23.3 Hypothalamus

Question 1

What are the neural connections via the large fibre bundles?

Answer 1

Largely reciprocal.

Question 2

What foetal structure is the hypothalamus derived from?

Answer 2

Diencephalon

Question 3

How does the hypothalamus relate to the ventricular system?

Answer 3

Forms floor and ventral walls of 3rd ventricle.

Question 4

Draw the position of the hypothalamus in the brain.

Answer 4

Question 5

What are the main parts of the hypothalamus?

Answer 5

• Anterior -> Divided into the chiasmatic and tuberal
• Posterior

Question 6

What are the main nuclei of the hypothalamus that you need to know?

Answer 6

• Suprachiasmatic nucleus
• Anterior hypothalamus
• Posterior hypothalamic area
• Supraoptic/paraventricular nucleus
• Median eminence/arcuate nucleus/paraventricular nucleus
• Ventromedial nucleus
• Lateral hypothalamus
• Mammillary body

Question 7

Label the hypothalamic nuclei.

Answer 7

Question 8

Label the hypothalamic nuclei.

Answer 8

Question 9

Summarise the physiological functions of the hypothalamus.

Answer 9

• Maintaining internal environment:
  
  • Temperature control
  • Reproductive functions
  • Biological clock
  • Control of blood flow
• Behaviour
• Memory

Question 10

What are the two ways in which the hypothalamus can carry out its functions?

Answer 10

• Regulation of the autonomic nervous system
• Release of hormones (neuro-endocrine)

Question 11

What things does the hypothalamus detect and how?

Answer 11

• Blood osmolarity
• Blood nutrient levels
• Blood hormone levels
• Blood temperature

It detects this directly (using neurons that are sensitive to these things) and indirectly (using input from peripheral receptors and other parts of the brain that are sensitive to these factors).

Question 12

What does the hypothalamus receive input from?

[IMPORTANT]

Answer 12

• Sensory systems
  
  • Retina
  • Olfactory system
  • Cutaneous receptors
  • Visceral receptors
• Higher centres
  
  • Hippocampal formation
  • Amygdala
  • Orbitofrontal cortex
• Brainstem nuclei
  
  • Locus coeruleus
  • Raphe
  • Periaqueductal grey

Question 13

Via what does the hypothalamus receive visceral sensory input?

[IMPORTANT]

Answer 13

Reticular formation and solitary tract

Question 14

What parts of the brainstem does the hypothalamus receive input from?

[IMPORTANT]

Answer 14

• Raphe nucleus
• Periaqueductal grey
• Locus coerulus

Question 15

Via what does the hypothalamus receive input from the orbitofrontal cortex?

[IMPORTANT]

Answer 15

Mediodorsal thalamus

Question 16

What does the hypothalamus output to?

[IMPORTANT]

Answer 16

• Thalamus
• Anterior pituitary (via portal stream)
• Posterior pituitary (just passing through)
• Brainstem parts:
  
  • Amygdala
  • Periaqueductal grey
• Others

Question 17

What are the main large fibre bundles that connect the hypothalamus? Where do they go?

[IMPORTANT]

Answer 17

• Fornix -> From the hippocampus to the mammillary bodies
• Stria terminalis -> From amygdala to the medial thalamus
• Mammillothalamic tract -> From the mammillary bodies to the dorsal tegmental nuclei, the ventral tegmental nuclei, and the anterior thalamic nuclei
• Medial forebrain bundle -> From anterior nuclei to the midbrain, and vice versa

Question 18

Fornix Function

Answer 18

Carries information from the hippocampus to the mammillary bodies of the hypothalamus.

(Shown in red)

Question 19

Function

Answer 19

Stria terminalis
Carries information from amygdala to the hypothalamus, thalamus nucleus accumbens (in forebrain) and septal nuclei of the forebrain.

(Shown in green)

Question 20

Function?

Answer 20

Medial forebrain
Carries information from the anterior nuclei of the hypothalamus to the midbrain, and vice versa.

(Shown in blue)

Question 21

Function

Answer 21

mammillothalamic tract
Carries information from the mammillary bodies to the dorsal tegmental nuclei, the ventral tegmental nuclei, and the anterior thalamic nuclei.

(Shown in red)

Question 22

Label these bundles.

Answer 22

Question 23

From which higher centres does the hypothalamus receive input?

Answer 23

*Hippocampal formation, amygdala, orbitofrontal cortex

Question 24

What is the function of the Suprachiasmatic nucleus

Answer 24

biological clock, input from light-sensitive
retinal ganglion cells

Question 25

What is the function of the Anterior hypothalamus. What is it involved in?

Answer 25

thermoregulation Fever

Question 26

What is the function of the Posterior hypothalamic area? is it para/sympathetic?

Answer 26

fear and aggression. Sympathetic

Question 27

What is the function of the Median eminence/arcuate nucleus/paraventricular nucleus?

Answer 27

control of appetite, metabolic rate, anterior pituitary

Question 28

What is the function of the Ventromedial nucleus

Answer 28

satiety ‘centre’

Question 29

What is the function of the Lateral hypothalamus

Answer 29

(hunger ‘centre’

Question 30

What is the function of the Mammillary body. What disease is it associated with?

Answer 30

memory. Korsakov syndrome

Question 31

What is the function of the subfornical organ>

Answer 31

Thirst, osmoreception.

Question 32

Describe the blood supply to the hypothalamus and pituitary.

Answer 32

* From the internal carotid artery * There is a capillary plexus in the median eminence

Question 33

What are the efferents of the hypothalamus?

Answer 33

Endocrine: Posterior piuitary (ADH and oxytocin) Anterior pituitary (pituitary releasing hormones) Autonomic control: Brainstem Edinger-Westphal (III) Vagal motor nucleus Superior cervical ganglion (pineal gland) Sympathetic preganglionic neurons (anterior hypothalamic nucleus) Parasympathetic preganglionic neurons (posterior hypothalamic nucleus) Mammillothalamic tract

Question 34

What are the autonomic connections dealing witht the hypothalamus (2)?

Answer 34

Question 35

What arteries supply the posterior pituitary gland?

Answer 35

Direct supply from the inferior hypophyseal arteries

Question 36

What is the significance of the superior hypophyseal artery in hypothalamic-hypophyseal tract?

Answer 36

The superior hypophyseal arteries supply both the hypothalamus, medium eminence and portal vessels so they link the two structures together

Question 37

What are the branches of the superior hypophyseal arteries?

Answer 37

Portal veins which pass to the anterior pituitary carrying releasing factors which act on the anterior pituitary gland

Question 38

Which arteries supply the primary capillary plexus in the median eminence and hypothalamus?

Answer 38

Superior hypophyseal arteries

Question 39

What is the main blood vessel which supplies the hypothalamus and pituitary?

Answer 39

Internal carotid artery

Question 40

Where is the hypothalamus located?

Answer 40

Subcortical region of the brain on the ventral surface of the thalamus

Question 41

What type of responses are controlled by the hypothalamus?

Answer 41

Autonomic (head ganglion of the autonomic nervous system) Endocrine (hormonal output via pituitary gland) IMPORTANT FOR HOMEOSTASIS

Question 42

Describe the general anatomy of the hypothalamus in relation to other structures

Answer 42

Bilateral mass of grey matter below the thalamus Lies either side of and floors the third ventricle Lies under the hypothalamic sulcus (divides left and right walls of the third ventricle)

Question 43

Which hypothalamic areas generally regulate autonomic responses?

Answer 43

Posterior and anterior hypothalamic areas

Question 44

What separates the hypothalamus from the thalamus?

Answer 44

Hypothalamic sulcus (runs from tip of the fornix to posterior commissure)

Question 45

Outline the autonomic functions of the hypothalamus? Where do these functions occur?

Answer 45

Increasing sympathetic drive (posterior hypothalamic area) Decreasing body temperature (anterior hypothalamic area) Promoting fever (anterior hypothalamic area)

Question 46

Outline four major limbic connections to the hypothalamus. By which pathways (red)?

Answer 46