lecture 15 Flashcards

1
Q

diencephalon is covered by what? what do these two structures form?

A
  • covered by telencephelon

- together, make cerebrum

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2
Q

the diencephalon is a _____ extension of the _____

A

rostral, brainstem

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3
Q

the diencephalon has widespread connections to:

A

motor, sensory and limbic pathways (diverse)

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4
Q

how many and what are the divisions of the diencephalon?

A

epithalamus, thalamus, subthalamus, hypothalamus

4

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5
Q

describe the location of the divisions of the diencephalon

A
  • thalamus is located in the centre of the brain, below the lateral ventricles (2 lobes)
  • epithalamuc sits on either side of the 3rd ventricle (innermost part of the thalamus), on top of the thalamus, below lateral ventricles
  • hypothalamus sits below and infront of the thalamus at the bottom of the 3rd ventricle
  • subthalamus sits on either side of the hypothalamus, below the thalamus
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6
Q

what are the external landmarks of the diencephalon?

A
  • optic chiasm
  • optic tract
  • caudal border of mammillary bodies
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7
Q

describe the optic chiasm as an external landmark

A

forms the anterior boundary of the hypothalamus

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8
Q

describe the optic tract as an external landmark

A

forms the lateral boundary of the hypothalamus

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9
Q

describe the mammillary bodies as an external landmark

A

part of the hypothalamus, form its posterior boundary

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10
Q

what are the internal landmarks of the diencephalon from a coronal section?

A
  • internal capsule
  • 3rd ventricle
  • tegmentum of the midbrain
  • floor of body of lateral ventricles
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11
Q

describe the internal capsule as an internal landmark

A

forms the lateral borders of the diencephalon
(contact w thalamus, subthalamus and hypothalamus)
(fibres of nerve bundles running along outside)

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12
Q

describe the 3rd ventricle as an internal landmark

A

forms the medial boundary of the diencephalon

contact w epithalamus, thalamus and hypothalamus, doesnt pass all the way through the hypothalamus tho

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13
Q

describe the tegmentum as an internal landmark

A

forms the inferior boundary of the diencephalon

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14
Q

describe the lateral ventricles as an internal landmark

A

forms the superior and dorsal boundaries of the diencephalon (contact w epithalamus and thalamus)

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15
Q

what are the internal landmarks of the diencephalon from a sagittal section?

A
  • anterior commissure to optic chiasm

- mammillary bodies to pineal gland

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16
Q

describe the anterior commissure as an internal landmark

A

white matter tract of crossing nevre fibres that sits at the anterior wall of the 3rd ventricle (top of the hypothalamus)

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17
Q

describe the mamillary bodies as an internal landmark

A

pair of small round bodies located at the posterior of the hypothalamus (roughly same level as optic chiasm)

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18
Q

where is the epithalamus located?

A

posterior to thalamus (thalamus forms its anterior boundary)

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19
Q

what does the epithalamus contain?

A
  • pineal gland

- habenular nuclei

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20
Q

describe the pineal gland in relation to the epithalamus

A
  • the base of the pineal stalk is formed from the habenular nuceli and posterior commisures
  • hangs btwn lobes
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21
Q

what is the function of the pineal gland

A

production and secretion of melatonin (controls carcadian rhythm - sleep)

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22
Q

describe the habenular nuclei in relation to the epithalamus

A

small group of nuclei located in the epithalamus

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23
Q

what is the function of the habenular nuclei?

A

functions as a center for the integration of smell, visceral and somatic efferent pathways
(i.e., connects limbic system to the midbrain)

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24
Q

input for the habenular nuclei?

A

stria medullaris

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25
Q

output for the habenuclar nuclei?

A

habenular interpeduncular tract

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26
Q

where is the hypothalamus located?

A
  • inferior to thalamus
  • projects anterior to thalamus
  • at bottom of 3rd ventricle
  • anterior boundary = optic chiasm
  • lateral boundary = optic tract
  • posterior boundary = mammillary bodies
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27
Q

what does the hypothalamus contain?

A
  • mammillary bodies

- infundibulum (pituitary stalk)

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28
Q

what is the overall function of the hypothalamus?

A

visceral control center

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29
Q

what are the four general functions of the hypothalamus?

A

(1) visceromotor (automatic) control area
(2) viscerosensory control area
(3) regulatory area for hormone release from ant pit
(4) endocrine role

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30
Q

describe the hypothalamus as an area for visceromotor control

A
  • controls automatic centers of the brain stem involved in HR, BP, breathing and digestive functions
  • controls somatic motor patterns associated with emotions
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31
Q

describe the hypothalamus as an area for vicersosensory control

A
  • regulates water balance and thirst

- regulates body temp (functions as thermostat)

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32
Q

describe the hypothalamus as a regulatory area for hormone release from the pituitary gland

A

hypothalamic releasing hormones (released from hypo, travel down stalk to) control the release of hormones from the anterior pituitary

33
Q

describe the endocrine role of the hypothalamus

A
  • secretes antidieuretic hormone (aka vasopressin) - functions related to blood volume, body temp, etc.
  • secretes oxytocin - functions related to female reproduction
34
Q

the hypothalamus also has connections to the:

A

limbic system

35
Q

pituitary gland is aka

A

hypophysis

36
Q

pineal gland is aka

A

epiphysis

37
Q

anterior lobe of pituitary gland is aka

A

adenohypophysis

38
Q

posterior lobe of pituitary gland is aka

A

neurohypophysis

39
Q

the anterior pituitary releases which hormoes? where are they produced?

A

ACTH, FSH, LH, TSH, GH, and prolactin

-produced in ant pit (stimulated for release by HRH)

40
Q

the posterior pituitary releases which hormones? where are they produced?

A

ADH, oxytocin

-produced in hypothalamus

41
Q

why are the two lobes of the pituitary so different?

A

ant pit develops from the epithelium of the developing pharynx, post pit develops from the diencephalon (ant grows up into post growing down)

42
Q

where is the subthalamus located?

A
  • inferior & anterior to thalamus:
  • posterior boundary = thalamus
  • lateral boundary = internal capsule
  • medial boundary - hypothalamus
43
Q

what does the subthalamus contain?

A
  • subthalamic nucleus
  • zona incerta
  • ascending sensory pathways
  • motor related tracts
44
Q

describe the subthalamic nucleus in relation to the subthalamus

A
  • largest part of the subthalamus
  • connections with the globus pallidus of the basal ganglia
  • involved in the control of motor function
45
Q

describe the zona incerta in relation to the subthalamus

A
  • horizontally elongated region of gray matter
  • extension of reticular fibres from the midbrain
  • functions related to visceral survival activities (e.g. water/food intake)
46
Q

describe ascending sensory pathways in relation to the subthalamus

A
  • pathways moving through subthalamus on route to thalamus

- include: medial lemniscus and spinothalamic tract (aka spinal lemniscus)

47
Q

describe the motor tracts in relation to the subthalamus

A

these include:

  • cerebellothalamic tracts from the dentate nucleus
  • pallidothalamic fibres from the globus pallidus
48
Q

what are the subthalamic midbrain insertions?

A
  • red nucleus
  • substantia nigra
  • reticular formation
49
Q

where is the thalamus located?

A
  • anterior boundary = interventricular foramen
  • posterior boundary = midbrain
  • superior boundary = lateral ventricles
  • inferior boundary = hypothalamic sulcus
50
Q

describe the shape of the thalamus

A

bilateral masses of gray matter (two symmetrical oval shaped lobes)

51
Q

what is the massa intermedia?

A
  • aka interthalamic adhesion

- medial connection btwn thalami (lobes)

52
Q

what are the functions of the thalamus?

A
  • sensory impulse relay center (except olfaction)

- motor processing through connection with basal ganglia and cerebellum

53
Q

thalamic connections to the cerebral cortex are

A

bidirectional

54
Q

what are the subdivisions of the thalamus?

A
  • anterior
  • medial
  • lateral
55
Q

how are the subdivisions of the thalamus separated?

A

by the internal medullary lamina (band of myelinated fibres)

56
Q

what are the intralaminar nuclei?

A
  • collections of neurons in the thalamus located within the internal medullary lamina
  • are involved in own specific brain functions (dont need to know)
57
Q

describe the anterior nuclear group of the thalamus

A
  • input: hypothalamus, hippocampus, mammillary bodies

- output: cingulate gyrus (limbic systems) for functions in emotion, memory and learning

58
Q

describe the medial nuclear group of the thalamus

A
  • input: thalamus and hypothalamus

- output: prefrontal cortex (frontal lobe) for functions in concious awareness of emotional states

59
Q

describe the lateral nucelar group of the thalamus

A

further subdivided into 3 principal nuclei:

  • ventral
  • lateral posterior
  • posterior
60
Q

describe the ventral principal nuclei

A

further subdivided into:

  • ventral anterior
  • ventral lateral
  • ventral posterior
61
Q

describe ventral anterior and ventral lateral nuclei

A
  • input: reticular formation, substantia nigra, basal ganglia, red nucleus, cerebrum
  • output: premotor cortex, primary motor cortex and supplementary motor cortex for functions in motor control
62
Q

describe the ventral posterior nuclei

A

further subdivided into:

  • ventral posterior medial
  • ventral posterior lateral
63
Q

describe the ventral posterior medial nuclei

A
  • input: ascending trigmenal and gustatory pathways

- output: primary sensory cortex and insula

64
Q

describe the ventral posterior lateral nuclei

A
  • input: sensory information (pain, touch, pressure, temperature and proprioception)
  • output: primary sensory cortex of parietal lobe
65
Q

describe the lateral posterior principal nuclei

A
  • input: parietal lobe

- output: cingulate gyrus for affects in emotional state and integration of sensory information

66
Q

describe the posterior principal nuclei

A

further subdivided into:

  • pulvinar
  • lateral geniculate nucleus
  • medial geniculate nucleus
67
Q

describe the pulvinar

A
  • input: parietal lobes, occipital lobe, temporal lobes

- output: association cortices: occipital lobe, parietal lobes, temporal lobes

68
Q

describe the lateral geniculate nucleus

A
  • input: optic tract (visual information from retina)

- output: primary visual cortex (occipital lobe)

69
Q

describe the medial geniculate nucleus

A
  • input: brachium of the inferior colliculus (auditory information fron inner ear receptors)
  • output: primary auditory cortex (temporal lobes)
70
Q

what is unique about the lateral posterior principal nuclei

A

its a feedback loop

71
Q

what is the reticular nucleus?

A
  • makes up outer covering of thalamus
  • only thalamic nucleus that does not project to cerebral cortex
  • modulates activity of other thalamic nuclei
72
Q

what are the 3 types of neurons in the thalamus?

A
  • relay
  • association
  • diffuse-projecting
73
Q

describe relay nuclei

A
  • receive somatosensory, motor, auditory and visual inputs

- project to functional areas of the cortex

74
Q

which thalamic nuclei are relay?

A
  • anterior nuclear group
  • medial nuclear group
  • lateral nuclear group
75
Q

describe association nuclei

A
  • receive input from association nuclei

- project to association cortices

76
Q

which thalamic nuclei are association?

A
  • dorsomedial nucleus
  • lateral posterior nucleus
  • pulvinar
77
Q

describe diffuse-projection nuclei

A
  • receive input from basal ganglia and limbic system

- project to a wide region of cortex, cross cortical boundaries

78
Q

which thalamic nuclei are diffuse-projecting

A
  • intralaminar nuclei

- midline thalamic nuclei