Diencephalon Flashcards
What are the five divisions of the diencephalon?
Describe its embryologic origin.
Epithalamus, Dorsal Thalamus, Ventral Thalamus, Subthalamus, Hypothalamus.
It arises from between the telencephalon and mesencephalon.
To which subdivision do the following structures belong:
Habenula
Zona Incerta
Infundibulum
Medullary Laminae
Epithalamus
Subthalamus
Hypothalamus (the stalk of the pituitary)
Dorsal thalamus
Which contributor to the circle of willis does not supply the thalamus?
Middle Cerebral Artery
What are the functions of the (dorsal) thalamus?
- Relay sensory information to cortex.
- Relay motor information to cortex.
- Integrate different sensory modalities.
- Relay emotional/affective information to cortex.
- Support the “Papez” limbic circuit.
- Influence alertness/arousal/sleep.
What is the function of a thalamic nucleus?
How are they grouped? Try to name the 7 groups.
A thalamic nucleus is a site of relay between a peripheral signal and a site somewhere in the cerebral cortex.
We generally divide them by their anatomic locations within the thalamus: anterior group, lateral-ventral, lateral-dorsal, medial, midline, intralaminar, reticular. Note that the last three do not relay to any single specific site (“diffuse”)
Ventral Posterolateral Nucleus (VPL)
What is the input?
What is the output?
To what group does it belong?
Ventral Posterolateral Nucleus (VPL)
Input from spinothalamic and medial lemniscus tracts (all body sensation)
Relay onto the primary somatosensory nucleus (3/1/2)
It is in the lateral-ventral group.
Anterior Nuclear Group
What is the input?
What is the output?
What is the function of this relay?
Anterior Nuclear Group
Input from the mammilary body.
Relay to the cingulate gyrus.
Part of the limbic system: Alertness, learning, memory.
Ventral Posteromedial Nucleus (VPM)
What is the input?
What is the output?
To what group does it belong?
Ventral Posteromedial Nucleus (VPM)
Input from the trigeminal nuclei (all head sensation)
Relay onto the primary somatosensory nucleus (3/1/2)
It belongs to the lateral-ventral group.
Lateral Posterior Nucleus (LP)
What is the input?
What is the output?
To what group does it belong?
Lateral Posterior Nucleus (LP)
Input is from the parietal cortex.
Relay is back to the parietal cortex.
It is part of the lateral-dorsal group. It works in concert with the pulvinar nucleus.
Lateral Dorsal Nucleus (LD)
What is the input?
What is the output?
To what group does it belong?
Lateral Dorsal Nucleus (LD)
Input is from the cingulate gyrus.
Ouptut is back onto the cingulate gyrus.
It belongs to the lateral-dorsal group. Despite this, it works more in concert with anterior nuclear nuclei (limbic) than the pulvinar.
Ventral Anterior Nucleus (VA)
What is the input?
What is the output?
To what group does it belong?
Ventral Anterior Nucleus (VA)
Input is from the globus pallidus (basal ganglia)
Relay is to the premotor cortex (6)
It belongs to the lateral-ventral group.
Ventral Lateral Nucleus (VL)
What is the input?
What is the output?
To what group does it belong?
Ventral Lateral Nucleus (VL)
Input is from the dentate nucleus (cerebellum).
Output is to the motor & premotor cortices (4/6).
It belongs to the lateral-ventral group.
Medial Group Nuclei** **(MD)
What is the input?
What is the output?
What is their function?
Medial Group Nuclei (MD)
Input from the limbic system: Amygdala, Hypothalamus, (Olfactory cortex)?
Relays to the prefrontal cortex.
Thought to play a role in memory, as well as attention, planning, and abstract thought.
Pulvinar
What is the input?
What is the output?
To what group does it belong?
Pulvinar
Input is from the spinal cord and parieto-occipito-temporal cortex.
Relay is back to the POT cortex.
It belongs to the lateral-dorsal group. It is apparently important to sensory processing.
Lateral Geniculate Nucleus__ (LGN)
What is the input?
What is the output?
To what group does it belong?
Lateral Geniculate Nucleus (LGN)
Input from the retinas.
Relay onto the visual cortex (17)
It belongs to the lateral-ventral group.
