NeuroTeach 46 - Diencephalon

ETHOS Diencephalon!!!

2) Location - around the 3rd ventricle The cavity of the diencephalon is ----- the 3rd ventricle All of the structures of the diencephalon are around the 3rd ventricle, so the cavity of the diencephalon is the 3rd ventricle.
3) Embryology
- prosencephalon


4) Components (ETHOS) Epithalamus (habenular & pineal) - sleep-wake cycle Thalamus - relay center for sensory information Hypothalamus (mammillary body & tuber cinereum) - autonomic function & endocrine system Optic nerve Subthalamus - inhibition of involuntary movements


5) Epithalamus “melatonin control”

6) Function - connects limbic system to other parts of the brain - controls the circadian rhythm
7) Components - PHAS Pineal gland HAbenula HAbenular commissure Stria medullaris


8) Relation between pineal gland & habenular commissure & posterior commissure

9) Relation between pineal gland & habenula & stria medullaris

10) Thalamus
“the major component of diencephalon”

11) Structure
Thalami nuclei are divided by “Y” shaped white matter (internal medullary lamina)
- anterior, medial, and lateral nuclear groups
Pulvinar: Post end of Pos Pole of thalamus
12) Function
Major sensory relay center
13) Connections
Thalamic Radio – ABCDEFGHI (anticlockwise)


14) 🅐 Anterior Nucleus
Alertness, Attention, Affect, Acute memory *these are the main functions of limbic system – Papez circuit Afferent: mammillary body Efferent: cingulate gyrus

15) 🅑Ventral anterior nucleus
Basal ganglia Afferent: globus pallidus and substantia nigra Efferent: Broadmann area 6 (prefrontal and premotor cortex)

16) 🅒 Ventral lateral nucleus
Co-ordination & Cerebellum Afferent: cerebellum (dentate nucleus) & basal ganglia Efferent: Broadmann area 4 (primary motor cortex)

17) 🅓 Ventral posterior nucleus Dermatome (sensory) Afferent: - Ventro-postero-medial (VPM) nucleus: trigemino-thalamic tract & solitario-thalamic tract > Medial: Mask (face & taste) - Ventro-postero-lateral (VPL): spinothalamic tract and medial lemniscus > VPL: Vibration, Pain, Pressure, Proprioception, Light touch and temperature Efferent: - Brodmann Area 3, 1, 2 (sensory cortex) 18) 🅔 Geniculate bodies
Eye and Ear Lateral geniculate body: Light (eyes) Afferent: optic tract Efferent: calcarine sulcus (area 17) Medial geniculate body: Music (ear) Afferent: superior olive & inferior colliculus Efferent: primary auditory cortex (area 41 & 42)

19) 🅕 Medial dorsal nucleus
Feelings (limbic system) Afferent: amygdala & olfactory cortex Efferent: prefrontal cortex & limbic system

20) 🅖 Pulvinar Gloat (“fix” – control of eye movements) Afferent: pretectal nucleus & superior colliculus Efferent: association cortex
21) 🅗 Reticular nucleus
Halt thalamus Afferent: cortex and interthalamic nuclei * interthalamic connections largely inhibiton Efferent: thalamic nuclei

22) 🅘 Intralaminar nucleus
Intent and arousal in Intralaminar nucleus *alertness Afferent: cortex, brainstem, and spinal cord Efferent: cortex & basal ganglia

23) Relation between
thalamus & internal capsule


24) What are the rings above thalamus?
Caudate nucleus Stria terminalis Lateral ventricle Fornix


25) Caudate nucleus
“It is a rat” Head, body, and tail (amygdaloid body) Cheese – lentiform nucleus Salad – internal capsule Egg – thalamus


 26) Hypothalamus


27) Function

“HEAL” Homeostasis of Endocrine + ANS + Limbic systems

28) Anatomy
- part of the diencephalon - beneath the thalamus ("hypo"thalamus) - posteriorly and dorsally to the optic chiasm

29) Nucleus and lesions


30) Connections
“TSH Master Function to VID” - 12 pathways


31) Mnemonic
“maintains homeostasis by regulating TANHATS” Thirst and water balance Adenohypophysis (anterior pituitary) Neurohypophysis (posterior pituitary) Hunger Autonomic nervous system Temperature Sexual urges
32) Summary figure


33) Subthalamus

34) Function
 “part of the indirect pathway of the basal ganglia”
35) Components
Nuclear FIFA Nuclear: subthalamic nucleus Fasciculus: subthalamic fasciculus Incerta: zona incerta Forel: fields of Forel Ansa: ansa lenticularis