Diencephalon Flashcards

1
Q

Diencephalon is the ——— part of the forebrain that occupies——— region of the brain

A

Diencephalon is the caudal part of the forebrain( prosencephalon) that occupies central region of the brain

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2
Q

Subdivisions of the Diencephalon:

A

Subdivisions of the Diencephalon:
• Epithalamus
• Subthalamus (Ventral thalamus)
• Thalamus (Dorsal thalamus)
• Hypothalamus
• Metathalamus

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3
Q

Epithalamus
It is the most ——— part of the diencephalon; it forms a —— like covering over the thalamus.
• Consists of:

A

Epithalamus
• (“Epi” means upon) It is the most dorsal part of the diencephalon; it forms a caplike covering over the thalamus.
• The smallest and oldest part of the diencephalon
• Consists of: pineal body, habenular nuclei, habenular commissure, and the posterior commissure

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4
Q

——— is The smallest and oldest part of the diencephalon

A

Epithalamus

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5
Q

The epithalamus is functionally and anatomically linked to the ——- system; implicated in a number of ——— functions (such as ———), and ———

A

It is functionally and anatomically linked to the limbic system; implicated in a number of autonomic functions (ie. respiratory, cardiovascular, endocrine (thyroid function), and reproductive (mating behavior; responsible for
postpartum maternal behavior).

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6
Q

Pineal gland

• Its main secretion is ————, which regulates the body’s ————.
• It is also thought to produce hormones that inhibit the action of other ——— glands in the body.

A

Pineal gland
• The pineal gland is a small endocrine gland located within the brain.
• Its main secretion is melatonin, which regulates the body’s circadian rhythm.
• It is also thought to produce hormones that inhibit the action of other endocrine glands in the body.

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7
Q

Anatomical structure- Pineal gland
• The pineal gland is small glandular body, approx —mm long.
• It is shaped like a ——, from which its name is derived.
• Two types of cells present within the gland are:
• ———- - hormone secreting cells
• ——— cells - supporting cells.

A

Anatomical structure- Pineal gland
• The pineal gland is small glandular body, approx 6mm long.
• It is shaped like a pine cone, from which its name is derived.
• Two types of cells present within the gland are:
• Pinealocytes - hormone secreting cells
• Glial cells - supporting cells.

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8
Q

• The pineal gland is a midline structure, located between the two ————
• It is attached by a —— or —— to the —— wall of —— ventricle.
• In close proximity to the gland are the ——— of the midbrain

A

• The pineal gland is a midline structure, located between the two cerebral hemispheres.
• It is attached by a stalk or peduncle to the posterior wall of third ventricle.
• In close proximity to the gland are the superior colliculi of the midbrain

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9
Q

Anatomy
• The stalk/peduncle divides into two laminae separated by the —— recess of the —— ventricle
• The superior lamina of the stalk contains the ———
• The inferior lamina contains the ———

A

Anatomy
• The stalk/peduncle divides into two laminae separated by the pineal recess of the 3rd ventricle
• The superior lamina of the stalk contains the habenular commissure (HC)
• The inferior lamina contains the posterior commissure (PC)

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10
Q

• The hormones of the pineal gland are regulatory; they influence the activity of other endocrine glands like——-
• Its effect on these glands are mostly (inhibitory/excitatory?)

A

• The pineal body also secretes a number of polypeptide hormones but their functions are poorly understood.
• The hormones of the pineal gland are regulatory; they influence the activity of other endocrine glands- pituitary, endocrine pancreas, adrenal gland, parathyroid gland and gonads.
• Its effect on these glands are mostly inhibitory- it reduces the synthesis and release of the hormones produced by these glands.

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11
Q

Sexual and reproductive function
• Studies suggest that the pineal gland inhibits the pituitary gland’s secretion of sex hormones:like——-

A

Sexual and reproductive function
• Studies suggest that the pineal gland inhibits the pituitary gland’s secretion of sex hormones: FSH, and LH.
• These hormones aid in the proper development and functioning of the ovaries and testes.
• Thus, it is believed that the pineal gland plays a role in regulating the onset of puberty, while it also inhibits the maturation of genitals until puberty.

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12
Q

• Hormones of the pineal gland reach the pituitary gland through the ——— and the ———.
• With increasing age, the pineal glands become calcified and form- ———

A

• Hormones of the pineal gland reach the pituitary gland through the bloodstream and the CSF.
• With increasing age, the pineal glands become calcified and form- corpora arenacea or brain sand.

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13
Q

Blood Supply
• The main arterial supply to the pineal gland is via the ——— arteries (these arteries arise from the ———artery).
• Venous drainage is via the ———veins.

A

Blood Supply
• The main arterial supply to the pineal gland is via the posterior choroidal arteries (these arteries arise from the posterior cerebral artery).
• Venous drainage is via the internal cerebral veins.

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14
Q

Pineal gland dysfunction can be caused by

A

Pineal gland dysfunction can be caused by pineal tumors, craniopharyngiomas, injuries affecting the sympathetic innervation of the pineal gland, or rare congenital disorders that alter melatonin secretion

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15
Q

The most prominent manifestation of pineal gland dysfunction is a change in the ————.

A

The most prominent manifestation of pineal gland dysfunction is a change in the circadian rhythm.

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16
Q

Production of melatonin by the pineal gland can also be impaired on a smaller scale by factors such as———-

A

unnatural timing of light exposure, delayed bedtimes and rise times etc.

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17
Q

———— are associated with precocious puberty and hypergonadism,

A

Low melatonin levels

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18
Q

———— are associated with delayed puberty and hypothalamic amenorrhea

A

High levels of melatonin

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19
Q

Subthalamus is located ventral to the ——— and lateral to the ———-

A

located ventral to the thalamus and lateral to the hypothalamus only present in mammals).

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20
Q

Subthalamus is only present in

A

Mammals

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21
Q

Subthalamus is defined as the upward continuation of the ———
• Consists of a complex admixture of nerve fibre tracts, grey mater and nuclei (such as the ————)

A

defined as the upward continuation of the midbrain tegmentum
• Consists of a complex admixture of nerve fibre tracts, grey mater and nuclei (such as the zona incerta, reticular nucleus, and the perigeniculate nucleus)

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22
Q

Subthalamus Continues with the rostral (upper) ends of the ——- nucleus and ——
• It is related above to the ———, medially to the ———- and laterally to the ———

A

Continues with the rostral (upper) ends of the red nucleus and substantia nigra
• It is related above to the dorsal thalamus, medially to the hypothalamus and laterally to the internal capsule.

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23
Q

Lesion of Subthalamic nucleus
• Lesion of the subthalamic nucleus produces ——- in the which side
• The involuntary and violent movements (of throwing or flailing type)affecting usually ——— parts of the ——- limbs are the xtic feature of this lesion

A

Lesion of Subthalamic nucleus
• Lesion of the subthalamic nucleus produces hemiballismus in the opposite side
• The involuntary and violent movements (of throwing or flailing type)affecting usually proximal parts of the upper limbs are the xtic feature of this lesion

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24
Q

Recent work indicates stimulation of the subthalamus in cats inhibits the ——— reflex; thus may also be involved in neural control of ———.

A

Recent work indicates stimulation of the subthalamus in cats inhibits the micturition reflex; thus may also be involved in neural control of micturition.

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25
Q

Stimulation of the subthalamus provides the most effective treatment for ——— disease in humans.

A

Stimulation of the subthalamus provides the most effective treatment for late-stage Parkinson’s disease in humans.

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26
Q

Hypothalamus
• Located below the ——— and medial to the ———
• Below the level of the hypothalamic sulcus, it forms the wall of the —— ventricle medially
• Laterally, it is in contact with the ———
• Posteriorly, it merges with the ——- and thru it with the ——— of the midbrain

A

Hypothalamus
• Located below the dorsal thalamus and medial to the subthalamus
• Below the level of the hypothalamic sulcus, it forms the wall of the 3rd ventricle medially
• Laterally, it is in contact with the internal capsule
• Posteriorly, it merges with the subthalamus and thru it with the tegmentum of the midbrain

27
Q

• Anteriorly, the hypothalamus extends up to the ——— and merges with certain —— structures
• Inferiorly it is related to structures in the floor of the — ventricle, which are:

A

• Anteriorly, it extends up to the lamina terminalis and merges with certain olfactory structures
• Inferiorly it is related to structures in the floor of the 3rd ventricle- tüber cinereum, infundibulum, mamillary bodies

28
Q

Hypothalamus , the most —— part of the diencephalon
• it is the most significant component of the diencephalon from a clinical standpoint because lesions result in abnormalities in ———, ——— and/or ——— function.

A

Hypothalamus - (“hypo” = below), the most ventral part of the diencephalon
• it is the most significant component of the diencephalon from a clinical standpoint because lesions result in abnormalities in endocrine, limbic and/or autonomic function.

29
Q

Subdivisions of the hypothalamus:

• It contains scattered neurons and some aggregations, which can be recognized as —— nuclei

A

Subdivisions of the hypothalamus
• Supraoptic region
• Tuberal region
• Mammillary region
• It contains scattered neurons and some aggregations, which can be recognized as hypothalamic nuclei

30
Q

• Supraoptic region - the most important division; it lies above the ———and contains three important nuclei: which are

A

• Supraoptic region - the most important division; it lies above the optic chiasm and contains three important nuclei:
- supraoptic
-paraventricular
-suprachiasmatic

31
Q

• 1) Supraoptic Nucleus - contains neurons that produce ——— hormone; their axons project to the ——— pituitary gland where it is released and enters the blood.

A

• 1) Supraoptic Nucleus - contains neurons that produce antidiuretic hormone (ADH or vasopressin); their axons project to the posterior pituitary gland (neurohypophysis) where ADH is released and enters the blood.

32
Q

Anterior lobe of pituitary gland is called

A

Adenohypophysis

33
Q

Posterior lobe of pituitary gland is called

A

Neurohypophysis

34
Q

Paraventricular Nucleus - contains neurons that produce predominately ———

A

Oxytocin

35
Q

Suprachiasmatic Nucleus - appears to be the hypothalamic nucleus critically involved in controlling ————.

A

Suprachiasmatic Nucleus - appears to be the hypothalamic nucleus critically involved in controlling circadian rhythms (endogenous biological rhythms that have a period of about 24 hours).
The nucleus synchronizes rhythms to light and dark.
• Other circadian rhythms: sleep-wakefulness;
body temperature.

36
Q

Tuberal Region-lies directly above the ——— and contains cells that produce ———, which control ———,——

A

Tuberal Region-lies directly above the pituitary gland and contains cells that produce orexins (hypocretins), which control arousal, wakefulness, and appetite.

37
Q

Mammillary Region
- most ——- portion consisting of the——- which play a role in ————

A

Mammillary Region
- most caudal portion consisting of the mammillary bodies [mammillary bodies play a role in memory & learning]

38
Q

Tuberal region of the hypothalamus contains:

A

ventromedial, dorsomedial, and arcuate nuclei.

39
Q

Mammillary region of the hypothalamus contains:

A

medial, intermediate, and lateral mammillary nuclei, which collectively form the mammillary complex, the tuberomammillary nucleus and the posterior hypothalamic nucleus.

40
Q

Afferent Inputs to the Hypothalamus. The major inputs include:

A

Afferent Inputs to the Hypothalamus. The major inputs include:
a. Nucleus of Solitary Tract- Collects all visceral sensory information from the vagus
b. Limbic System via the fornix- structures such as the amygdala and
olfactory cortex (piriform lobe) project to the hypothalamus and help
regulate behaviors such as eating and reproduction.
c. Retina via direct branches of the optic nerve that go to the suprachiasmatic nucleus
d. Blood- hypothalamus has intrinsic receptors including thermoreceptors and osmoreceptors that monitor temperature and ionic balance; in addition hypothalamic cells are sensitive to hormone concentrations and glucose levels, etc.

41
Q

Maior Efferent Proiections From the Hypothalamus.

A

Maior Efferent Proiections From the Hypothalamus.
a. Neural signals to the autonomic nervous system via projections to the brain stem vagal nuclei and to preganglionic nuclei in the spinal cord
b. Neural signals to the limbic system
c. Endocrine signals to/through the pituitary gland

Ultimately through these connections;
hypothalamus can control
every endocrine gland and alter blood pressure, body temperature and metabolism to maintain body homeostasis.

42
Q

Clinical insight
• The hypothalamus may be affected by
‘———
• It may be compressed by hydrocephalus of —— ventricle.

A

Clinical insight
• The hypothalamus may be affected by
‘inflammation, neoplasm or vascular deficiency
• It may be compressed by hydrocephalus of 3rd ventricle.
• Its lesion causes widespread disturbances in homeostatic and behavioral functions (obesity, sexual disorders, hypothermia or hyperthermia, diabetes, disturbances in sleep and emotional disturbances)

43
Q

Thalamus
• An oval mass of grey substance with some associated ——- layers
• Located adjacent to the —- ventricle above the level of the ——— sulcus
• Medial surfaces of the 2 thalami connected by a mass of grey matter called ——— or ———

A

Thalamus
• An oval mass of grey substance with some associated white layers
• Located adjacent to the 3rd ventricle above the level of the hypothalamic sulcus
• Medial surfaces of the 2 thalami connected by a mass of grey matter called interthalamic adhesion or connexus

44
Q

Thalamus
• Has how many poles with the larger post pole forming the ———-
• Serves as the gateway for all sensory modalities except ———
• The thalami are made up of —— matter that is partitioned by a “—” shaped —— matter structure known as the ————

A

• Has 2 poles with the larger post pole forming the pulvinar
• Serves as the gateway for all sensory modalities except olfaction
• The thalami are made up of grey matter that is partitioned by a “y” shaped white matter structure known as the internal medullary lamina.

45
Q

The lateral surface of the thalamus is related to the ————- which separates it from the ————.
• The superior surface of the thalamus is related laterally to the ———-from which it is separated by a bundle of fibres called ———

A

The lateral surface of the thalamus is related to the internal capsule which separates it from the lentiform nucleus.
• The superior surface of the thalamus is related laterally to the caudate nucleus from which it is separated by a bundle of fibres called stria terminalis

46
Q

• The thalamus and caudate nucleus together form the floor of the central part of the ——- ventricle.
• The medial part of the superior surface of the thalamus is separated from the ventricle by the ——- and a fold of —— mater called ———

A

• The thalamus and caudate nucleus together form the floor of the central part of the lateral ventricle.
• The medial part of the superior surface of the thalamus is separated from the ventricle by the fornix and a fold of pia mater called tela choroidea

47
Q

Thalamic nuclei
• The internal medullary lamina divides the thalamus into ——-, ——— and ——- parts
• The nuclei of the thalamus in these parts are further subdivided into —— and ——-.
• There are how many nuclei found in the thalamus-(most located in the larger ——— part of the thalamus).

A

Thalamic nuclei
• The internal medullary lamina divides the thalamus into anterior, medial and lateral parts
• The nuclei of the thalamus in these parts are further subdivided into dorsal and ventral.
• There are 16 nuclei found in the thalamus-(most located in the larger lateral part of the thalamus).

48
Q

Thalamic nuclei
• The lateral group of thalamic nuclei, can be divided into Dorsal and ventral groups of nuclei:
• which nuclei are found dorsal surface of the thalamus
• which nuclei are found on ventral surface of the thalamus.

A

Thalamic nuclei
• The lateral group of thalamic nuclei, can be divided into Dorsal and ventral groups of nuclei:
• The lateral dorsal nucleus, lateral posterior nucleus and the pulvinar are found dorsal surface of the thalamus
• The ventral anterior (VA), ventral lateral (VL) and the subdivisions of the ventral posterior
(VP) nuclei are ventral surface of the thalamus.

49
Q

Dorsal group of nuclei
• The details surrounding the connections of the dorsal group of nuclei are uncertain.
• They are believed to communicate with the ——— gyrus, which lobes ?

A

Dorsal group of nuclei
• The details surrounding the connections of the dorsal group of nuclei are uncertain.
• They are believed to communicate with the cingulate gyrus, temporal, parietal and occipital lobes, along with other thalamic nuclei.

50
Q

Ventral group of nuclei of thalamus
• The — and — nuclei are believed to be involved in motor cortex activities.
• They both have pathways leading to the ———, ———-, ———and the ———.
• In addition, the —— nucleus also connects to the cerebellum and red nucleus of the roof of the midbrain.

A

Ventral group of nuclei
• The VA and VL nuclei are believed to be involved in motor cortex activities.
• They both have pathways leading to the substantia nigra, premotor cortex, reticular formation and the corpus striatum.
• In addition, the VL nucleus also connects to the cerebellum and red nucleus of the roof of the midbrain.

51
Q

Thalamus .
• In addition, the VL nucleus also connects to the ——— and ———of the roof of the midbrain.

A

• In addition, the VL nucleus also connects to the cerebellum and red nucleus of the roof of the midbrain.

52
Q

Ventral posterior (VP) nuclei
• The VP nucleus- further subdivided into: ——— and ——— nuclei.
• They relay information to the ———- cortex thru the —— limb of internal capsule and the ———(projection fibers)

A

Ventral posterior (VP) nuclei
• The VP nucleus- further subdivided into: VP medial
(VPM) and VP lateral (VPL) nuclei.
• They relay information to the primary somatosensory cortex (Brodmann 3,1,2) thru the post limb of internal capsule and the corona radiate (projection fibers)

53
Q

Ventral posterior (VP) nuclei
• The VP nucleus- further subdivided into: VP medial
(VPM) and VP lateral (VPL) nuclei.
• VPL receives afferent fibers from the ——— and ——- lemnisci;
• VPM receives afferent fibers from the ——— and the ———- tract.

A

Ventral posterior (VP) nuclei
• The VP nucleus- further subdivided into: VP medial
(VPM) and VP lateral (VPL) nuclei.
• They relay information to the primary somatosensory cortex (Brodmann 3,1,2) thru the post limb of internal capsule and the corona radiate (projection fibers)
• VPL receives afferent fibers from the spinal and medial lemnisci;
• VPM receives afferent fibers from the trigeminal lemniscus and the solitariothalamic tract.

54
Q

Medial group of nuclei
• In the medial segment of the thalamus, there are 3 nuclei, which are:

• These clusters of nuclei are responsible for integrating ———, ——— and ——— afferent information with ————.
• The largest of the 3 medial nuclei- the ——— nucleus, has both efferent and afferent connections with the nuclei of the ——— and the ———-cortex.

A

Medial group of nuclei
• In the medial segment of the thalamus, there are 3 nuclei:
• The median nucleus; medial dorsal nucleus; and medial ventral nucleus.
• These clusters of nuclei are responsible for integrating special (olfactory), somatic and visceral afferent information with emotions.
• The largest of the 3 medial nuclei- the medial dorsal nucleus, has both efferent and afferent connections with the nuclei of the hypothalamus and the
Pre frontal ortex.

55
Q

Anterior nucleus
• The anterior nucleus, is connected with the ———- tract (from mammillary nucleus of ———- bodies to hypothalamus) as well as with the ——- and ——— gyrus.
• These structures are integrated with the ——- system as they organize emotion and recent memory.

A

Anterior nucleus
• The anterior nucleus, is connected with the mammillothalamic tract (from mammillary nucleus of mammillary bodies to hypothalamus) as well as with the hypothalamus and cingulate gyrus.
• These structures are integrated with the limbic system as they organize emotion and recent memory.

56
Q

Thalamic tracts
• Ventral spinothalamic- carries sensation of ———- and ——- to the ———
• Lateral spinothalamic- carries impulses of ——— and ——— to the ——— and ——- nuclei
• Dorsal column-medial lemniscus pathway-carries ————-and form recognition from ———- to the ——- nucleus or ——— nucleus

A

Thalamic tracts
• Ventral spinothalamic- carries sensation of crude touch and pressure to the VPL
• Lateral spinothalamic- carries impulses of pain and temperature to the VPL and intralaminar nuclei
• Dorsal column-medial lemniscus pathway-carries proprioception (joint position), tactile discrimination, vibration sense and form recognition from Pacinian corpuscles, Meissner’s plexuses and Golgi tendon organs to the VPL or
VPM

57
Q

Metathalamus
• Consists of the ——— and ——— bodies.

A

Metathalamus
• Consists of the medial and lateral geniculate bodies.
• Also considered as thalamic nuclei

58
Q

Metathalamus
• Consists of the medial and lateral geniculate bodies.
• Also considered as thalamic nuclei
• Medial geniculate body consists of the ———— nucleus
• Lateral geniculate body consists of the ——— nucleus

A

Metathalamus
• Consists of the medial and lateral geniculate bodies.
• Also considered as thalamic nuclei
• Medial geniculate body consists of the medial geniculate nucleus
• Lateral geniculate body consists of the lateral geniculate nucleus

59
Q

Medial geniculate nucleus
• Gives rise to fibers of ———
• These traverse the ——— part of the internal capsule to terminate in the ———- area of the cerebral cortex (broad Mann areas ———).

A

Medial geniculate nucleus
• Gives rise to fibers of auditory radiation.
• These traverse the sublentiform part of the internal capsule to terminate in the ipsilateral auditory area of the cerebral cortex (areas 41, 42, 52 & 22).

60
Q

Lateral geniculate body
• Receives —— impulses from ——-
• Projects fibres to the ——— cortex ( Broadmann areas ——— ) via the ——- and ———- part of internal capsule

A

Lateral geniculate body
• Receives visual impulses from both retinae
• Projects fibres to the visual cortex (areas
17, 18 & 19) via the optic radiation and retrolentiform part of internal capsule

61
Q

Blood Supply
• The thalamus is richly supplied by several blood vessels, notably:
• The ——— branches of the ——— artery
• The ——— branches of the ——— artery and ———artery.

A

Blood Supply
• The thalamus is richly supplied by several blood vessels, notably:
• The thalamogeniculate branches of the posterior cerebral artery
• The thalamoperforating branches of the posterior cerebral artery and posterior communicating artery.

62
Q

Applied Anatomy
• Due to the location of the thalamus, any lesion or insult to the organ will impact ——— structures
• Most insults to the thalamus are ——- in nature.

A

Applied Anatomy
• Due to the location of the thalamus, any lesion or insult to the organ will impact adjacent structures
• Most insults to the thalamus are ischaemic in nature.

63
Q

Applied Anatomy

• Most insults to the thalamus are ischaemic in nature.
• Ischaemia may either be ——— (caused during a therapeutic procedure) or ———- (thrombotic or haemorrhagic).
• If this damage impedes the VPM or VPL nuclei, all ——— inputs would be lost.

A

Applied Anatomy
• Due to the location of the thalamus, any lesion or insult to the organ will impact adjacent structures
• Most insults to the thalamus are ischaemic in nature.
• Ischaemia may either be iatrogenic (caused during a therapeutic procedure) or vascular compromise (thrombotic or haemorrhagic).
• If this damage impedes the VPM or VPL nuclei, all contralateral sensory inputs would be lost.