23.3 Hypothalamus Flashcards
What are the neural connections via the large fibre bundles?
Largely reciprocal.
What foetal structure is the hypothalamus derived from?
Diencephalon
How does the hypothalamus relate to the ventricular system?
Forms floor and ventral walls of 3rd ventricle.
Draw the position of the hypothalamus in the brain.
What are the main parts of the hypothalamus?
- Anterior -> Divided into the chiasmatic and tuberal
- Posterior
What are the main nuclei of the hypothalamus that you need to know?
- Suprachiasmatic nucleus
- Anterior hypothalamus
- Posterior hypothalamic area
- Supraoptic/paraventricular nucleus
- Median eminence/arcuate nucleus/paraventricular nucleus
- Ventromedial nucleus
- Lateral hypothalamus
- Mammillary body
Label the hypothalamic nuclei.
Label the hypothalamic nuclei.
Summarise the physiological functions of the hypothalamus.
- Maintaining internal environment:
- Temperature control
- Reproductive functions
- Biological clock
- Control of blood flow
- Behaviour
- Memory
What are the two ways in which the hypothalamus can carry out its functions?
- Regulation of the autonomic nervous system
- Release of hormones (neuro-endocrine)
What things does the hypothalamus detect and how?
- 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).
What does the hypothalamus receive input from?
[IMPORTANT]
- Sensory systems
- Retina
- Olfactory system
- Cutaneous receptors
- Visceral receptors
- Higher centres
- Hippocampal formation
- Amygdala
- Orbitofrontal cortex
- Brainstem nuclei
- Locus coeruleus
- Raphe
- Periaqueductal grey
Via what does the hypothalamus receive visceral sensory input?
[IMPORTANT]
Reticular formation and solitary tract
What parts of the brainstem does the hypothalamus receive input from?
[IMPORTANT]
- Raphe nucleus
- Periaqueductal grey
- Locus coerulus
Via what does the hypothalamus receive input from the orbitofrontal cortex?
[IMPORTANT]
Mediodorsal thalamus
What does the hypothalamus output to?
[IMPORTANT]
- Thalamus
- Anterior pituitary (via portal stream)
- Posterior pituitary (just passing through)
- Brainstem parts:
- Amygdala
- Periaqueductal grey
- Others
What are the main large fibre bundles that connect the hypothalamus? Where do they go?
[IMPORTANT]
- 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
Fornix Function
Carries information from the hippocampus to the mammillary bodies of the hypothalamus.
(Shown in red)
Function
Stria terminalis
Carries information from amygdala to the hypothalamus, thalamus nucleus accumbens (in forebrain) and septal nuclei of the forebrain.
(Shown in green)
Function?
Medial forebrain
Carries information from the anterior nuclei of the hypothalamus to the midbrain, and vice versa.
(Shown in blue)
Function
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)
Label these bundles.
From which higher centres does the hypothalamus receive input?
*Hippocampal formation, amygdala, orbitofrontal cortex
What is the function of the Suprachiasmatic nucleus
biological clock, input from light-sensitive
retinal ganglion cells
What is the function of the Anterior hypothalamus. What is it involved in?
thermoregulation
Fever
What is the function of the Posterior hypothalamic area? is it para/sympathetic?
fear and aggression.
Sympathetic
What is the function of the Median eminence/arcuate nucleus/paraventricular nucleus?
control of
appetite, metabolic rate, anterior pituitary
What is the function of the Ventromedial nucleus
satiety ‘centre’
What is the function of the Lateral hypothalamus
(hunger ‘centre’
What is the function of the Mammillary body. What disease is it associated with?
memory.
Korsakov syndrome
What is the function of the subfornical organ>
Thirst, osmoreception.
Describe the blood supply to the hypothalamus and pituitary.
- From the internal carotid artery
- There is a capillary plexus in the median eminence
What are the efferents of the hypothalamus?
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
What are the autonomic connections dealing witht the hypothalamus (2)?
What arteries supply the posterior pituitary gland?
Direct supply from the inferior hypophyseal arteries
What is the significance of the superior hypophyseal artery in hypothalamic-hypophyseal tract?
The superior hypophyseal arteries supply both the hypothalamus, medium eminence and portal vessels so they link the two structures together
What are the branches of the superior hypophyseal arteries?
Portal veins which pass to the anterior pituitary carrying releasing factors which act on the anterior pituitary gland
Which arteries supply the primary capillary plexus in the median eminence and hypothalamus?
Superior hypophyseal arteries
What is the main blood vessel which supplies the hypothalamus and pituitary?
Internal carotid artery
Where is the hypothalamus located?
Subcortical region of the brain on the ventral surface of the thalamus
What type of responses are controlled by the hypothalamus?
Autonomic (head ganglion of the autonomic nervous system)
Endocrine (hormonal output via pituitary gland)
IMPORTANT FOR HOMEOSTASIS
Describe the general anatomy of the hypothalamus in relation to other structures
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)
Which hypothalamic areas generally regulate autonomic responses?
Posterior and anterior hypothalamic areas
What separates the hypothalamus from the thalamus?
Hypothalamic sulcus (runs from tip of the fornix to posterior commissure)
Outline the autonomic functions of the hypothalamus? Where do these functions occur?
Increasing sympathetic drive (posterior hypothalamic area)
Decreasing body temperature (anterior hypothalamic area)
Promoting fever (anterior hypothalamic area)
Outline four major limbic connections to the hypothalamus. By which pathways (red)?
