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Year 2 Anatomy > Thalamus and Internal Capsule > Flashcards

Thalamus and Internal Capsule Flashcards

1
Q

What is the thalamus?

A

4x1.5x1.5cm egg-shaped mass of grey matter
Forms major part of the diencephalon
2 thalami- situated on each side of the third ventricle
Caudate nucleus sits closley on top of it
The posterior end of the thalamus is expanded to form the pulvinar

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2
Q

Label this

A
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3
Q

What are the medial and lateral relations of the thalamus?

A

Medial: forms part of the lateral wall of the third
ventricle. Connected to the opposite thalamus by a
band of gray matter called the interthalamic adhesion
Lateral: internal capsule

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4
Q

What are the inferior and superior relations of the thalamus?

A

Inferior -continuous with the tegmentum of the midbrain
Superior - Lateral to medial- caudate nucleus, stria terminalis, thalamostriate vein, fornix

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5
Q

What is the lateral ventricle?

A

Lateral ventricle loacted within the cerebral hemisphere
They communicate via the interventricular foramen to the third ventricle, which is a signular structure in the midline
The lateral and the medial recess further drain to the subarachnoid space.

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6
Q

Label and describe the structure of the lateral ventricle

A

red line is where the thalamus would sit
One lateral ventricle in the left hemisphere, one in the right. The lateral ventricles have three horns which project into the frontal, occipital, and temporal lobes.

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7
Q

What is shown by the black arrow? Describe it

A

Internal medullary lamina= sheet of white matter
dividing grey matter of the thalamus into medial and
lateral halves
The internal medullary lamina splits into a Y shape

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8
Q

The thalamus is divided into anterior, medial and posterior parts
Describe the anterior part of the thalamus

A

Contains anterior thalamic nuclei
Receives afferents from the mammillothalamic tract
Has connections w the cingulate gyrus + hypothalamus.
Function - emotional tone and recent memory.

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9
Q

Label this anterior part of the thalamus

A
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10
Q

Describe the medial part of the thalamus

A

Contains the dorsomedial nucleus
Receives afferents from Amygdaloid complex
Has connections w prefrontal cortex + hypothalamic nuclei.
Interconnected w all other thalamic nuclei.
Function: integrates somatic, visceral, and olfactory info, and relates this to emotion and subjective states.

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11
Q

Label the medial parts of the thalamus

A
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12
Q

Describe the lateral part of the thalamus

A

The lateral part of the thalamus contains the dorsal Tier of nuclei= lateral dorsal, lateral posterior nucleus and pulvinar.
This has interconnections with –
* other thalamic nuclei, parietal lobe, cingulate gyrus, occipital and temporal lobes.

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13
Q

Label this

A
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14
Q

What does the ventral tier of the nuclei contain?

A

Ventral anterior nucleus
Ventral lateral nucleus
Ventral posterior nucleus

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15
Q

What are the afferents and efferents of the Ventral anterior and Ventral lateral nuclei?

A

Receives afferents from:
–substantia nigra
–Globus pallidus
–Dentate nucleus (VL)
Sends efferents to:
–premotor cortex –Area 4,6
* Influences the activities of the
motor cortex.

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16
Q

Describe the ventral posterior nuclei

A
17
Q

Label this

A
18
Q

What are the afferents and efferents of the VPL nucleus?

A

Afferents
–Medial lemniscus, Spinal lemniscus
Efferents
–Parietal lobe, Post central gyrus

Function: Relay station for nociception and proprioceptive
sensations from contra lateral body except face

19
Q

What are the afferents and efferents of the VPM nucleus?

A

Afferents
– Trigeminal lemniscus, Solitary nucleus
* Efferents
– Parietal lobe, Post central gyrus through superior thalamic radiation
Function: Relay station for nociception and proprioception from contralateral face and for taste

20
Q

Relate this diagram to the VPM and VPL, as well as what they project to

A
21
Q

There are lateral and medial geniculate bodies. Describe medial geniculate

A

A swelling on the posterior thalamus beneath the pulvinar
Part of the auditory pathway
* Afferent - inferior brachium from the inferior colliculus
* Efferent - auditory radiation to the auditory cortex of the
superior temporal gyrus
(41,42 areas in the sup. temporal gyrus)

22
Q

There are lateral and medial geniculate bodies. Describe lateral geniculate

A

Part of visual pathway
* Swelling on the undersurface of the pulvinar of the thalamus
* 6 layers of nerve cells
* Afferents- optic tract
* Efferent - Optic radiation, which passes to the visual cortex of the occipital lobe.

23
Q

What is the blood supply to the thalamus?

A

Through branches of -
* Posterior communicating arteries
* Basilar artery
* Posterior cerebral arteries

24
Q

Label this to show the blood supply to the thalamus

A
25
Q

What is important clinical considerations w the thalamus?

A

1) thalamic nuclei are small so that lesions producing highly
specific effects are uncommon
2) Thalamic lesions frequently are accompanied by symptoms
from damage to closely related internal capsule, caudate
nucleus and lentiform nucleus

26
Q

Thalamic sydrome can cause contralateral hemianesthesia and Hyperalgesia. Describe these

A
  1. Contralateral hemianesthesia (The inability to feel sensations from touch on one side of the body)
    * Due to damage to VPL and VPM
    * all somatic sensory modalities affected: light
    touch, proprioception, 2-point discrimination, vibration, and nociception
  2. Hyperalgesia or causalgia (spontaneous pain with no stimulation) - seen after a recovery from damage to
    VPL and VPM (days to months). Pain can be severe and intractable.
27
Q

What else is caused by Thalamic sydrome?

A
  1. Contralateral homonymous hemianopia- Lateral Geniculate Bodies affected
  2. Movement disorders - damage of VA/VL nuclei (cerebellum
    and basal ganglia project to VA and VL). Symptoms are seen contralateral to the side of the lesion.
28
Q

Describe the medial part of the thalamus

A

Contains the dorsomedial nucleus
Receives afferents from Amygdaloid complex
Has connections w prefrontal cortex + hypothalamic nuclei.
Interconnected w all other thalamic nuclei.
Function: integrates somatic, visceral, and olfactory info, and relates this to emotion and subjective states.

Year 2 Anatomy (17 decks)

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