The diencephalon

Question 1

What are the subdivisions of the diencephalon

Answer 1

Epithalamus
Thalamus
Hypothalamus

Question 2

Describe the epithalamus

Answer 2

• Is the most dorsal portion of the diencephalon
• Contains some small nuclei and their connections
• Contains the pineal gland

Question 3

What is the function of the pineal gland

Answer 3

produces melatonin and plays a role in circadian and seasonal rhythms

Question 4

Describe the location of the thalamus

Answer 4

is found on either side of the dorsal portion of the 3rd ventricle- is connected by the interthalmic adhesion

Question 5

Describe the location of the hypothalamus

Answer 5

• Lies below the thalamus

- Exposed on the ventral or basal surface of the brain

Question 6

What is the general function of the thalamus

Answer 6

serves as a relay station for information destined for higher centres e.g. cerebral cortex

Question 7

How do fibres access the cerebral hemisphere from the diencephalon

Answer 7

via internal capsules

Question 8

List the key functions of the epithalamus

Answer 8

• key for circadian rhythm
• connect limbic system to other parts of brain
• causes secretion from pineal gland
• Regulate motor pathways and emotion

Question 9

How does the interthalamic adhesion form

Answer 9

Right and left thalami may project medially and meet together forming the interthalamic adhesion

Question 10

Give details on the location of different sensory nuclei through the thalamus

Answer 10

• General and special sensory information relays through appropriate groups of thalamic nuclei:
• General through ventral group
• Special through geniculate nuclei
• Impulses then pass via the internal capsules and visual and auditory radiations to reach appropriate cortical sensory areas

Question 11

How does special nuclei differ in thalamus

Answer 11

Have well-defined sensory and motor functions

Have highly organized point to point connection with sensory and motor regions of cerebral cortex

Question 12

How does non-special nuclei differ in thalamus

Answer 12

Receive less functionally distinct afferent input

Connect with wider area of cortex, including associative and limbic regions

Question 13

Name the three main specific nuclei in the thalamus

Answer 13

• Lateral geniculate nucleus
  Medial geniculate nucleus
  Ventrolateral

Question 14

Describe the lateral geniculate nucleus of the thalamus

Answer 14

runs from eye to primary visual cortex

Question 15

Describe the medial geniculate nucleus of the thalamus

Answer 15

run from the inner ear to primary auditory cortex

Question 16

Describe the ventrolateral nuclei in the thalamus

Answer 16

run from the cerebellum to primary motor cortex

Question 17

What is the internal capsule

Answer 17

Embeds thalamus

Question 18

When would impulses not go via the thalamus when sent to brain

Answer 18

Some impulses are directly sent to colliculi to the midbrain (mesencephalon)

Question 19

Give the difference between information sent to the thalamus and the hypothalamus

Answer 19

That information sent to thalamus is conscious

Information being sent to the hypothalamus is not conscious