Diencephalon

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Diencephalon
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Diencephalon

• Thalamus ? dorsal thalamus
• Hypothalamus
• pituitary gland
• Epithalamus
• habenular nucleus and commissure
• pineal gland
• Subthalamus ? ventral thalamus
• subthalamic nucleus (STN)
• field of Forel

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Diencephalon
dorsal surface
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Diencephalon
ventral surface
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Diencephalon Medial Surface
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THALAMUS
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Classification of Thalamic Nuclei
I. Lateral Nuclear Group II. Medial Nuclear
Group III. Anterior Nuclear Group
IV. Posterior Nuclear Group V. Metathalamic
Nuclear Group VI. Intralaminar Nuclear Group
VII. Thalamic Reticular Nucleus
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Classification of Thalamic Nuclei
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15 mm
12 mm
Distance from anterior thalamic pole
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4.02 mm
2.02 mm
Distance from anterior thalamic pole
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LATERAL NUCLEAR GROUP
Ventral Nuclear Group Ventral
Posterior Nucleus ventral posterolateral
nucleus ventral posteromedial nucleus
ventral posteroinferior nucleus
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LATERAL NUCLEAR GROUP
Ventral Lateral Nucleus (VL) - pars oralis
- pars caudalis - pars medialis
Ventral Anterior Nucleus (VA) - pars
parvicellularis - pars magnocellularis
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LATERAL NUCLEAR GROUP
Prefrontal
SMA MI, PM SI
Ventral Nuclear Group
TTT
SNr
ML, STT
Cbll
GPi
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LATERAL NUCLEAR GROUP
Dorsal or Lateral Nuclear Group Lateral
Dorsal Nucleus Lateral Posterior Nucleus
Pulvinar
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LATERAL NUCLEAR GROUP
cingulate gyrus, precuneus
Somesthetic Association Area
Visual Association area
HF
SC, Pretectal
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MEDIAL NUCLEAR GROUP
Dorsomedial Nucleus - pars
magnocellularis - pars parvocellularis
- pars paralaminaris - pars
densocellularis Midline Nuclear Group
Paratenial Nucleus Reunience Nucleus
Submedial Nucleus Rhomboid Nucleus
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ANTERIOR NUCLEAR GROUP anteroventral nucleus
(AV, A.pr.) anterodorsal nucleus (AD,
A.d.) anteromedial nucleus (AM, A.m.) POSTERIOR
NUCLEAR GROUP suprageniculate nucleus (SG,
Li.) nucleus limitans (Lim, Li.) posterior
nucleus (PO, Li.por.)
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MEDIAL ANTERIOR NUCLEAR GROUP
Prefrontal Cortex
Frontal Eye Field
MB, HF
Medial Frontal Gyrus
cingulate gyrus
Basal forebrain
SNr, SC, RF
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METATHALAMIC NUCLEAR GROUP
Medial Geniculate Nucleus ventral nucleus
dorsal nucleus medial nucleus Lateral
Geniculate Nucleus dorsal nucleus ventral
nucleus
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INTRALAMINAR NUCLEAR GROUP
Rostral Intralaminar Nuclei central lateral
nucleus central medial nucleus paracentral
nucleus Caudal Intralaminar Nuclei centre
median nucleus
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THALAMIC RETICULAR NUCLEUS
Cerebral Cortex
Thalamocortical Neuron
Thalamic Reticular Nucleus
Subcortical Structure
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Summary of Thalamic Connectivity
I. Sensory Input general sensation
special sensation taste, equilibrium, hearing,
vision II. Motor Input cerebellum, basal
ganglia III. Reticular Formation
IV. Limbic System mammillary nucleus
hippocampal formation
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Sensory Input
(1) General Sensation 1. Medial lemniscus
VPLc ----------- S I, S II 2.
Spinothalamic tract VPLc ----------- S
I, S II 3. Trigeminothalamic tract
VPM ------------- S I, S II
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Sensory Input
(2) Taste sensation VPM pc
------- gustatory area (Brodmann area 43) (3)
Sense of equilibrium VPLo ---------- S
I (4) Auditory sensation MGv ----------- A
I (Brodmann area 41, 42) MGd ----------- A
II (5) Vision LGd ---------- V I
(Brodmann area 17) Pi, Pl ---------- V I,
V II (Brodmann area 17, 18, 19)
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Motor Input
(1) Cerebellum VLc, VPLo
---------- M I (Brodmann area 4), Premotor
area (2) Basal ganglia 1. GPi (internal
segment of globus pallidus) VL
-------- SMA (supplementary motor area)
VA ------- frontal cortex
2. SNr (pars reticularis of substantia nigra)
VL, VA - fronal cortex
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Reticular Formation Limbic System
Reticular formation rostral intralaminar
nuclei ----- diffuse cortical areas
thalamic reticular nucleus -----
adjacent thalamic nucleus Limbic System
Mammillary Body AV, AD, AM -----
cingulate gyrus Hippocampal Formation
AV, AD, AM ----- cingulate gyrus LD
------------------ cingulate gyrus, precuneus
Re ------------------- medial cortex,
entorhinal cortex
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Clinical Syndromes of the Thalamus
Posterolateral thalamic syndromes
sensory disorders Thalamic
(Dejerine-Roussy) syndrome ----- VP
nucleus - pain Medial thalamic syndromes
disorders of consciousness
thalamic neglect, thalamic amnesia,
akinetic mutism Anterolateral thalamic
syndromes motor disorders
paresis, ataxia, motor incoordination, dysphagia
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Thalamic (Dejerine-Roussy) Syndrome
Joseph Jules Dejerine (1849-1917)
Gustave Roussy (1874-1948)
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Visual (Optic) Pathway
Modality Vision
Receptor Photoreceptor
Cell of Retina
Cranial Nerve II (Optic nerve)
1st Neuron Bipolar Cell
2nd Neuron Ganglion Cell
optic nerve
optic chiasm optic
tract 3rd Neuron Lateral
Geniculate Nucleus
optic radiation Termination
Visual Areas (V I, V II)
Brodmann area 17 (V I), 18, 19 (V II)
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RETINA - Pars Nervosa
1. Pigment Epithelium - retinal
detachment 2. Neuronal Layer (1)
Photosensitive Cell Layer Rod Cell,
Cone Cell (2) Bipolar Cell Layer
Bipolar Cell Horizontal Cell
Amacrine Cell (3) Ganglion Cell Layer
Ganglion Cell Optic Nerve (II)
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Visual Pathway
1. Optic nerve 2. Optic chiasm 3. Optic tract 4.
Lateral geniculate body 5. Optic
radiation 6. Visual cortex
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Visual (Optic) Pathway
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Visual Pathway Lateral Geniculate Nucleus
(LGd)

Dorsal Nucleus (LGd) Magnocellular Part
1, 2 Parvocellular Part 3, 4, 5, 6
contralateral afferents 1, 4, 6
ipsilateral afferents 2, 3, 5 Ventral
Nucleus (LGv) part of thalamic
reticular nucleus
dorsolateral
ventromedial
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Optic Radiation (Geniculocalcarine Tract)
Meyers loop
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Clinical Features of Visual Pathway Lesion
1. optic nerve 2. optic chiasm 3. optic tract 4.
5. optic radiation A. unilateral blindness B.
bitemporal hemianopsia C. left homonymous
hemianopsia D. left inferior homony- mous
quadranopsia E. left superior homony- mous
quadranopsia
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Signs of Visual Pathway Lesion
Optic nerve - ipsilateral blindness Optic
chiasm - bitemporal hemianopsia Optic tract
- contralateral homonymous hemianopsia Optic
radiation - contralateral homonymous
quadranopsia - intact light reflex Visual
Cortex - contralateral homonymous
quadranopsia - macular sparing
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Visual Field Defect
left inferior optic radiation lesion right
superior quadranopsia
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Hypothalamus ? Limbic System
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Epithalamus ? Limbic System
Habenular Nucleus Medial Habenular
Nucleus Lateral Habenular
Nucleus Habenular Commissure Pineal Gland
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Subthalamus ? Basal Ganglia
Subthalamic nucleus zona incerta Field of Forel
H ansa lenticularis
H1 thalamic fasciculus H2 lenticular
fasciculus