Anatomy, physiology and Functions of thalamus and hypothalamus

1. Thalamus and Hypothalamus
Presented by-
Dr. Farhad Uddin Ahmed
Dr. Hosney Jahan
Dr. Md. Mahfuzul Alam
Resident, Ophthalmology, NIO.

2. Thalamus
Presented by-
Dr. Farhad Uddin Ahmed
Resident (Phase-A)
Ophthalmology

3. Introduction
• Thalamus derives from a latin word that means “Inner Chamber” or
“meeting Place”
• It is situated at the rostral end of brainstem
• Major part of diencephalon
• Paired, egg shaped mass of gray matter
• Important relay and integrative station for information

4. Relations of Thalamus
• Superior surface-
Stratum zonale
Body of Fornix
• Inferior surface-
Subthalamus
Tegmentum of midbrain

5. Relations of Thalamus
• Medial Surface-
lateral wall of 3rd ventricle
Interthalamic adhesion
• Lateral Surface-
External medullary lamina
Reticular nucleus

6. Internal Structure of Thalamus
• The gray matter of the thalamus is divided by a “Y” shaped vertical
sheet of white matter called the internal medullary lamina.
• It divides the thalamus into three part-
Anterior part
Medial part
Lateral part

8. Classification of thalamic Nuclei
• Neuroanatomic classification
-Anterior group of nuclei
-Medial group of nuclei
-Lateral group of nuclei

10. Connections of thalamus
• Every thalamic nucleus (except the reticular nucleus) sends axons to
specific parts of the cerebral cortex and every part of the cerebral cortex
sends reciprocal fibres back to the thalamic nuclei.
• Information received by the thalamus is always shared with the cerebral
cortex and that the cortex and thalamus can modify each other's
activities.
• Thalamus is an important relay station for two sensory motor axonal
loops involving the cerebellum and basal nuclei
1. Cerebellar- rubro- thalamic - cortical - ponto – cerebellar – loop
2. Corticostriatal – pallidal – thalamic – cortical loop
Both are necessary for normal voluntary movement.

11. Connections

12. Anterior group:
Anterior thalamic nuclei
Afferent-
 Mammillary body
 Cingulate gyrus
 Hypothalamus
Efferent-
 Cingulate gyrus
Function-
 Recent memory
 Emotional tone

13. Medial group:
Dorsomedial Nucleus
Afferent-
 Prefrontal cortex
 Other thalamic nuclei
 Hypothalamus
Efferent-
 Prefrontal cortex (area 8, 9,10
,11 and 12)
Function-
 Integration of somatic,
visceral and olfactory
information
 Relation to emotional feelings
and subjective states.

14. Lateral group: Ventral tier
Ventral Anterior Nucleus
Afferent-
 substantia nigra,
 corpus striatum,
 reticular formation,
 intralaminar thalamic nuclei,
 premotor and prefrontal cortices (areas 6 and 8).
Efferent-
 Reticular formation,
 Premotor cortex,
 Substantia nigra,
 Corpus striatum,
 other thalamic nuclei
Function-
Influences motor activity of motor cortex

15. Ventral Lateral Nucleus
Afferent-
 As in ventral anterior nucleus
 Major input from cerebellum
Efferent-
 As in ventral anterior nucleus
 Major output from red nucleus
Function-
Influences motor activity of
motor cortex

16. Ventral Posterior Nucleus
subdivided in to
1. Posteromedial nucleus
2. Posterolateral nucleus
Afferent-
 Ascending trigeminal and gustatory pathway
 Ascending sensory tracts
 Medial and lateral lamnisci
Efferent-
 Primary somatic sensory (areas 3, 1, and 2 in post
central gyrus) cortex via posterior limb of internal
capsule.
Function-
• Relay sensory impulse from face and taste (VPM)
• Relay somatosensory impulse (touch pressure ,
pain, proprioception, temperature and
kinesthetic) from trunk and limb(VPL)

17. Dorsal tier:
Lateral dorsal, lateral posterior and Pulvinar
Nucleus
• Afferent-
 Cerebral cortex
 Other thalamic nucleus
• Efferent-
 Cerebral cortex
 Other thalamic nucleus
• Function-
 Correlates visual & auditory information with other sensations

18. Others nucleus
Intra laminar Nuclei
Within the internal medullary lamina
Afferent-
 Reticular formation
 Spinothalamic and
 trigeminothalamic tracts
Efferent-
 Cerebral cortex
 Corpus striatum
Function-
 Influences levels of consciousness and
alertness

19. Midline nuclei
Adjacent to the 3rd ventricle & in the interthalamic connection
• Afferent
 Reticular formation
 Hypothalamous
 Midbrain
• Efferent
 Hyppocampal formation
 Amygdala
 Cingulate gyrus
Function
Part of limbic system, memory and arousal

20. Reticular Nucleus
Between external medullary lamina and posterior limb of internal
capsule
• Afferent-
Cerebral cortex, reticular formation
• Efferent-
Other thalamic Nuclei
• Function-
Regulations of inter- thalamic activity

21. Medial geniculate nucleus
• Afferent-
Inferior colliculus, lateral lemniscus from both ears but
predominantly the contralateral ear
• Efferent-
The auditory radiation of the internal capsule to the primary
auditory cortex in temporal lobe (areas 41 and 42)
• Function-
Hearing

22. Lateral geniculate nucleus
• Afferent-
Optic tract
• Efferent-
Optic radiation to visual cortex of occipital lobe (area-17)
• Function-
Vision

24. Blood Supply of Thalamus
• Blood supply of the thalamus is derived from four parent vessels: basilar
root of the posterior cerebral, posterior cerebral, posterior communicating,
and internal carotid.
• The basilar root of the posterior cerebral artery, via paramedian branches,
supplies the medial thalamic territory.
• The posterior cerebral artery, via its geniculothalamic branch, supplies the
posterolateral thalamic territory.
• The posterior communicating artery, via the tuberothalamic branch,
supplies the anterolateral thalamic territory.
• The internal carotid artery, via its anterior choroidal branch, supplies the
lateral thalamic territory.

26. Reference-
Snell Clinical Neuroanatomy 8th ed.

27. Anatomy and connection of
hypothalamus
Presented by Dr. Hosney Jahan
Phase- A, Ophthalmology

28. Introduction
• Part of Diencephalone which lies below the thalamus.
• Forms the floor and lower parts of the lateral walls of the 3rd
ventricle.
• Small in size weighing only 4 gm, forms only 0.3% of total brain mass.
• Mainly acts through 3 systems – autonomic nervous system,
endocrine system and limbic system.

30. Boundaries
• Anteriorly – Lamina terminalis, extends from the optic chiasma to the
anterior commissure.
• Posteriorly – Subthalamus.
• Inferiorly – Structures in the floor of the 3rd ventricle (i.e. tuber
cinereum, infundibulum and mamillary bodies).
• Superiorly – Thalamus.
• Laterally - Internal capsule.
• Medially – Bounded by the cavity of 3rd ventricle.

32. Antero-Posteriorly Divided Into
• Preoptic region – area adjoining the lamina terminalis.
• Supra optic region – above the optic chiasma.
• Tuberal region – includes the tuber cinereum, infundibulum and area
around it.
• Mammillary region – includes the mammillary bodies and area
around it.

33. Hypothalamic Nuclei
• Hypothalamus is made up of numerous small nuclear masses
called hypothalamic nucleus.
• They are divided into medial and lateral zones by an
imaginary parasagittal plane between fornix and
mammillothalamic tract.

35. Nuclei

36. Region Nucleus Functions
Preoptic region Preoptic nucleus GnRH release
Supraoptic region Supraoptic nucleus Vasopressin release
Anterior nucleus Thermo regulation, sweating
Paraventricular nucleus TRH, CRH and oxytocin release
Tuberal region Arcuate nucleus GnRH, feeding and Dopamine
release
Ventromedial nucleus Satiety centre
Dorsomedial nucleus Controls BP, HR& GI stimulation

37. Connections of the Hypothalamus
The hypothalamus has afferent and efferent connections with the
rest of the body through :
• Neural connections
 Bloodstream
 Cerebrospinal fluid

38. Afferent Nervous Connections of the
Hypothalamus
• Somatic and visceral afferents.
• General somatic sensation and gustatory and visceral sensations reach the
hypothalamus through collateral branches of the lemniscal afferent fibers and
the tractus solitarius and through the reticular formation
• Visual afferents
• leave the optic chiasma and pass to the suprachiasmatic nucleus
• Olfaction travels through the medial forebrain bundle
• Auditory afferents
• have not been identified, but since auditory stimuli can influence the activities
of the hypothalamus, they must exist.

39. • Corticohypothalamic fibers arise from the frontal lobe of the cerebral cortex
and pass directly to the hypothalamus
• Hippocampohypothalamic fibers pass from the hippocampus through the fornix
to the mammillary body. Many neurophysiologists regard the hypothalamus as
the main output pathway of the limbic system
• Amygdalohypothalamic fibers pass from the amygdaloid complex to the
hypothalamus through the stria terminalis and by a route that passes inferior to
the lentiform nucleus
• Thalamohypothalamic fibers arise from the dorsomedial and midline thalamic
nuclei

41. Efferent Nervous Connections of the
Hypothalamus
• Descending fibers to the brainstem and spinal cord
• Influence the peripheral neurons of the autonomic nervous
system
• They descend through a series of neurons in the reticular
formation
• Connected to the parasympathetic nuclei of the oculomotor,
facial, glossopharyngeal, and vagus nerves in the brainstem

43. •Reticulospinal fibers connect the hypothalamus with
sympathetic cells of origin in the lateral gray horns of the
first thoracic segment to the second lumbar segment of
the spinal cord and the sacral parasympathetic outflow
at the level of the second, third, and fourth sacral
segments of the spinal cord.

44. • The mammillothalamic tract
• Arises in the mammillary body and terminates in the anterior
nucleus of the thalamus
• The pathway is relayed to the cingulate gyrus
• The mammillotegmental tract arises from the mammillary body and
terminates in the cells of the reticular formation in the tegmentum of
the midbrain
• Multiple pathways to the limbic system

46. Hypothalamo-Hypophyseal tract
• Connects hypothalamus to
posterior pituitary.
• Vasopressin and oxytocin are
transported to posterior
pituitary along the fibers of the
tract by axoplasmic flow.

47. Tubero-Infundibular Tract
• The releasing hormones and release
inhibiting hormones are produced in
the cells of tuberal and infundibular
nuclei and are transported upto the
median eminence along the tubero
infundibular tract.
• Releasing hormone – TRH, CRH, GnRH
& LHRH.
• Release inhibitory hormone –
Dopamine & GHIH.

48. References
• Snell Clinical Neuro Anatomy 8th ed.

49. Functions
and
Applied Aspect
By
Dr. Md. Mahfuzul Alam
Resident, Phase A
Ophthalmology

50. 1. Sensory integration: Serves as an important sensory relay station and
integrative center for most inputs to cerebral cortex.
2. Capable of recognition of pain, thermal & tactile sensations
3. Influences voluntary movements.
4. Through ascending activating system – maintains state of wakefulness
and alertness
5. Impulses received from hypothalamus projected to prefrontal &
cingulate gyrus – Determination of mood
6. Recent memory and emotions
Functions of Thalamus

51. The thalamus may be
 invaded by neoplasm
undergo degeneration following
disease of its arterial supply
damaged by hemorrhage
Thalamus applied aspect

52. Bilateral thalamic infarction

53. Thalamic Haemorrhage

54. •Sensory Loss
• Due to Thrombosis or hemorrhage of one of the arteries
supplying the thalamus
• Damage to the VPM and VPL nucleus result in the loss of
all forms of sensation in the opposite side of the body
• Usually, a thalamic lesion results in dysfunction of
neighboring structures
• Lateral extension of thalamic disease may involve the internal
capsule and produce extensive motor and sensory deficits
Effect of lesion of the Thalamus

55. Thalamus ia an important relay station for two sensory – motor axonal
loop involving the cerebellum and basal nuclei
1. Cerebellar-rubro-thalamic-cortical-ponto-cerebellar loop.
2. Corticalstriatal-pallidal-thalamic-cortical loop.
Both loop necessary for normal voluntary movement.
So impairment in any portion of this loop may impaired voluntary
movement.
Effect in lesion in the thalamus

56. Effect of lesion of the Thalamus
Thalamic syndrome
• Caused due to infarct in thalamo-geniculate artery, a branch of
the posterior cerebral artery.
• The clinical hallmark is a pansensory loss which is contralateral
to the lesion, paresthesia, and thalamic pain.
• Transient hemiparesis, hemiataxia, tremor, choreiform
movements, and spatial neglect, all contralateral to the lesion
in the thalamus

57. Effect of lesion of the Thalamus
Thalamic hand
• The contralateral hand is in an abnormal posture in some pateints
with thalamic lesions.
• Pronation and flexion of hand, flexion of MCP joint and extension of
interphalangeal joints.
• The condition is due to altered
muscle tone in the different groups of
muscle .

58. Abnormal Involuntary Movements
oChoreoathetosis with ataxia may follow vascular lesions of
the thalamus
• It is not certain whether these signs in all cases are due to
the loss of function of the thalamus or to involvement of
the neighboring caudate and lentiform nuclei
• The ataxia may arise as the result of the loss of appreciation
of muscle and joint movement caused by a thalamic lesion
Effect of lesion of the Thalamus

59. Bilatteral thalamic lesion: Uncommon
• Causes:
1. Metabolic and toxic process
. Wernicke’s encephalopathy
. Osmotic myelinolysis
. Wilsons disease
. Hypoxic Ischemic Encephalopathy.
2.Viral infectious.
. Japanes B encephalitis
. West neil encephalitis
3.Vascular occlution

60. • Surgical Relief of Pain by Thalamic Cauterization
• The intralaminar nuclei of the thalamus are known to take part in the relay of
pain to the cerebral cortex.
• Cauterization of these nuclei has been shown to relieve severe and
intractable pain associated with terminal cancer.

61. Functions of Hypothalamus

62. ADH
Oxytocin
GH
TSH
ACTH
FSH
LH
Prolactin
Hypothalamus
GHRH
TRH
CRH
GnRH
ADH
Oxytocin
Adenohypophysis Neurohypophysis
Pituitary
Gland
Portal Axoplasmic flow
ENDOCRINE
CONTROL

63. HPT AXIS
• The hypothalamic–pituitary–
thyroid axis is part of
the endocrine system
responsible for the regulation
of metabolism.
HYPOTHALAMUS 63

64. HPA AXIS
• The hypothalamic-pituitary-adrenal
axis (HPA or HTPA axis).
• The interactions among these organs
constitute a major part of
the neuroendocrine system that
controls reactions to stress and
regulates many body processes,
including digestion ,the immune
system, mood and emotions, sexuality
and energy storage and expenditure.
HYPOTHALAMUS 64

65. HPG AXIS
• The hypothalamic–pituitary–
gonadal axis is a critical part in
the development and regulation
of a number of the body's
systems, such as the
reproductive and immune
systems.
• This axis controls development,
reproduction, and aging in
animals.
HYPOTHALAMUS 65

66. Autonomic control of Body
• Hypothalamus has a controlling influence on the
autonomic nervous system.
• Stimulation of anterior hypothalamic area influence
parasympathetic respose.
• Stimulation of posterior hypothalamic area influence
sympathetic respose.

67. Temperature regulation
• The anterior portion of the hypothalamus controls
those mechanisms that dissipate heat loss.
• The posterior portion results in vasoconstriction of
the skin and blood vessels and inhibition of sweating,
there may also be shivering, in which skeletal muscles
produce heat.

68. • Regulation of Food and Water Intake
• Hunger center: lateral region of hypothalamus.
• Satiety center: Medial region
• Thirst center : lateral region
• In addition, supraoptic n. of hypothalamus exert a careful
control on the osmolarity of blood through secretion of ADH.
• Emotion and Behavior
• Emotion and behavior are a function of the hypothalamus,
the limbic system, and the prefrontal cortex.

69. Control of Circadian Rhythms
• The hypothalamus controls many
circadian rhythm.
Body temperature
Adrenocortical activity
Eosinophil count
Renal secretion
Sleeping and wakefulness.

70. Sexual dimorphism
• Several hypothalamic nuclei are sexually dimorphic
i.e. there are clear differences in both structure and
function between males and females.
. The importance of these changes can be recognised by
differences in sexual behaviour between males
and females.

71. Clinical Disorders Associated With Hypothalamic
Lesions
• The hypothalamus may be the site of inflammation, neoplasm, or
vascular disorder.
• Its widespread influence on many homeostatic and behavioral
functions means that a lesion of the hypothalamus will produce a
large number of different syndromes

72. • Obesity and Wasting
• Severe obesity can occur as the result of hypothalamic lesions
• Associated with genital hypoplasia or atrophy
• Severe cachexia is suggestive of damage to the hypophysis (pituitary gland)
• Sexual Disorders
• In children, there may be sexual retardation and, rarely, sexual precocity with
hypothalamic lesions
• After puberty, the patient with hypothalamic disease may have impotence or
amenorrhea
Clinical Disorders Associated With Hypothalamic
Lesions

73. • Hyperthermia and Hypothermia
• Hyperthermia - Head injury or following surgical operations in the region of
the hypothalamus
• Hypothermia also can follow a lesion of the hypothalamus
• Cranial Diabetes Insipidus
• Diabetes insipidus results from a lesion of the supraoptic nucleus.
• Large volumes of urine of low specific gravity
• Extremely thirst and drinks large quantities of fluids
Clinical Disorders Associated With Hypothalamic
Lesions

74. • Disturbances of Sleep
• The occurrence of either frequent short periods of sleep during the waking
hours or insomnia has been observed in patients with hypothalamic lesions
• Emotional Disorders
• Attacks of unexplained weeping or laughter, uncontrollable anger, depressive
reactions all have been observed in patients with hypothalamic lesions.
Clinical Disorders Associated With Hypothalamic
Lesions

75. • Horner’syndrome.
It is a syndrome due
to lesion in the
sympathetic
pathway.
Clinical Disorders Associated With Hypothalamic
Lesions

76. Is observed frequently with a variety of cerebral lesion
(infract, haemorrhage, meningitis , encephalitis) that
do not involve hypothalamus
And with many type of local hypothalamic diseases
(trauma, surgery , vascular lesion )
Clinical Disorders Associated With
Hypothalamic Lesions
SIADH

77. A moderate reduction in serum sodium concentration
is a common finding in patient with acute intracranial
disease and post operatively in neurosurgical patient.
Mechanism of hyponatremia in these case, ANP
That is found mainly in the wall of cardiac atria but also
in neuron surrounding the third ventricle in the
anteroventral hypothalamic region.
Clinical Disorders Associated With
Hypothalamic Lesions
Cerebral salt wasting syndrome

78. Kallmann syndrome
• This syndrome characterised by failure to start puberty, primary
amenorrhoea and anosmia.
• The GnRH releasing neurones originate in an area of the
developing brain called the olfactory placode. Then it passes
through the cribriform plate into the olfactory bulb where the
sense of smell is generated. From there it migrates to the
hypothalamus.
HYPOTHALAMUS 78

79. Kallmann Syndrome
• Any problems with the development of the
olfactory bulb will prevent the progression of the
GnRH releasing neurones through it. If the releasing
neurones are prevented from reaching the
hypothalamus, no GnRH will be released.
• So in turn, no FSH or LH will be released which
results in the failure of puberty and deficient
production of testosterone in men, oestrogen and
progesterone production in women.
HYPOTHALAMUS 79

80. Reference
Snell Clinical Neuroanatomy 8th ed.