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CHAPTER 8
Thalamus
Thalamus In Situ
138
Thalamic Nuclei
139
Thalamus in Horizontal Section
141
Thalamus in Coronal Section
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Thalamus
THALAMUS IN SITU
Location
Paired, medially placed, deep egg-shaped nuclear structures that form part of
the lateral wall of the 3rd ventricle
Architecture
Composed of multiple nuclei, which receive input from many cortical and
subcortical structures
Function
Functions as the “gateway to the cortex.” Sensory input, other than olfaction,
relays through the thalamus before reaching the cortex. All output to the
cortex from the cerebellum and basal ganglia relays through the thalamus.
The thalamus also relays limbic input to the cortex
Clinical
Significance
Due to its multiple functions, damage to the thalamus can cause many
problems, including sensory abnormalities, visual-field deficits, and behavioral
changes
Lesions to the sensory area can cause numbness on the contralateral body and
face
Interventricular foramen
Corpus callosum (cut)
Head of caudate nucleus
3rd ventricle
Choroid plexus
Internal cerebral v.
Superior
thalamostriate v.
(vena teminalis)
Pes hippocampi
Inferior horn of
lateral ventricle
Dentate gyrus
Collateral
eminence
Hippocampus
Fimbria of
hippocampus
Septum pellucidum
Columns of fornix
Anterior tubercle
Stria terminalis
Interthalamic adhesion
Stria medullaris
Habenular tribone
Pulvinar (lifted)
Lateral geniculate body
Medial geniculate body
Brachium of
superior colliculus
Posterior
commissure
Habenular
commissure
Pineal gland
Collateral
trigone
Brachium of
inferior colliculus
Superior colliculus
Inferior colliculus
Cerebellum
Calcar avis
Posterior horn
of lateral ventricle
Calcarine
sulcus (fissure)
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Thalamus
THALAMIC NUCLEI
• The thalamus is composed of many nuclei, which have motor, sensory, and limbic
connections.
• Some nuclei are nonspecific in nature.
NUCLEUS
INPUT(S)
OUTPUT(S)
FUNCTION
Sensory Nuclei
Ventroposterolateral
(VPL)
Spinothalamic tract
Medial lemniscus
Primary sensory
cortex
Somatic sensation
for contralateral
body
Ventroposteromedial
(VPM)
Trigeminothalamic tract,
pontine taste area
Primary sensory
cortex
Somatic sensation
for contralateral
face, taste
Medial geniculate
(MGN)
Brachium of the inferior
colliculus
Primary auditory
cortex
Hearing
Lateral geniculate
(LGN)
Optic tract
Primary visual
cortex
Vision
Pulvinar
Lateral geniculate body
(LGB), medial geniculate
body (MGB), superior and
inferior colliculi
Visual association
cortex
Visual processing
Motor Nuclei
Ventrolateral (VL)
Cerebellum and basal
ganglia
Primary motor
cortex
Modulation and
coordination of
movement
Ventroanterior (VA)
Basal ganglia
Premotor cortex
Initiation and
planning of
movement
Ventrointermedial (VI)
Cerebellum
Primary motor
cortex
Coordination of
movement
Limbic and Nonspecific Projection Nuclei
Anterior (Ant)
Mammillothalamic tract
Cingulate cortex
Memory storage
and emotion
Mediodorsal (MD)
Temporal lobe, amygdala,
hypothalamus
Prefrontal cortex
Motivation, drive,
emotion
Centromedian (CM)
Slow pain pathways
Nonspecific
cortical
projections
Emotional content
of pain
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THALAMIC NUCLEI
continued
Thalamocortical
radiations
Central sulcus
CM
LD
LP
MD
VA
VI
VL
VPL
VPM
Centromedian
Lateral dorsal
Lateral posterior
Medial dorsal
Ventral anterior
Ventral intermedial
Ventral lateral
Ventral posterolateral
Ventral posteromedial
Internal medullary lamina
Intralaminar nuclei
Anterior nuclei
Other medial nuclei
Midline (median) nuclei
MD
Interthalamic adhesion
LD
LP
VA
Pulvinar
VL
VI
CM
VPL
From globus pallidus
and substantia nigra
Reticular nucleus
(pulled away)
Acoustic pathway
From
cerebellum
Somesthetic from body
(spinothalamic tract and medial lemniscus)
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Medial geniculate body
VPM
Lateral geniculate body
Optic tract
Somesthetic from head (trigeminal nerve)
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Thalamus
THALAMUS IN HORIZONTAL SECTION
• Thalami form the lateral walls of the third ventricle.
• Posterior limb of the internal capsule separates thalamus from the lentiform nucleus.
• Pulvinar is demonstrated in the artwork below.
Frontal lobe
External capsule
Anterior limb of
internal capsule
Claustrum
Extreme
capsule
Level of section
(head of caudate
and mid thalamus)
Head of caudate nucleus
Genu of corpus
callosum
Genu of
internal
capsule
Insular
cortex
Anterior
horn of
lateral
ventricle
Posterior limb of
internal capsule
Transverse temporal
gyrus of Heschl
Auditory radiations
Tail of caudate nucleus
Temporal lobe
Optic
radiation
Temporal pole of
lateral ventricle
Choroid plexus
Fimbria of fornix
Occipital lobe
Columns
of fornix
Third
ventricle
Globus pallidus
Putamen
Splenium of the
corpus callosum
Thalamus
Pulvinar
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Thalamus
THALAMUS IN CORONAL SECTION
STRUCTURE
ANATOMIC NOTES
FUNCTIONAL SIGNIFICANCE
Thalamus
Individual nuclei are anatomically
separated. The thalamus defines
the borders of the 3rd ventricle
LGN of the
thalamus
Comma-shaped, lateral nucleus of
the thalamus
Serves as the visual relay center from
the optic tract to occipital cortex.
Lesions can cause visual field defects
MGN of the
thalamus
Medial to the lateral geniculate
nucleus
Serves as the auditory relay center
from the inferior colliculus to auditory
cortex
MDN of the
thalamus
Most dorsal and medial nucleus;
forms part of the wall of the 3rd
ventricle
Part of the limbic system
CM thalamus
Located ventral to the MDN
Involved in the central modulation
and perception of pain
Lateral
thalamus
Contains multiple nuclear structures,
including the VL and VPL
Involved in motor and sensory relays
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Thalamus
THALAMUS IN CORONAL SECTION
continued
Body of corpus callosum
Cingulate cortex
Interventricular
foramen of Monro
Columns of fornix
Third ventricle
Body of lateral
ventricle
Cingulum
Stria terminalis
Body of caudate
nucleus
Level of section
(midthalamus)
Medial dorsal thalamus
Insular cortex
Lateral thalamus
Lateral geniculate nucleus
Centromedian thalamus
Tail of the caudate nucleus
Hippocampal
formation
Medial
geniculate
nucleus
Cortex of
cerebellum
Entorhinal
cortex
Superior
cerebellar peduncle
Pons (floor of
fourth ventricle)
Inferior cerebellar
peduncle
Medulla
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