Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BMS6016 Head, Neck and Brain > Week 8 - Diencephalon, Basal Ganglia, Limbic Systems and Cerebral Cortex > Flashcards

Week 8 - Diencephalon, Basal Ganglia, Limbic Systems and Cerebral Cortex Flashcards

You may prefer our related Brainscape-certified flashcards:
The Brain flashcards
1
Q

What are the 4 components of the diencephalon?

A

Epithalamus
Thalamus (+ Metathalamus)
Subthalamus
Hypothalamus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Define the diencephalon.

Embryologically, what is it derived from?

A

The caudal part of the forebrain

Prosencephalon (forebrain)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the blood supply of the diencephalon?

A

Posterior cerebral artery

Posterior communicating artery

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the function of the diencephalon?

What other areas of the brain does the diencephalon connect with?

A

It is the primary relay and processing centre for sensory information and autonomic control

Limbic system, basal ganglia, primary sensory area (e.g. auditory and visual)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the relation of the 3rd ventricle to the structures of the diencephalon and lateral ventricles?

A

narrow midline cleft between and below the two lateral ventricles which communicate with the 3rd ventricle via the interventricular foramen of Monro

in between the left and right thalami

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the borders of the diencephalon?

roof, floor, anterior/posterior walls

A

roof - choroid plexus of the 3rd ventricle

floor - optic chiasma, infundibulum, mammillary bodies and uppermost part of the mesencephalic tegmentum

anterior wall - laina terminalis, anterior commissure and anterior column of the fornix

posterior wall - stalk of hte pineal gland, posterior commissure and Habenular commissures

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What 5 structures make up the epithalamus?

A
  1. stria medullaris
  2. posterior commissure
  3. habenular nuclei (medial and lateral)
  4. pineal body
  5. paraventricular nuclei (anterior and posterior)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the stria medullaris?

A

A fibre bundle which projects from a number of areas including the limbic system and basal ganglia, to the habenula.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is the posterior commissure?

A

A transversely-orientated commissural white matter tract that connects the two cerebral hemispheres along the midline.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the habenular?

What is its function?

A

part of the epithalamus
receives input from the brain via the stria medullaris.
Outputs to many midbrain areas including neuromodulators - e.g. dopamine, noradrenaline and serotonin

Divided into lateral (limbic) and medial (motor) parts.

Functions include - pain processing, reproductive behaviour, nutrition, sleep-wake cycles, stress responses and learning

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the pineal body?

What is its function?

A

an endocrine gland, made up of pinealocytes which secrete melatonin in response to darkness.
Also secretes many hormones that have important regulatory functions on other endocrine organs including - thyroid, parathyroids, adrenals and gonads.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Thalamic Anterior Nuclear Group

  1. Where is the input from?
  2. Where is the output too?
  3. What are its connections role?
A
  1. input from mammillary bodies (of the hypothalamus)
  2. output to the cingulate cortex
  3. emotional aspects of behaviour, instinctive drives and memory
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Thalamic Medial Nuclear Group

  1. Where is the input from?
  2. Where is the output too?
  3. What are its connections role?
A
  1. input from prefrontal cortex reciprocal fibres, hypothalamus, amygdala and other thalamic nuclei
  2. output to prefrontal cortex
  3. mood and emotion
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the 6 nuclei divisions of the lateral nuclear group?

A 
lateral dorsal 
lateral posterior 
pulvinar 
ventral anterior 
ventral lateral 
ventral posterior
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the two metathalmic nuclei?

Where are they located?

What pathways do they have roles in?

A

medial geniculate nucleus
lateral geniculate nucleus

two bumps off the ventral posterolateral surface of the pulvinar nucleus

MG = auditory pathway 
LG = visual pathway
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Lateral dorsal, lateral posterior and pulvinar nuclei

What is their role?

A

Role in receiving fibres regarding emotion and behaviour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Ventral Anterior Thalamic Nucleus (lateral group)

  1. Where is the input from?
  2. Where is the output too?
A
  1. input from basal ganglia

2. projects axons to premotor cortex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Ventral Lateral Thalamic Nucleus (lateral group)

  1. Where is the input from?
  2. Where is the output too?
A
  1. input from basal ganglia

2. projects axons to primary motor cortex (pre-central gyrus)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Ventral Posterior Thalamic Nucleus (lateral group)

  1. Where is the input from?
  2. Where is the output too?
A
  1. input from brainstem and spinal cord

2. projects axons to somatosensory cortex (relaying sensory information)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Intralaminar Nucleus of the Thalamus

  1. Where is it located?
  2. Where is its input from?
  3. Where is its output too?
A
  1. located within the internal medullary lamina (‘Y’ shaped structure)
  2. input from the brainstem through ascending reticular activating systems (ARAS), and spinothalamic and trigeminothalamic tracts
  3. output to the cerebral cortex and basal ganglia (caudate nucleus and putamen)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the role of the intralaminar nucleus?

What happens if there is a lesion in the intralaminar nucleus?

A

reinforcement of learning and action (mechanism for activation of the cerebral cortex)

Reduction in perception of pain and level of consciousness

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What are the two types of intralaminar nuclei of the thalamus?

A 
centromedian nucleus (larger of the two) 
parafascicular nucleus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the reticular nucleus of the thalamus?

What is its role?

A

a thin layer of cells located on the lateral aspect of the thalamus
located between external medullary lamina and the internal capsule

receives collaterals of thalamocortical and corticothalamic fibres

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Define the subthalamus

A

part of the diencephalon that lies between the posterior part of the thalamus and the tegmentum of the midbrain.
It is also posterior and lateral to the hypothalamus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Define the hypothalamus

A

the ventral-most part of the diencephalon

found below the thalamus and ventromedial to the subthalamus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the relation of the hypothalamus to the 3rd ventricle?

A

it forms the floor and lower part of the lateral wall of the 3rd ventricle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What are the anterior hypothalamic nuclei? (x5)

A
  1. preoptic
  2. anterior hypothalamic
  3. supraoptic
  4. suprachasmatic
  5. paraventricular
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What are the middle hypothalamic nuclei? (x3)

A
  1. dorsomedial hypothalamic
  2. ventromedial hypothalamic
  3. arcuate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What are the posterior hypothalamic nuclei? (x2)

A
  1. posterior hypothalamic

2. nuclei of the mammillary body

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What are the roles of the hypothalamic nuclei?

A

AUTONOMIC - controlling heart rate, urine release from bladder, movement of food through G.I. tract and blood vessel diameter.
ENDOCRINE - regulates pituitary gland secretions that influence: metabolism, ion concentration, sexual development and functions.
MUSCLE CONTROL - e.g. muscles involved in swallowing and stimulates shivering
TEMPERATURE REGULATION - promotes heat loss when hypothalamic temperature increases through sweat production. promotes heat production when hypothalamic temperature decreases through shivering
REGULATION OF FOOD/WATER INTAKE - hunger centre promotes eating and satiety centre inhibits eating. thirst centre promotes water intake
EMOTIONS - large range of emotional influences over body functions, influences stress-related and psychosomatic illnesses, as well as feelings of fear and rage
REGULATION SLEEP-WAKE CYCLE - coordinates responses to the cycle with other areas of brain (e.g. reticular system)
SEXUAL DEVELOPMENT + BEHAVIOUR - stimulates sexual development, arousal and behaviours

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is the function of the preoptic nucleus of the hypothalamus?

A

autonomic (parasympathetic)
temperature regulation
sexual development and behaviour

note - preoptic area is larger in males that females.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is the function of the supraoptic nucleus of the hypothalamus?

A

endocrine function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is the function of the suprachasmatic nucleus of the hypothalamus?

A

Regulation of the sleep-wake cycle - receives direct input from the eyes concerning light-dark cycles and is implicated during jet lag.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is the function of the paraventricular nucleus of the hypothalamus?

A

endocrine function

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is the function of the anterior hypothalamic nucleus?

A

autonomic (parasympathetic)

temperature regulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is the function of the dorsomedial hypothalamic nucleus?

A

sexual development and behaviour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What is the function of the ventromedial hypothalamic nucleus?

A

regulation of food and water intake

sexual development and behaviour

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is the function of the posterior hypothalamic nucleus?

A

autonomic (sympathetic)

temperature regulation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is the function of the lateral hypothalamic area?

A 
autonomic (sympathetic)
muscle control 
regulation of food and water intake 
emotions
regulation of sleep-wake cycle
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What is the function of the arcuate nucleus of the hypothalamus?

A

endocrine

regulation of food and water intake

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What structures make up the basal ganglia?

A 
caudate nucleus 
lentiform nucleus 
amygdaloid 
claustrum 
substantia nigra (in the midbrain) 
subthalamic nucleus
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What structures make up the lentiform nucleus?

A

putamen

globus pallidus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What basal ganglia structures make up the corpus striatum?

A

lentiform nucleus (putamen and globus pallidus), and the caudate nucleus

44
Q

Where is the amygdala found?

A

found within the temporal lobe, deep to the uncus

found at the anterior end of the inferior horn of the lateral ventricles.

45
Q

What is the subthalamic nulceus? Where is it found?

A

traditionally part of the subthalamic region but functionally grouped with the basal nuclei.
Shaped like a biconcave lens.
Lies between thalamus (above) and substantia nigra (below).

46
Q

What are the two cell divisions in the substantia nigra?

A

pars reticulata

pars compacta

47
Q

What is the role of pars compacta?

A

produces dopamine, an inhibitory neurotransmitter.

important in maintaining the striatal pathway (main input of the basal ganglia)

48
Q

What is the function of the globus pallidus in the corpus striatum?

A

it send fibres (efferents) to the substantia nigra pars reticulata and to the thalamus
it receives fibres (afferents) from the striatum (caudate nuclues and putamen)

49
Q

What are the main inputs to the basal ganglia (striatum)?

A
  • Entire Cerebral Cortex - glutamatergic fibres releasing glutamate to excite the striatum or striatal neurons
  • Substantia Nigra - fibres arise in pars compacta and reach the striatum to form the nigrostriatal connections. Nigrostriatal fibres are dopaminergic - releasing dopamine
  • Thalamus - thalamostriatal connections/afferents, which carry glutamate (glutamatergic)
  • Reticular Formation of the Brainstem (midbrain) - afferents are noradrenergic supplying NA to the basal ganglia.
  • Locus Coeruleus - afferent fibres are serotonergic (supplying serotonin)
50
Q

What are the functions of the basal ganglia?

A

Planning and modulation of movement pathways
Control of movement and learning
Coordinating motivation with body movement - inhibiting individual behaviour in a complex social interaction and small voluntary movements

51
Q

What is the function of the mammillary body nuclei?

A

Part of the hypothalamus and limbic system.

Receives afferent fibres from the hippocampus and projects to the anterior nuclei of the thalamus and brainstem.

52
Q

Define the hypothalamus

A

part of the diencephalon
the brain centre for regulation of the autonomic nervous system.
Generally activation of the posterior hypothalamic domain is associated with sympathetic responses and anterior hypothalamic domain is associated with parasympathetic activity.

53
Q

What is the relation of the pituitary gland to the hypothalamus?

A

connected to the hypothalamus via the infundibulum

hormones are produced in the hypothalamus that are released from the posterior pituitary

54
Q

What hormones are produced in the hypothalamus and where?

A

supraoptic nuclei - produces vasopressin
paraventricular nuclei - produces oxytocin

These are transported to the posterior pituitary in the hypothalamohypohyseal tract

55
Q

What releasing factors are produced in the hypothalamus and where?

A 
adrenocorticotropic hormone
luteinising hormone
follicle-stimulating hormone 
thyroid-stimulating hormone 
growth hormone 
prolactin

produced in the anterior pituitary

56
Q

Define interthalamic adhesion

A

flattened band of tissue connecting the two thalami at their medial surfaces

57
Q

Define the hypothalamic sulcus

A

a groove in the lateral wall of the 3rd ventricle, marking the boundary between the thalamus and hypothalamus

58
Q

What is the role of the medial geniculate nucleus?

A

part of the auditory thalamus and represents the thalamic relay between the inferior colliculus and auditory cortex

59
Q

What is the role of the lateral geniculate nucleus?

A

relay centre in the thalamus for the visual pathway. Receives major sensory input from the optic nerve travelling from the retina.
Sends connections to the primary visual cortex.

60
Q

What is the role of the limbic system?

A

processing of memories
creation of emotional states, drives and associated behaviours
reproduction
nutrition - hunger/thirst

61
Q

Describe the limbic system

A

forms a ring surrounding the diencephalon

made up of parts of the cerebrum and diencephalon

62
Q

Describe the basal ganglia motor loop for coordinated movements

What is the role of this motor loop?

A

motor and sensory information from the primary motor and sensory cortices to the putamen via descending tracts, originating from pyramidal cells in the 5th layer of the cerebral cortex.
Putamen either facilitates movements or inhibits/eliminates unwanted movements (which also reduce muscle tension).
It sends this to the thalamus which projects axons to the primary motor cortex completing the closed circuit.

Coordinated voluntary movement following long-term procedure training, e.g. gymnastics.

63
Q

Describe the basal ganglia cognitive association loop

What is the role of this cognitive loop?

A

Axons/projection fibres from the brain (motor and sensory areas) travel to the caudate nucleus.
Two types of feedback - positive when movement is accomplished and negative when movement is unsuccessful.
Fibres travel via the thalamus and sends fibres back to the cerebrum to complete the circuit.

Rewarding learning of movements. (positive/negative feedback)

64
Q

What is the function of the nucleus accumbens?

What other basal ganglia structure is it closely related to?

A

its function is related to addiction

caudate nucleus

65
Q

Describe the interconnections between the cerebral cortex and the basal ganglia

A

Efferent fibres sent from cerebral cortex, intralaminar thalamic nuclei and pars compacta of the substantia nigra to the putamen and caudate - the ‘input’ regions of the basal ganglia.
The lateral (external) and median (internal) globus pallidus receives fibres from the putamen and caudate nucleus
The lateral globus pallidus sends fibres to the subthalamic nucleus which sends fibres back in response to the median globus pallidus.
Median globus pallidus forms connections by sending axons to the thalamus
Caudate and putamen have reciprocal connections to the substantia nigra of the midbrain

66
Q

What is the primary function of the caudate nucleus, putamen and globus pallidus of the basal ganglia?

A

control of posture and movement

67
Q

What is the relation of the caudate nucleus to the ventricles and other structures of the brain?

A

Lies in the wall of the lateral ventricle
Head of the caudate is medial to the internal capsule - forming a prominent bulge in the lateral wall of the anterior horn of the ventricle
The tapered tail of the caudate nucleus follows the curvature of the lateral ventricle into the temporal lobe

68
Q

What is the relation of the putamen and globus pallidus to the ventricles and other structures of the brain?

A

Lie lateral to the internal capsule, deep to the cortex of the insula

69
Q

What structure(s) make up the neostriatum (striatum)?

A

caudate nucleus and putamen

70
Q

What structure(s) make up the paleostriatum?

A

globus pallidus

71
Q

What happens if the basal ganglia becomes damaged?

What disorders are associated with pathophysiology of the basal ganglia?

A

abnormal motor control
alterations to muscle tone
abnormal involuntary movements

Neurodegenerative diseases - Parkinson’s, Huntington’s; Wilson’s disease (heptolenticular degeneration)

72
Q

What causes Parkinson’s disease?

What are the resulting symptoms?

A

Degeneration of the pars compacta of the substantia nigra leading to depleted levels of striatal dopamine

Resting tremor of the upper limb
Progressive akinesia, motor rigidity, flexed posture (in benign essential tremor) and difficulty initiating movements

Symptoms can be exacerbated by anxiety and relieved by alcohol.

Late stages of Parkinson’s - dystonia and chorea (a neurological disorder causes jerky involuntary movements that especially affect the shoulders, hips and face)

73
Q

What causes Wilson’s disease?

What is another name for Wilson’s disease?

What are the symptoms/characteristics?

A

an autosomal recessive disorder of copper metabolism

hepatolenticular degeneration

leads to progressive dementia, dystonia, cerebellar dysarthria and ataxia
characteristic violent (bat's wing) postural tremor
74
Q

What causes Huntington’s?

What are the symptoms/characteristics?

A

An autosomal dominant inherited degeneration of the neostriatum (caudate and putamen)

Causes progressive dystonia, akinesia and dementia
Chorea is characteristic - (a neurological disorder causes jerky involuntary movements that especially affect the shoulders, hips and face).

75
Q

what is a thalamotomy?

when is it used?

A

neurosurgically placed lesions in the region of the ventral anterior and ventral lateral nuclei

used to alleviate some of the motor symptoms associated with disorders of the basal ganglia (rigidity, tremor at rest, dyskinesias) and cerebellum intention tremor, i.e. to relieve the tremor in multiple sclerosis.

76
Q

What are the components of the limbic system?

cerebral/diencephalic/other

A

cerebral components
cortical areas - limbic lob (cingulate gyrus, dentate gyrus and parahippocampal gyrus)
nuclei - hippocampus and amygdaloid body
tracts - fornix

diencephalic components
thalamus - anterior nuclear group
hypothalamus - centres concerned with emotions, appetites (thirst/hunger) and related behaviours

other components
reticular formation (network of interconnected nuclei throughout the brainstem)
77
Q

Describe the Papez circuit

A

information from cortical association areas passes via the cingulate gyrus, cingulum and parahippocampal gyrus to the hippocampus where it is processed
the processed information is transferred to the hypothalamus mammillary bodies via the fornix

the circuit is completed and feedback to the cortex is sent via mammillothalamic fibres relaying information from the hypothalamus to the anterior nucleus of the thalamus. From there, the thalamus projects fibres to the cingulate gyrus, cingulum and parahippocampal gyrus

78
Q

What is the role of the Papez circuit?

A

significant role in memory functions

role in expression of emotion

79
Q

What does the word ‘hippocampus’ mean in Greek?

A

‘hippos’ - horse
‘kampos’ - sea monster

–> seahorse
the hippocampus is sea horse shaped

80
Q

What is the anterior perforated substance?

A

a quadrilateral area of grey matter found anterolateral of the optic tract within the basal forebrain

81
Q

What are the septal nuclei?

A

an area of the brain adjacent to the septum pellucidum and below the rostrum of the corpus callosum
consists of 4 nuclei involved in emotional functioning

82
Q

What is the uncus?

A

the innermost part of the anterior parahippocampal gyrus, part of the medial temporal lobe
part of the limbic system and the posterior portion is part of the hippocampus
houses the primary olfactory cortex, receiving olfactory fibres from the lateral olfactory stria

83
Q

What is the fornix?

What is its function?

A

commissural fibre of the brain forming an integral part of the limbic system

important for the transfer of complex cognitive information between the cerebral hemispheres.

84
Q

What structures does the fornix connect?

A

hippocampus to the mammillary bodies of the hypothalamus

mammillary bodies to the anterior nuclei of the thalamus

hippocampus to the septal nuclei and nucleus accumbens

85
Q

What is the cingulum bundle?

A

a prominent white matter tract that interconnects the frontal, parietal and medial temporal lobes, whilst also linking the subcortical nuclei to the cingulate gyrus

86
Q

What is the function of the hippocampus?

What are the divisions of the hippocampus? Why?

A

emotion and learning
essential for long-term memorisation and memory formation, organisation and storage

CA1, CA2, CA3 and CA4 (cornu ammonis)
each division contains a different cell type and so each has a slightly different function

87
Q

What are the 3 parts of the achicortex?

A

hippocampus
subiculum (continuation of the hippocampus)
entorhinal cortex (continuation of the subiculum)

88
Q

Damage to the hippocampus can result in what?

A

pathological ageing and age-related diseased, i.e. Alzheimer’s
Studies have found shrinkage of the hippocampus in cases of Alzheimer’s disease, leading to amnesia for relatively recent events and an inability to learn new information

89
Q

Describe the limbic circuit for motor expression of emotionality

A

input from the limbic lobe, amygdala and hippocampus to the caudate and nucleus accumbens of the basal ganglia

processing of information can be facilitated or inhibited

feedback via output fibres to the thalamus, from there sends axons onto various regions of the cerebrum, including the motor area (pre-central gyrus)

90
Q

Describe the major hippocampal pathway input and output

A

Input - perforant fibre(s) from the entorhinal cortex

Output - alveus-fimbria-fornix pathway
fibres project to - septal area, mammillary bodies and anterior nucleus of the thalamus.

(*only need to know input and output of pathways)

91
Q

What is the corona radiata?

A

A pair of white matter tracts seen at the level of the lateral ventricles.

inferiorly - these tracts converge as the internal capsule

contains ascending and descending fibres that carry much of the neural traffic to and from the cerebrum

92
Q

What is the relation of brain structures to the lateral ventricles?

A

anterolateral wall of the anterior horn bordered by the caudate nucleus
posterolateral wall of the anterior horn bordered by the thalamus
lateral to the lateral ventricle (not directly bordering) is the putamen

93
Q

What is the choroid fissure?

A

a narrow cleft between the thalamus and fornix to which the choroid plexus is attached

94
Q

What is the septum pellucidum?

A

a thin double membraned structure that separates the anterior horns of the two lateral ventricles

95
Q

What are pes-hippocampi?

A

the name given to two or three grooves on the expanded head of the hippocampus

96
Q

What might cause a limbic lobe disorder?
Why is this?

What happens to the patient in this disorder?

A

alcohol abuse
a diet deficient in thiamine leads to capillary haemorrhages in the upper brainstem and limbic structures.

the patient falls into confusion and coma known as Wernicke’s encephalopathy

97
Q

What is the difference between the extreme and the external capsule?

A

the extreme capsule is a series of white matter tracts found between the insular cortex and the claustrum

the external capsule is a series of white matter tracts found between the claustrum and the putamen of the lentiform nucleus

98
Q

Describe the visual pathway

A
  1. Each visual field is split into a temporal and nasal half
  2. When light passes through the lens of the eye, it projects to the opposite side of the retina
  3. the optic nerve consists of axons that extends from the retina to the optic chiasm
  4. in the optic chiasm axons from the nasal half of the retina cross and project to the opposite side of the brain. axons from the temporal half do not cross.
  5. axons continue on in the optic tract to the lateral geniculate nucleus of the thalamus. (collateral branches synapse with the superior colliculi)
  6. optic radiation consisting of axons from the thalamus project to the primary visual cortex
  7. images from the right side of the visual field project to the left side of the brain, whilst images from the left side of the visual field project to the right side of the brain
99
Q

What cranial nerves can pituitary tumours have an affect on?

A 
II - optic 
III - oculomotor 
IV - trochlear 
V1 - ophthalmic trigeminal 
V2 - maxillary trigeminal 
VI - abducens
100
Q

What can hypothalamic or pituitary tumours cause?

A

under- or over-production of circulating hormones which cause secondary disorders of:

  • growth (dwarfish, gigantism and acromegaly)
  • sexual function (precocious puberty or hypogonadism)
  • body water control (diabetes insipidus and pathological drinking)
  • eating (obesity and bulimia)
  • adrenal cortical control (Cushing’s disease and adrenal insufficiency)

Bitemporal visual field loss - if tumours of the pituitary gland increase in size to compress the optic nerve or optic chiasm (due to being closely adjacent)

101
Q

Describe the olfactory pathway

A
  1. specialised ciliated nerve cells of the olfactory nerve are found in the olfactory epithelium of the nasal cavity.
  2. olfactory nerve axons pass through the cribiform plate of the ethmoid bone
  3. these synapse with the olfactory bulb on the inferior surface of the frontal lobe and preliminary processing of olfactory information takes place
  4. axons from large mitral cells of the bulb leave in the olfactory tract which passes backwards on the basal surface of the frontal lobe
  5. just before reaching the optic chiasm, most olfactory tract fibres are deflected laterally in the lateral olfactory stria
  6. these fibres cross to reach the temporal lobe and terminate mainly in the primary olfactory cortex of the uncus on the inferomedial aspect of the temporal lobe and amygdala
  7. the anterior part fo the parahippocampal gyrus - the entorhinal area - makes up the olfactory association area
102
Q

What is the pyriform cortex?

What is its function?

A

The collective cortices of the primary olfactory cortex and the olfactory association cortex
responsible for appreciating olfactory stimuli

103
Q

What is Anosmia?

What does it result in?

What causes it?

A

damage to the olfactory nerves

loss of sense of smell and flavour of food. (elementary aspects of taste - sweet, salty, bitter, sour - are preserved)

multiple causes:

  • frequently follows head trauma or a meningioma (tumour of the meninges) that invades the olfactory nerves
  • Alzheimer’s - appreceptive agnosia where atrophy of the uncus leaves patients able to detect the presence of odours but unable to identify or discriminate them
  • Semantic dementia - associative agnosia where atrophy of the amygdala and inferior temporal neocortex occurs resulting in patients able to detect odours, match and discriminate them but unable to accurately name/describe/identify them
104
Q

What is tunnel vision?

What can cause it?

A

loss of peripheral vision

pituitary tumour due to close relationship of pituitary gland and optic nerve

105
Q

Why are eating carrots good for your eyes?

A

carrots contain precursors for vitamin A. deficiency in vitamin A is linked to blindness, cataracts and macular degeneration.

carrots also contain lutein an important anti-oxidant that is linked to increasing pigment density in the macular. higher pigment density is linked to decreased risk of macular degeneration.

BMS6016 Head, Neck and Brain (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions