Download Hypothalamus

Diencephalon:
Thalamus and Hypothalamus
Diencephalon
• Relay between the brainstem & cerebral cortex
• Dorsal-posterior structures
– Epithalamus
• Habenular nuclei – integrate smell & emotions
• Pineal gland – monitors diurnal / nocturnal rhythm
– Thalamus
– Metathalamus
• Medial geniculate body – auditory relay
• Lateral geniculate body – visual relay
• Ventral-anterior structure
– Hypothalamus
Position
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Position: Lies between midbrian and cerebrum, almost
entirely surrounded by cerebral hemisphere
Subdivision
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Doral thalamus
Metathalamus
Epithalamus
Subthalamus
Hypothalamus
lateral ventricle third ventricle
Anterior Commissure
Interventricular foramen
Optic tract
Click
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( foramen of Monro )
Lamina Terminaris
Mammillary Body
Infundibulum
Sulcus terminalis
Stria terminalis terminal vien
Anterior thalamic tubercle Anterior
thalamic nucleus
sulcus
Ant. tubercle
Stria medullaris thalami
Massa intermedia
( interthalamic
adhesion )
Hypothalamic sulcus
Hypothalamus
Posterior Commissure
Habenula trigone
Habenula nucleus
Mammillary body
Optic chiasm
infundibulum
Turber cinereum
Dorsal thalamus
External features
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A large egg-shaped
nucleus mass,
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Anterior end called
anterior thalamic tubercle,
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Posterior end called
pulvinar
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Right and left portion of
thalamus are joined by
interthalamic adhesion
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Floor－hypothalamic
sulcus
Subdivision
Principal Nuclei
Common
abbreviation
Ant. nuclear group
Med. nuclear group
Lat. nuclear group
Dorsal tier
Lateral dorsal
LD
Lateral posterior
LP
Pulvinar
Ventral tier
Ventral anterior
VA
Ventral lateral
VI
Ventral posterior
VP
Ventral posterolateral
VPL
Ventral posteromedial
VPM
Classification of nuclei of dorsal thalamus
Three nuclear group divided by
internal medullary lamina
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Anterior nuclear group
Medial nuclear group
Lateral nuclear group
internal medullary lamina
Med. nuclear group
Dorsal tier
Ant. nuclear group
Pulvinar
Medial geniculate
body (MGN)
Ventral anterior
Ventral lateral
Ventral posterior nucleus (VP)
Lateral geniculate body (LGN)
Ventral posterolateral (VPL)
Ventral posteromedial (VPM )
Function of the Thalamus
• Sensory relay
– ALL sensory information
(except smell)
• Motor integration
– Input from cortex, cerebellum
and basal ganglia
• Arousal
– Part of reticular activating
system
• Pain modulation
– All nociceptive information
• Memory & behavior
– Lesions are disruptive
Input to the Thalamus
Input to the Thalamus
Metathalamus
Vision and Hearing
Input to the Thalamus
Sensory relay - Ventral posterior group
all sensation from body and head, including pain
Input to the Thalamus
Motor control and integration
Projections from the Thalamus
Behavior and emotion
connection with hypothalamus
Special relay nuclei
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Vent. lateral (VL) Receiving dentate nucleus to motor cortex
Vent. anterior nucleus (VA)
Receiving globus pallidus and substantia nigra to motor cortex
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Vent. posteromedial nucleus (VPM)
－receives trigeminal lemniscus and taste fibers
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Vent. posterolateral nucleus (VPL)
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receives medial lemniscus and spinal lemniscus
Projects to first somatic sensory area via central thalamic radiation
 Medial, lateral geniculate bodies
Thalamus:
coronal view
Dorsomedial nucleus has
reciprocal connections to
prefrontal cortex.
Concerned with judgment,
decision making, memory
and behavior.
Mediodorsal nucleus
Internal capsule
Thalamus
Ventral
lateral
nucleus
Mediodorsal nucleus
VL nucleus has reciprocal
connections with primary motor
cortex. It receives input from
cerebellar nuclei.
With VA nucleus (which receives
input from basal ganglia)
contributes to planning and
control of movement.
Internal capsule
Metathalamus
Lateral geniculate body (LGN)
Medial geniculate body (MGN)
Metathalamus
Metathalamus
Medial geniculate body
(MGN)
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Relay station of audition
Receive fibers from
inferior colliculus
Projects to auditory area
via acoustic radiation
Lateral geniculate body
(LGN)
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Relay station of vision
Receive fibers from optic
tract
Projects to visual area via
optic radiation
Functional subdivisions
Nonspecific relay nuclei receive input from many
converging sources and in turn project widely to the
association areas of cerebral cortex
 Anterior nuclear group
 Medial nuclear group(mediodorsal)
 Dorsal tier of lateral nuclear group
Association nuclei(reticular nuclei)
receive afferents from rhinencephalon and reticular
formation of brain stem, project mainly to
hypothalamus and corpus striatum
 Midline nucleus group(interthalamic connection):
visceral afferent , hypothalamus
 Intralaminar nuclear group (centromedian): pain,
consciousness
 Thalamic reticular nucleus
Thalamus:
axial view
Descending upper motor neurons
Cerebral peduncles
Internal capsule
Thalamus:
axial view
Thalamus:
Pons
sagittal view
Thalamus:
sagittal view
Thalamus:
coronal view
Thalamus:
coronal view
3rd ventricle
Thalamus:
coronal view
Internal capsule
Thalamus:
coronal view
Cerebral
peduncles
Internal capsule
Thalamus:
blood supply
Corona Radiata & Internal capsule
Int. Capsule: Thalamic radiation, pyramidal &
extrapyramidal
Subthalamus
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Transition zone
between diencephalons
and tegmentum of
midbrain
Contain subthalamic
nucleus, parts of red
nucleus and substantia
nigra, zona incerta
Epithalamus
Includes
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Thalamic medullary
stria
Habenular trigone
Habenular
commissure
Pineal body
posterior commissure
Hypothalamus
Position－lies ventral to thalamus
Boundaries
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Superiorly: hypothalamic sulcus
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Inferiorly:
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optic chiasma
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tuber cinereum
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Infundibulum
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mamillary body
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Anterior: lamina terminalis
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Posterior: continues with
midbrain tegmentum
Paraventricular nucleus
Paraventriculohypophyeal
tract
Supraoptic nucleus
Supraopticohypophyseal
tract
Mamillary nucleus
arcuate nucleus
tuberoinfundibular tract
infundibulum
anterior lobe of hypophsis
posterior lobe of hypophysis
Hypothalamus
THE HYPOTHALAMUS
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Lateral zone
No discrete nuclei
Regulation of food and water
intake
•Medial zone
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Tuberal region (middle reg.)
VM – satiety center (lesion
produces hyperphagia +
obesity)
Arcuate nc. - delivers peptides
to the portal vessels
•Well defined nuclei
•Chiasmatic region (anterior region) Mamillary region (posterior
reg.)
•hormone release- (SO,PV)
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•Cardiovascular function (Ant.)
•Circadian rhytms (SCH)
•Body temperature (Preoptic nc.)
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Posterior nc.- elevating of
blood pressure, pupillary
dilatation, body heat
conservation
Mammillary ncc. – memory
formation (fornix)
Hypothalamus:
sagittal view
Hypothalamus --connection
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Connects with limbic system
Connects with brainstem and spinal cord
Connects with dorsal thalamus
Connects with hypophysis
Hypothalamus --connection
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Supraoptic nucleus →supraoptic nucleus
(ADH) →supraopticohypophyseal tract
→posterior lobe of hypophysis
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Paraventricular nucleus → paraventicular
nucleus (oxytocin) →paraventriculohypophyseal
tract→posterior lobe of hypophysis
Paraventricular nucleus
Paraventriculohypophyseal tract
Supraoptic nucleus
Supraopticohypophyseal trac
Inferior hypophyseal a.
posterior lobe of hypophysis
Hypophyseal v.
Parvicellular neurons in the
arcuate nucleus and nearby
region of the walls of the third
ventricle secrete releasing and
inhibiting hormones →
tuberoinfundibular tract
→portal vein of hypophsis →
anterior lobe of hypophsis
Tuberoinfundibular tract
Median eminence
Portal v.
Superior hypophyseal a.
anterior lobe
Hypophyseal v.
Hypothalamus:
coronal view
Pre-Optic Region
Gonadotropic releasing
hormone
Sexual arousal, appetite,
reproduction
Hypothalamus:
coronal view
Suprachiasmic Region
Secrete ADH, oxytocin
Transported via axons to
posterior pituitary
(hypophysis)
Hypothalamus:
coronal view
Regulates thirst
Hypothalamus:
coronal view
Body temperature
Circadian rhythms
Hypothalamus:
coronal view
Tuberal Region
Satiety
Hypothalamus:
coronal view
Regulates prolactin
and growth hormone
β endorphin for pain
Hypothalamus:
coronal view
Mammillary region
Limbic system
Hypothalamus:
coronal view
Hypocretin
(orexin)
Narcolepsy,
reward