3. 1. Introduction
⢠The most ventral part of
diencephalon which lies
below the thalamus
⢠4 gram in weight (whole
brain wt 1400gms)
⢠0.3 to 0.5% of total brain
⢠Sherrington regarded as
head ganglion of ANS
⢠Nauta describes as the
nodal region in the
maintenance of homeostais4/18/2014 3
11. 6. Region wise descriptions of Nuclei
A. Preoptic Region:
Lies anterior to
hypothalamus
along with
lamina terminalis
between optic
chiasma &
ant.commissure
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12. B. Supra optic Region:
1. Supra optic Nucleus: Medail,
lateral and periventricular
part. It is Sexually dimorphic
Nuclei.
2. Suprachiasmatic: Involves
circadian rhythm
3. Anterior Nucleus: Thirst
Center
4. Paraventricular
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13. C. Tuberal Region
1. Arcuate or infundibular
nucleus: composed of
small neurons.
Controls emontional
behaviours and
endocrine function
2. Ventromedial: Satiety
centre
3. Ventrolateral
4. Lateral nucleus: feedin
centre
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14. D. Mamillary Region
1. Mamillary bodies:
i) Medial intercalated N.:
small neurons. Forms
the bulk of mamillary
bodies.
ii) Lateral intercalated N.:
Receive termination of
fornix and provide origin
to mamilothalamic tract
and mamilotegmental
tract
1. Posterior hypothalamic
nucleus
4/18/2014 14
26. Functions: 1. Controls posterior pitutary
⢠It controls neurohypophysis
through hypothalamo-
hypophyseal tract.
⢠Approx. 100,000
nonmyelinated fibers
extend from the SON & PVN
of the hypothalamus to the
fenestrated capilary bed of
the neurohupophysis.
⢠These fibers convey 2
peptide hormones; ADH &
oxytocin
4/18/2014 26
27. 2. Controls anterior pitutary
⢠Several trophic factors or
hormones are released
that influence the
production of hormones in
adenohypophysis.
4/18/2014 27
32. Neuro-secretory cells
1. Receive and process stimuli from
all parts of the CNS,
2. Conduct action potentials along
their axons, and
3. Synthesize and release hormones
into the circulatory system.
4. produce peptide prohormones by mRNA
on ribosomes in their nerve cell bodies,
and then convert these prohormones to
active hormones during the process of
axoplasmic transport along axon
filaments.
5. They store the hormones in vesicular
granules at their axon terminals until
depolarization of the plasma membrane
causes exocytosis.
4/18/2014 32
33. 3. Autonomic regulation
⢠It controls brain stem & spinal cord autonomic
centers.
⢠Autonomic influence is mediated by dorsal
longitudinal fasciculus & mamilothalamic tract
⢠Rostral & medial hypothalamus is concerned
with parasympathetic control
⢠Caudal & lateral hypothalamus is concerned with
sympathetic control mechanism.
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34. 4. Temperature regulation
⢠contains thermal recepters which is sensetive to
changes in the body temperature of blood
perfusing these regions.
⢠Anterior regions of hypothalamus is are sensetive
to rise in blood temperature.
⢠B/L damage to this regions results hyperthermia
4/18/2014 34
35. 5. Emotional behavior
⢠Ventromedial nucleus of hypothalamus is
related to emotional behavior.
6. Feeding Behavior:
Ventro medial NucleusâŚfeeding centre
Dorsomedial nucleusâŚ.satiety centre
Anterior & lateral regionâŚthirst centre
4/18/2014 35
36. 7. Sleep & awakefulness
⢠Anterior part of hypothalamusâŚ.sleep centre
⢠Posterior⌠waking centre
8. Biological clock or circadian Rhythm:
⢠Through the connections of the suprachiasmatic nucleus
with the retina and brain, it reghulates the circadian
rhythm loke sleep-wake cycle, hormonal cycle etc.
⢠So suprachiasmatic nucleus is also refered as
endogenous pacemaker
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37. 9. Memory
⢠Through its connections with the hippocampal
formation & anterior thalamic nucleus, the
mamillary body of hypothalamus plays a role in
memory
10. Sexual arousal:
⢠Medial preoptic nucleus is concerned with the
sexual arousal to erotic stimuli.
⢠It size is double in case of male than in female.
⢠So it is also refered as sexually dimerfic nucleus
4/18/2014 37
38. Blood supply
Perforating brach of
1. Anterior communicating
artery & anterior cerebral
arteryâŚ.
i) Preoptic & supraoptic region
ii) Rostral part of lateral
hypothalamus
2. posterior communicating artery
& posterior cerebral arteryâŚ.
i) Tuberal & mamillary regions
ii) Middle & posterior part of
lateral hypothalamus
4/18/2014 38
41. Clinical Anatomy
1. Disorder of water balance
A. Diabetes inspidius
⢠It results due to lesions that destroy the majority of the
neurons of SON & PVN.
⢠Or due to interuption of the hypothalamo-hypophusial
tract
⢠Decreased ADH results polyurea
B. SIADH ( Syndrome of inappropriate secretion of ADH)
Due to lesions in SON & PVN that impair hypothalamic
osmoreceptors resulting increased ADH release.
So concentrated urine is excreted
4/18/2014 41
42. 2. Disorders of Thermoreghulation
i) Hypothermia: posterior pituitary lesion
ii) Hyperthermis: related to lesion of ventomedial
nucleus
iii) Poikilothermia: fluctuation of body
temperature. It is due to B/L posterior
hypothalamic lesion
4/18/2014 42
43. 3. Disorders of caloric balance
i) Diencephalic syndrome of infancy or
Russell syndrome or
Batten- Russel- Collier Disease
⢠It is characterised by progressive emanciation during the first
year of life despite of a reasonable food intake
⢠It is due to slowly growing tumor affecting the hypothalamus
⢠Other lesion of anterior nucleus can produce the syndrome.
ii) Frohlich syndrome or Babinski-Frohlich syndrome or
Dystrophia âAdiposogenitalis
⢠ObesityâŚ.due to lesion of ventrolateral nucleus ( satiety center)
⢠Genital hypoplasia⌠due to involvement of infundibulum
⢠Stunted growth4/18/2014 43
44. 4. Disorders of emotional behavior
⢠Ventromedial nucleus lesion have been
associated with Rage
⢠Posterior nucleus lesion is related to fear and
apathy
⢠Stimulation of lateral region of anterior nucleus
elicits flight response
4/18/2014 44
45. 5. Disorders of sleep
⢠Waking centre is in posterior nucleus. So lesion
on it produce lethargy and hypersomnia.
⢠Sleep centre is in anterior nucleus. So lesion on
it produces insomnia.
4/18/2014 45
46. 6. kleine-Levin Syndrome
It is characterised by
⢠Episodic compulsive eating
(bulimia)âŚâŚ..predominently seen in females
⢠Hypersomnolence
⢠Hypersexuality⌠predominently seen in adult males
It is due to lesion of medial nucleus of
hypothalamus
4/18/2014 46
47. 7. Disorders of Memory
⢠Lesion of posterior nucleus are associated with
inability to memorise the recent event.
⢠Connections of mamillary body with
hippocampus vai fornix and with anterior
nucleus of thalamus via mamillothalamic tract
is interrupted.
4/18/2014 47
