Gross anatomy and connections of hypothalamus

1. 4/18/2014 1

2. Hypothalamus
Presenter: Dr. Kapil Amgain
Chairperson: Prof. Dr. S.P. Desai
4/18/2014 2

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

4. 2. Boundaries
4/18/2014 4

5. 3. Relations
• Anteriorly: LaminaTerminalis
• Laterally: Internal Capsule &
ventral thalmus
• Medially: ependymal lining
of 3rd ventricle
• Posteriorly: Ventral thalamus
via tegmentum of midbrain
• Superiorly: Dorsal Thalamus
4/18/2014 5

6. Inferior Relation
4/18/2014 6

7. 4/18/2014 7
4.

8. 4/18/2014 8
5.

9. 4/18/2014 9

10. 4/18/2014 10

11. 6. Region wise descriptions of Nuclei
A. Preoptic Region:
Lies anterior to
hypothalamus
along with
lamina terminalis
between optic
chiasma &
ant.commissure
4/18/2014 11

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
4/18/2014 12

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
4/18/2014 13

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

15. 4/18/2014 15

16. 4/18/2014 16

17. Afferent Connections
S.N. Afferent Tracts Origin Termination
1. Retinothalamic Ganglion cells of Retina Suprachiasmatic Nucleus
2. Inferior
mamillary
peduncle
Tegmentl nuclei of midbrain Mamillary
3. Thalamo-
hypothalamic
Dorsomedial & midline
thalamic nuclei
Lateral & posterior
hypothalamus
4 Pallidohypothala
mic
Lentiform nucleus Ventromedial hypothalamic
nuclei
5 Cerebello-
hypothalamic
Deep nuclei of cerebellum Ventral & posterior nuclei of
hypothalamus
6 Prefrontal
hypothalamic
Orbitofrontal cortex, medial
frontal cortex
Prefrontal cortex
4/18/2014 17

18. Efferent Connections
S.N. Afferent Tracts Origin Termination
1 Hypothalamo-
hypophysial tract
Supraoptic & paraventricular
Nuclei
Neurohypophysis
2 Tuberohypophysial
tract
Arcuate & periventricular Median eminence &
infundibular stalk
3 Hypothalamo-
cerebellar fibers
Laterar & posterior hypothalamus Deep cerebellar
cortex
4 Mamillothalamic
fibers
Mamillary body Anterior thalamic
nucleus
5 Mamillotegmental
fibers
Mamillary body Tegmental nuclei of
midbrain
6 Descending
autonomic fibers
Paraventricular nucleus,lateral
hypothalamic area, postrior
hypothalamus
Autonomic cranial
nerve nuclei &
spinal cord nuclei
7 Hypothalamic
prefrontal
Posterior hypothalamus, Tuberal
hypothalamus, Anterior
hypothalamus
Prefrontal cortex
4/18/2014 18

19. Both Afferent & efferent connections
S.N. Pathways Origin Termination
1 Stria Terminalis Amygdaloid nucleus.
Preoptic & arcuate nuclei
Preoptic &arcus nuclei.
Amygdaloid nucleus
2 Fornix Hippocampal formation.
Mamillary body
Mamillary body.
Hippocampal formation
3 Ventral amygdalofugal
fibers
Amygdaloid nucleus.
Lateral hypothalamic
nucleus
Lateral hypothalamic
nucleus.
Amygdaloid nucleus
4 Medial forebrain
bundle
Amygdala, premotor
cortex,frontal cortex.
Lateral hypothalamus
Lateral hypothalamus.
Septal nuclei, tegmental
nuclei, periaquductal gray
matter of midbrain
5 Dorsal longitudinal
fasciculus of schutz
periaquductal gray matter
of midbrain.
Medial hypothalamus
Medial hypothalamus.
periaquductal gray matter of
midbrain.
4/18/2014 19

20. Major connections
4/18/2014 20

21. 4/18/2014 21

22. Hypothalamo-hypophysial tract
• The
hypothalamus
is a
neuroendocrine
area which acts
as a
"transducer" to
convert
neuronal
activity into
hormonal
secretions
4/18/2014 22

23. Hypothalamus and Anterior Pitutary
• GHRH
• FSHRH
• LHRH
• GnRH
4/18/2014 23

24. 4/18/2014 24

25. 4/18/2014 25

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

28. 4/18/2014 28

29. Hormones Released
4/18/2014 29

31. 4/18/2014 31

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.
4/18/2014 33

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 Nucleus…feeding centre
Dorsomedial nucleus….satiety centre
Anterior & lateral region…thirst centre
4/18/2014 35

36. 7. Sleep & awakefulness
• Anterior part of hypothalamus….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
4/18/2014 36

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
artery….
i) Preoptic & supraoptic region
ii) Rostral part of lateral
hypothalamus
2. posterior communicating artery
& posterior cerebral artery….
i) Tuberal & mamillary regions
ii) Middle & posterior part of
lateral hypothalamus
4/18/2014 38

39. 4/18/2014 39

40. Circumventricular Organs
4/18/2014 40

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 –Adiposogenitalis
• Obesity….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)……..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

48. 4/18/2014 48