BG function in general motor
control, eye movements, cognitive functions,
and emotional functions.
Inputs:
1) Cerebral cortex: all lobes (sensory, motor and premotor) have projections
to striatum; most are (+) and use glutamate as neurotransmitter.
2) Substantia nigra (pars compacta): to striatum: (–) connections, uses dopamine.
3) Thalamus (intralaminar nuclei): to striatum: (+) and use glutamate.
Outputs of the Basal Ganglia System
1- Striatum (caudate and putamen): to globus pallidus (-) using (GABA)
2- Substantia nigra pars reticulata: to VL and VA thalamus; (-) using GABA.
3- Globus pallidus internal segment: to VL and VA thalamus; (-) using GABA.
VL/VA thalamus carries basal ganglia output to frontal lobe premotor cortex,
supplementary motor cortex, and primary motor cortex.
Intrinsic Basal Ganglia Connections
1) Direct pathway from the striatum to the globus
pallidus internal segment and
substantia nigra pars reticulata.
Pars reticularis projects inhibitory to thalamus
2) Indirect pathway from striatum to GP external
segment to subthalamus, to GP
internal segment to VA/VL thalamus.
Net effect of direct path is excitation of thalamus =
facilitation of movement
Net effect of indirect path is inhibition of thalamus =
inhibition of movement
•
Note : subthalmus can inhibit or excitate the globus
pallidus
Cerebral cortex
+
GLU
thalamus
+
GLU
+
GLU
GABA
GABA
Striatum
(caudate,
putamen)
Substantia nigra
(pars compacta
GABA
Globus
pallidus
GABA
subthalamus
Limbic System
History
Paul Broca (1824-1880): •
1878: “le grand lobe limbique”
Refers to a ring of gray matter on
the medial aspect of the cerebral
hemispheres.
James Papez (1883-1958): •
1930’s: defined a limbic system that might
underlie the relationship between emotion
and memory (Papez’ circuit).
Components of the limbic system
A. Nuclei of limbic system
1. Limbic lobe: formed of cingulate gyrus, parahippocampal gyrus and the uncus
2. Hippocampus with is continuous externally with parahippocampal gyrus
3. Hypothalamus: mainly mamillary body
4. Thalamic nuclei: Anterior nucleus and medial nucleus
5. Prefrontal cortex (personality center)
6. Amygdaloid nucleus
7. Habenular nucleus
B. Fibers connecting the nuclei:
1- Fornix originates in hippocampus and terminates in mamillary body
2Function of limbic system:
1. Emotional behavior: play major role in feeling, feeding, aggression, anger. These
emotional expressions are carried out through the hypothalamus via autonomic and
endocrine systems
2. Recent memory: the hippocamus plays a role in short term memory
3. olfaction
•Note: 1- Emotional brain--intense pleasure & intense pain
2- Strong emotions increase efficiency of memory
3- Alzheimer’s disease is due to due to degeneration of hippocampus
Hippocampal Formation
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Midbrain
•
•
One inch in length
Extends from pons to
diencephalon
• Cerebral aqueduct connects 3rd
ventricle above to 4th ventricle
below and divides the midbrain
into anterior part (cerebral
peduncle) posterior part
(tectum)
• The cerebral peduncle formed of
3 parts:
1- crus cerebri
2- Substantia nigra
3- Tegmentum
Midbrain in Section
• The Crus cerebri---clusters of motor & sensory fibers
• Substantia nigra---helps controls subconscious muscle activity
• Red nucleus-- rich blood supply & iron-containing pigment
– cortex & cerebellum coordinate muscular movements by sending
information here from the cortex and cerebellum
Dorsal Surface of Midbrain
• Corpora quadrigemina = superior & inferior colliculi
– coordinate eye movements with visual stimuli
– coordinate head movements with auditory stimuli
Medulla Oblongata
•
•
•
•
•
Continuation of spinal cord
Ascending sensory tracts
Descending motor tracts
Nuclei of 5 cranial nerves
Cardiovascular center
– force & rate of heart beat
– diameter of blood vessels
• Respiratory center
– medullary rhythmicity area sets basic rhythm of breathing
• Information in & out of cerebellum
• Reflex centers for coughing, sneezing, swallowing etc
Ventral Surface of Medulla Oblongata
• Ventral surface bulge
– pyramids
– large motor tract
– decussation of most fibers
• left cortex controls right
muscles
• Olive = olivary nucleus
– neurons send input to
cerebellum
– proprioceptive signals
– gives precision to
movements
Dorsal Surface of Medulla Oblongata
• Nucleus gracilis & nucleus cuneatus = sensory neurons
– relay information to thalamus on opposite side of brain
• 5 cranial nerves arise from medulla -- 8 thru 12
Hemispheric Lateralization
• Functional
specialization of each
hemisphere more
pronounced in men
• Females have larger
connections between 2
sides
• Damage to left side
produces aphasia
• Damage to same area
on right side produces
speech with little
emotional inflection