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NSx Neuroanatomy > Diencephalon > Flashcards

Diencephalon Flashcards

1
Q

Components of diencephalon

A

Thalamus

Hypothalamus

Epithalamus (pineal gland, habenular nuclei and habenular commissure)

Subthalamus

(optic nerve and optic tracts)

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2
Q

Internal medullary lamina divides thalamus into what portions?

A

Anterior

Medial

Lateral

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3
Q

Divisions of lateral thalamus

A

Ventral and dorsal parts

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4
Q

What are the additional grey matter components associated with the thalamus?

A

Internal laminar nuclei (found within internal medullary lamina)

Interthalamic adhesion (mass intermedialis)

Lateral geniculate body

Medial geniculate body

Reticular nucleus

(External to external medullary lamina but intimately related to thalamus)

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5
Q

The sheet of white matter superior to thalamus?

A

Stratum zonale

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6
Q

Sheet of white matter lateral to thalamus?

A

External medullary lamina

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7
Q

What is found at the tip of the tail of the caudate nucleus?

A

Amygdala

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8
Q

Where is the hypothalamic sulcus?

A

Between thalamus and hypothalamus

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9
Q

What is the dorsal free margin of the thalamus, which is not related to the more medially located epithalamus?

A

Pulvinar

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10
Q

Of which part of the thalamus is the pulvinar?

A

Lateral dorsal thalamus

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11
Q

What is the principal function of the anterior thalamic nuclei?

A

Adjustment of mood in response to recent memory

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12
Q

Afferent connections of anterior thalamic nuclei

A

Mamillothalamic system (originally from fornix which is originating from hippocampal/parahippocampal portion of temporal lobe)

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13
Q

Where do most of the fibres from fornix which enter the hypothalamus terminate?

A

Mamillary body

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14
Q

Efferent connection of anterior thalamic nuclei

A

Cingulate gyrus

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15
Q

Papez circuit

A

Hippocampal-> fornix-> mamillary body-> anterior thalamic nucleus-> cingulate gyrus

Involved in recent memory

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16
Q

Which part of the Papez circuit is affected in Wernicke’s syndrome?

A

Mamillary bodies undergo degeneration or ischaemia

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17
Q

The function of the dorsal medial nucleus of the thalamus?

A

Adjust behaviour and psychological/physical state in response to mood

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18
Q

Afferent connections of the dorsal medial nucleus of the thalamus

A

All other internal thalamic nuclei

Basal ganglia

Lentiform nucleus

Hypothalamus

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19
Q

Efferent connections of the dorsal medial nucleus of thalamus?

A

Prefrontal cortex

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20
Q

Which thalamic nuclei are concerned with the limbic system?

A

Anterior thalamic

Dorsal medial nuclei

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21
Q

Important afferent connections of the intralaminar thalamic nuclei

A

Ascending reticular formation of the brainstem

All other thalamic nuclei

Ascending pain pathways:

Spinothalamic tract (which also activates reticular formation)

Trigeminothalamic tract

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22
Q

Efferent connections of intralaminar nuclei

A

The whole cerebral cortex

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23
Q

What is the function of intralaminar thalamic nuclei?

A

Cortical arousal

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24
Q

What is the largest intralaminar nucleus?

A

Centromedian nucleus

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25
Connections of the centromedian nucleus Significance?
All other thalamic nuclei Motor cortex Basal ganglia Striatum Motor activity can regulate levels of arousal.
26
Which part of the thalamus is affected in Wernicke's syndrome?
Dorsal median nucleus
27
What are the three lateral dorsal tier thalamic nuclei from ventral to dorsal? DPP
Lateral dorsal nucleus Lateral posterior nucleus Pulvinar
28
Connections of lateral dorsal nucleus
Similar to the anterior nucleus of thalamus, can be thought of posteriorly displaced anterior nucleus. Mamillothalamic and thalamocingulate connections.
29
Connections of the lateral posterior nucleus
Two-way connection with superior parietal lobule and all other thalamic nuclei
30
Connections of pulvinar
Connections with all thalamic nuclei including strong connections with LGN and MGN Two-way connections with sensory association cortices.
31
Brodman area- Primary occipital cortex
17
32
Brodman areas- Visual association cortex
19, 20
33
What is the difference between primary visual cortex and secondary/tertiary?
Initial sensory information is received in the primary cortex. Subsequently, it is projected to the secondary area of visual association cortex where it is processed Tertiary cortex compares new visual experience with previous information and tries to recognise it.
34
Function of primary sensory cortices
Receive information
35
Function of secondary sensory cortices?
Process information
36
Function of tertiary sensory cortices?
Compare to previous experiences to recognise object. E.g. with written text Primary receives image Secondary identifies that it is English Tertiary reads it
37
Secondary and tertiary sensory cortices together are known as?
Association areas
38
Consequence of pulvinar damage
Sensory aphasia Unable to make sense of sensory information though the primary cortices are able to receive it.
39
What is the general arrangement of ventral tier nuclei
5 ventral tier nuclei Two in front Then three combined nuclei dorsally.
40
What is the most anterior ventral tier nucleus?
Ventral anterior nucleus
41
What is the second most anterior ventral tier nucleus?
Ventral lateral nucleus
42
Which of the ventral tier nuclei are concerned with motor function?
Ventral anterior nucleus Ventral lateral nucleus
43
What are the three nuclei that make up the ventral posterior nucleus?
Ventral intermediate nucleus Ventral posteromedial nucleus Ventral posterolateral nucleus
44
Connections of the ventral anterior nucleus of the thalamus
Ventral anterior nucleus receives fibres from basal ganglia (specifically pallidothalamic fibres) and projects to the prefrontal cortex and premotor area. Involved in planning motor movements
45
Connections of the ventral lateral nucleus?
Receives fibres from the corticopontocerebellar loops either via dentorubrothalamic pathway or dentothalamic pathway Projects to SMA and 1o motor area Again involved in planning and executing motor functions
46
Connections of ventroposterolateral nucleus
Receives medial lemniscus (dorsal columns) Spinothalamic tract Fibres ascend to the primary somatosensory cortex
47
Features of the thalamic syndrome
Thalamic injury, especially to sensory nuclei of VPN initially presents with contralateral hemianaesthesia This may progress to intractable hemibody pain due to aberrant new intrathalamic connections. Patients will often become depressed and may commit suicide.
48
Thalamic hand
Can be a consequence of damage to the motor component of the thalamus The hand becomes pronated, and flexed, MCPJ flexed, ICPJ extended
49
The function of the ventral posteromedial nucleus of the thalamus?
Similar to ventral posterolateral but for head and neck Receives afferents from the trigeminothalamic tract and tractus solitarius Sends fibres to primary sensory cortex.
50
Function of VIM
The relay nucleus of the thalamus for the cerebellum, receiving input from the opposite cerebellum via the superior cerebellar peduncle. Output is to the primary motor cortex (Brodmann’s area 4) and premotor cortex
51
Connections of the reticular nucleus
Main regulator of thalamic activity Receives information from the whole cerebral cortex Receives information from ascending reticular formation Sends fibres to all nuclei of the thalamus
52
3 basic functions of the hypothalamus
Part of the limbic system Intimately related with the function of ANS Endocrine function
53
AP extent of the hypothalamus
From midbrain to the optic chiasma Sheet of grey matter
54
Swelling on the undersurface of the hypothalamus
Tuber cinereum Mamillary bodies
55
What divides the hypothalamus into right and left areas?
The ventral part of the third ventricle
56
From which part of the parahippocampal formation do most of the fibres of the fornix originate?
Subiculum
57
Divisions of hypothalamus
Can be divided into medial and lateral side by an imaginary plane which is in line with the entry of the fornix and exit of the mamillothalamic tract
58
What fibres run from the frontal-orbital and septal area through the lateral hypothalamus into the brainstem
Medial forebrain bundle
59
What is the septal area of the brain?
Septal nuclei (medial olfactory area) structures below he rostrum of the corpus callosum, anterior to the lamina terminalis .The septal nuclei are composed of medium-size neurons which are classified into medial, lateral, and posterior groups. The septal nuclei receive reciprocal connections from the olfactory bulb, hippocampus, amygdala, hypothalamus, midbrain, habenula, cingulate gyrus, and thalamus.
60
What are these hypothalamic nuclei?
Pre-optic nuclei
61
What is the function of the pre-optic nucleus?
Contains dimorphic nucleus which is thought to be involved in determining sexuality Involved in the regulation of sexual function via the mediation of release of adenohypophyseal gonadotrophs through GnRH
62
What is this nucleus?
Lateral hypothalamic nucleus
63
The function of the lateral hypothalamic nucleus
Involved in the regulation of hunger Excessive stimulation can provoke anger Involved in regulation of thirst Located close to sympathetic outflow of the hypothalamus
64
What is the green nucleus?
Ventromedial nucleus of hypothalamus
65
What is the function of the ventromedial nucleus of the hypothalamus
Satiety Happiness
66
Divisions of medial hypothalamus from anterior to posterior
Pre-optic region Supra-optic region Tuberal region Mamillary region
67
What is the nucleus in the pre-optic region of hypothalamus?
Pre-optic nucleus
68
Which nuclei are in the supra-optic region of the medial hypothalamus?
Suprachiasmatic nucleus Anterior thalamic nucleus Supraoptic nucleus Paraventricular nucleus
69
What is the function of the suprachiasmatic nucleus?
Involved in the regulation of circadian rhythms (biological clock) Receives afferent fibres from optic chiasm- allows to determine light exposure, using ratio of light and darkness can be used to determine season Connected to epithalamus Pineal gland involved in circadian rhythmn
70
Function of the anterior hypothalamic nucleus?
Involved in the regulation of body temperature- helps with cooling Sends efferents to the spinal cord and is involved in sweat production and cutaneous vasodilation Involved in PNS
71
Functions of the supraoptic nucleus
Produces ADH which is stored in and released after traversing axons from the neurohypophysis
72
Function of the paraventricular nucleus?
Involved in the production and release of oxytocin by the neurohypophysis
73
How is the suprachiasmatic nucleus involved in circadian rhythms?
Receives efferents from the optic chiasma and has projections to the habenular nuclei and subsequently to the pineal gland.
74
Which substances are secreted by the pineal gland?
Melatonin 5HT CCK
75
What is the name for the bundle of neurones projecting from the supraoptic and PVN of the hypothalamus?
Supraopticohypophyseal tract
76
What are the three important nuclei of the tuberal region?
Arcuate nucleus Ventromedial nucleus Dorsomedial nucleus
77
Location of the arcuate nucleus?
In the median eminence of the tuberal region of the hypothalamus
78
Function of the arcuate nucleus?
Projects axons to the hypothalamic hypophyseal portal system. Releases substance release factors to stimulate the anterior pituitary to produce its endocrine mediators.
79
What is the name of the bundle of fibres projecting from the arcuate nucleus to the portal system?
Tuberohypophyseal tract
80
Function of the ventromedial nucleus of the hypothalamus?
Satiety and happiness centre When stimulated, inhibits the nucleus of the lateral hypothalamus that is involved in hunger.
81
Function of the dorsomedial nucleus
Punishment centre Connects with lateral hypothalamus and is involved in the regulation of hunger.
82
Important nuclei of the mammillary region of the hypothalamus
Mamillary nuclei Posterior hypothalamic nucleus
83
Function of the mamillary nuclei?
Involved in eating mechanisms Involved in Papez circuit
84
What is the effect of vitamin B1 deficiency on the brain?
May develop haemorrhagic lesions in the mammillary body. The dorsal medial nucleus of the thalamus Periaqueductal region of brainstem Superior and inferior colliculi Wernicke-Korsakoff syndrome.
85
Function of the posterior hypothalamic nucleus
SNS Generation of heat through shivering and minimising heat loss through peripheral vasoconstriction.
86
Arrangement of the fornix
Alveus Fimbriae Crus Body Columns
87
Connection of amygdala to the hypothalamus is via what WM structure?
Striae terminalis and second pathway ventral amygdaloid fugal pathway
88
What is the dorsal longitudinal fasciculus?
A descending pathway from the anterior hypothalamus carrying PNS efferents to the PNS nervous outflow- craniocaudal.
89
From what does adenohypophysis develop?
Rathke's pouch which is a diverticulum of orally derived tissue
90
Cranipharyngioma
Meant to be an embryological neoplastic remnant of Rathke's pouch
91
What is the most common supratentorial tumour in children?
Craniopharyngioma
92
What is the only sensory pathway not to synapse in the thalamus before reaching the cerebral cortex?
Olfactory
93
White matter sheets of the thalamus
Rostrally covered with stratum zonale Laterally with external medullary lamina Divided into three parts by internal medullary lamina
94
Divisions of the lateral thalamus
Into two tiers: Dorsal tier containing lateral dorsal, lateral posterior, pulvinar nuclei Ventral tier containing the ventral anterior nucleus, ventral lateral nucleus, ventral posterior nucleus, medial and lateral GN.
95
What thalamic nuclei are not included in the three part schematic
Reticular nucleus Intralaminar nuclei Midline nuclei located in the medial surface of the thalamus in the interthalamic connection
96
Categorisation of thalamic nuclei
Specific relay nuclei Non-specific thalamic nuclei Association nuclei
97
Specific relay nuclei
Anterior nucleus Ventral tier of lateral nucelar group: ventral anterior, lateral, posterior, MGN, LGN)
98
Anterior nucleus
Receives input from the hypothalamus (mamillary bodies and mamlliothalamic tract) and projects to the cingulate gyrus
99
Ventral anterior and ventral lateral nuclei
Basal ganglia and cerebellar input Project to motor and premotor cortices
100
Ventroposterolateral nucleus
Receives somatosensory input from medial leminscus and spinothalamic tract
101
Ventroposteromedial nucleus
Somatosensory information from the sensory nuclei of the trigmeinal nerve
102
Medial geniculate nuclei
Receive input from the cochlear nuclei projecting to the transverse gyrus of Heschl
103
Lateral geniculate nucleus
Receives input from retinal ganglion cells and projects to the calcarine sulcus
104
Nonspecific thalamic nuclei
Centromedian Reticular Midline nucleus
105
Centromedian nucleus
Largest intralaminar nuclei Receives input from cortex and globus pallidus Projects to the caudate and putamen Involved in reticular activating system
106
Reticular nucleus
Receives input from collateral branches of thalamocortical and corticorthalamic fibres and projects to other thalamic nuclei Modulates influence of thalamus on cortex
107
Midline nucleus
Receives input from brainstem reticular formation and projects to limbic structures such as the amygdaloid nucleus and cingulate gyrus
108
What are the association nuclei of the thalamus
Medial nucleus (dorsomedial nucleus) Dorsal tier of lateral nuclei (lateral dorsal nucleus, lateral posterior nucleus, pulvinar)
109
Dorsomedial nucleus
Receives input from olfactory cortex, amygdaloid nucleus, the hypothalamus. Reciprocal connections with association cortex of frontal lobe Concerned with affective behaviour
110
Lateral dorsal nucleus
Part of the limbic system Receives afferents from hippocampal formation, projects to cingulate gyrus
111
Lateral posterior nucleus
Unknown afferents Projects to somatosensory cortex of the parietal lobe
112
Pulvinar
Receives input from the superior colliculus Also from sensory association areas of parietal, temporal, and occipital lobes, projecting back to the same areas.
113
Describe the vascular territories of the thalamus
Four vascular territories Chiefly supplied by small perforating end-arteries from the PCA Anterior: polar arteries, PComm Paramedian: thalamoperforating branches from the P1 segment of the PCA (either unilateral or bilateral) Lateral: Thalamogeniculate artery from P2 Posterior: Medial posterior choroidal artery or posterior branch of lateral posterior choroidal artery May also receive additional blood supply form the anterior choroidal artery
114
Draw the blood supply of the thalamus
115
Bilateral medial thalamic nuclear group infarction Artery of Percheron occlusion
116
Gerard Percheron
French neurologist
117
Epidemiology of artery of Percheron
Estimated prevalence of 33% 4-18% of all thalamic strokes
118
Gross anatomy of artery of Percheron
Solitary arterial trunk that branches from proximal PCA to supply paramedian thalami and rostral midbrain bilaterally Occasionally it may supply the anterior thalamus, esp if polar arteries absent
119
Sensory disturbance in thalamic pathology
Results from lesions affecting VPL and VPM Can be positive or negative, either sensory loss or hemibody pain affecting the contralateral side. Most frequently involves proprioceptive input can be distinguished from cortical sensory loss due to loss of vibratory sense which is often spared in the parietal sensory loss. Pain often felt close to skin and can occur spontaneously Thalamic paraesthesia predominantly affects the circumoral region and distal part of limbs.
120
Motor disturbance in thalamic lesions
Result from lesions in ventral anterior and ventral lateral nuclei interrupting connections between the thalamus and extrapyramidal motor system Thalmic disturbances to motor function may result in hemiataxia and abnormal involuntary movements e.g. action tremor or choreoathetosis The affected hand may assume abnormal posture- thalamic hand May involve transient contralateral hemiparesis (thought to be due to extension into internal capsule rather than isolated thalamic pathology.
121
Thalamic hand
Wrist pronated and flexed at CMC and MCPJ with hyperextension at the IPJ
122
How to distinguish thalamic lesions causing coma vs midbrain
If there is midbrain involvement then there may be presence of oculomotor nerve paresis whereas pure thalamic lesions exhibit small, diencephalic pupils
123
Affective disturbances in thalamic lesions
Tend to result from lesions in anterior and dorsomedial nuclei that interrupt connections with limbic system structures and frontal cortex May result in apathy, disinterest, lack of initiative or drive. Less often, agitation or confusion may develop
124
Memory disturbance with thalamic lesions
Lesions in dosromedial nucleus may result in memory loss
125
Visual disturbance in thalamic lesions
Contralateral hemianopia
126
Broad division of hypothalamus
Into a medial hypothalamic region containing the majority of nuclei Lateral hypothalamic region containing major fibre tracts and a group of diffuse nuclei
127
Borders of the hypothalamus
Rostral border- anterior commissure and lamina terminalis Caudal border merges with midbrain tegmentum
128
Subdivisions of medial hypothalamic area
Supraoptic region (most anterior) Tuberal region Mamillary region
129
Supraoptic region nuceli
Supraoptic Suprachiastmatic Anterior nucleus Paraventricular nuclei
130
Nuclei of the tuberal region of the hypothalamus
Ventromedial Dorsomedial Infundibular
131
Nuclei of mamillary region
Mamilllary body Posterior nucleus
132
Major afferent connections of the hypothalamus
Olfactory and septal areas Hippocampus Amygaloid nucleus Midbrain tegmentum Dorsomedial and midline thalamic nuclei
133
Olfactory and septal afferents to the hypothalamus
Areas are concerned with smell and basic emotional drives Afferents via the medial forebrain bundle
134
Hippocampal afferents to hypothalamus
Sends axons to mamillary bodies via the fornix
135
Amygdaloid afferents to hypothalanus
Sends afferents to the hypothalamus via the stria terminals Associated with complex behaviours
136
Midbrain afferents to the hypothalamus
Reticular formation with diffuse network of fibres Sends axons via the medial forebrain bundle Raphe nucleus and nucleus coeruleus also project fibres via the dorsal longitudinal fasciculus
137
Thalamic afferents to hypothalamus
Axns from dorsomedial and midline thalamic nuclei to the hypothalamus via thalamohypothalamic tract
138
Efferent connections of the hypothalamus
Olfactory and septal areas Anterior thalamic nuclei Preganglionic autonomic neurones of brainstem and SC Posterior pituitary Anterior pituitary
139
Olfactory and septal efferents of hypothalamus
These areas receives hypothalamic efferents via the medial forebrain bundle Concerned with smell and basic emotional drive
140
Hypothalamic efferents Anterior thalamic nuclei
This thalamic nucleus is part of the limbic system Receives hypothalamic axons via the mamillothalamic tract and projects in turn to the cingulate gyrus
141
Hypothalamic efferents: Preganglionic autonomic neurones
Include dorsal nucleus of vagal nerve Intermediolateral cell column Both receive input from the hypothalamus via the dorsal longitudinal fasciculus. The hypothalamic projections to the intermediolateral cell column are relayed in reticulospinal pathways
142
Hypothalamic efferents: Posterior pituitary gland
Receives direct axonal projections from large neurosecretory cells in PVN and supraoptic nuclei of the hypothalamus Carried in the supraoptic hypophyseal tract Involved in the synthesis of ADH and oxytocin
143
Hypothalamic efferents: Anterior pituitary
Neurosecretory cells in infundibular nucleus of the hypothalamus, secretory and inhibitory factors to the pituitary Axoplasmic transport in the tuberoinfundibular tract and are secreted into a capillary bed in the median eminence. From the median eminence, they are transported in the hypophyseal portal veins to a second capillary bed in the anterior pituitary.
144
Autonomic function of hypothalamus
Cardiovascular regulation Body temperature Water balance Food intake
145
Cardiovascular regulation by hypothalamus
Exerts both sympathetic and parasympathetic influences on CV system Posterior hypothalamus -\> sympathetic Anterior hypothalamus-\> PNS These effects are mediated by cardiovascular control centres in reticular formation of brainstem
146
Body temperature regulation by hypothalamus
Anterior hypothalamus contains heat sensitive neurones that sense temperature of blood. Simtualte vasodilation and sweating via PNS Cold-sensitive in posterior hypothalamus increase rate of firing when cold, sympathertic
147
Where is the thirst centre in the hypothalamus
Lateral hypothalamus
148
Location of hypothalamic hunger centre
Lateral hypothalamus
149
Location of hypothalamic satiety centre
Ventromedial nucleus
150
Emotional behaviour regulation by hypothalamus
Integrates limbic and controls autonomic nervous systems Stimulation of lateral hypothalamus-\> fear Ventromedial hypothalamus stimulation-\> placidity and tameness
151
Body temperature Anterior hypothalamic lesion
Hyperthermia
152
Body temperature Posterior hypothalamic lesion
Hypothermia
153
Body weight Destructive lesion of the ventromedial hypothalamus
Obesity
154
Ventromedial hypothalamic lesions, impact on behaviour
May cause episodic outbursts of rage and fear with prominent autonomic component
155
Etymology of thalamus
Comes from greek "thalamos" meaning bedroom or inner chmaber
156
Etymology of die-encephalon
From greek "dia" meaning through Encephalon meaning brain
157
Etymology of pituitary gland
From "pituia" meaning mucous because the gland was thought to bring mucous to the nose

NSx Neuroanatomy (25 decks)

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