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Flashcards in Diencephalon Deck (21)
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Diencephalon

Thalamus
Hypothalamus
Epithalamus

Develops from prosencephalon

Sensory and motor processing. .

Extends from brain stem to cerebrum, surrounds 3rd ventricle.

1

Thalamus

In diencephalon

Paired oval masses of grey matter organized in nuclei with interspersed tracts of white matter.

Relays almost all sensory input to cerebral cortex.

Also involved in motor function and maintenance of consciousness

2

Intermediate mass

Inter thalamus adhesion

Bridge of grey matter the joins right and left hemispheres of thalamus

(In about 70% of population)

3

Intermedullary lamina

Divides grey matter in each half of the thalamus.

Axons entering and leaving thalamus nuclei.

4

Internal capsule

Thick band of white matter in lateral thalamus

Axons connecting thalamus to cerebral cortex pass through.

5

Ventral posterior nucleus

Thalamus
Relays impulses for somatic sensations like touch, pressure, vibration, itch, tickle, temperature, pain, proprioception

7

Lateral geniculate nucleus

Thalamus
Relays visual impulses for sight from retina to primary visual area of cerebral cortex.

8

Medial geniculate nucleus

Thalamus
Relays auditory impulses from hearing from ear to primary auditory area of cerebral cortex

9

Hypothalamus

Small part of diencephalon.
Inferior to thalamus.
One of the main regulator of homeostasis
4 regions: mammillary, tuberal, supraoptic, preoptic

10

Mammillary Region

Most posterior region of hypothalamus
Adjacent to midbrain
Contains mammillary bodies (relay stations for reflexes associated with smell) and posterior hypothalamic nuclei

11

Tuberal Region

Widest portion of hypothalamus.
Contains dorsomedial, ventromedial, and arcuate nuclei.
Also contains infundibulum and median eminence.

12

Infundibulum

Tuberal region.
Connects pituitary gland to hypothalamus
Encircled by median eminence

13

Supraoptic Region

Hypothalamus.
Superior to optic chiasm.
Contains paraventricular, supraoptic, anterior hypothalamic and suprachiasmatic nuclei

14

Suprachiasmatic nucleus

In supraoptic region of the hypothalamus.
Involved in circadian rhythm.

15

Preoptic region

Hypothalamus; anterior to supraoptic region.
Regulates some autonomic areas
Contains medial and lateral preoptic nuclei

16

Functions of Hypothalamus

Control of ANS
Production of hormones
Regulates emotional and behavioural patterns
Regulates eating and drinking (feeding, satiety, thirst)
Control of body temperature
Regulates circadian rhythm

17

Hypothalamus: role in hormone production

Cooperates with pituitary gland.
1. Release releasing and inhibiting hormones that act on anterior pituitary hormones.
2. Axons from paraventricular and supraoptic nuclei act on posterior pituitary (through infundibulum) to release oxytocin and antidiuretic hormone (vasopressin).

18

Epithalamus

Pineal gland + habenular nuclei

19

Pineal gland

Secretes melatonin

20

Habenular nuclei

Involved in olfaction, especially emotional response to olfactory stimulation

21

Circumventricular Organs (CVO)

Diencephalon
In wall of third ventricle.
Monitor chemical changes (no blood brain barrier)
Include part of the hypothalamus, the pineal gland, the pituitary gland etc.
Coordinate homeostatic activities of endocrine and nervous systems (BP, fluid balance, hunger, thirst)