Diencephalon Flashcards
1
Q
The diencephalon is located between ____&____ and extends from the ____ to ____
A
the cerebrum and midbrain
interventricular foramen to the posterior commissure.
2
Q
The diencephalon is divided into two parts: ___&____
A
pars dorsalis (dorsal part) and pars ventralis (ventral part).
3
Q
Pars dorsalis consists of the ___, ____&____
A
thalamus, metathalamus, and epithalamus
4
Q
Pars ventralis consists of the ____&____
A
hypothalamus and subthalamus.
5
Q
The cavity of the diencephalon is the ____ ventricle
A
3rd
6
Q
The thalamus (dorsal thalamus) is a large egg-shaped mass of grey matter located _____ to the ___ventricle.
A
laterally to the third
7
Q
The thalamus has ____ poles &_____ surfaces
A
anterior and posterior ends (or poles)
four surfaces:
superior, inferior, medial, and lateral.
8
Q
The ____ surface of the thalamus forms the greater part of the lateral wall of the third ventricle and is interconnected by the ____ adhesion (connexus).
A
medial surface
interthalamic adhesion
9
Q
The lateral surface of the thalamus is related to the ____ capsule and separated from the ____ nucleus.
A
internal capsule
lentiform nucleus
10
Q
The superior surface of the thalamus is related to the ____ and forms the _____ the lateral ventricle.
A
caudate nucleus
floor of the central part of
11
Q
The inferior surface of the thalamus is related to the ____ anteriorly &____ posteriorly,_____ thalamus separates it from the tegmentum of the midbrain.
A
hypothalamus and ventral thalamus
Ventral thalamus
12
Q
_____ is, a type of tissue lining the third ventricle, is reflected from the lateral wall
A
The ependyma
13
Q
This reflection in the 3rd ventricle is marked by a line called the _____
A
taenia thalami.
14
Q
Below the taenia thalami, there is a narrow bundle of fibers known as the ____ or ____
A
stria medullaris thalami or stria habenularis.
15
Q
The thalamus consists mainly of grey matter (neuronal cell bodies) with a small amount of white matter (nerve fibers).
A
16
Q
The superior surface of the thalamus is covered by a thin layer of white matter called the _____ while the lateral surface is covered by a similar layer called the
A
stratum zonale,
external medullary lamina.
17
Q
The grey matter of the thalamus is divided into ___ main parts by a Y-shaped sheet of white matter called the _____
A
3 main part
internal medullary lamina/septum
18
Q
This lamina is placed vertically and divides the thalamus into
A
lateral, medial, and anterior parts.
19
Q
In the anterior part, there are several nuclei collectively referred to as the anterior nucleus.
A
20
Q
The largest nucleus is in the ___ part
A
Medial part called medial dorsal nucleus
21
Q
In the medial part, the largest nucleus is the medial dorsal nucleus, which can be further divided into a _____&______
A
magnocellular part (anteromedial) and a parvocellular part (posterolateral).
22
Q
In the lateral part, the nuclei can be subdivided into a _____&_____ arranged in two tiers.
A
ventral group and a lateral group
23
Q
The ventral group of the lateral part contains nuclei listed in anteroposterior order: namely
A
Ventral anterior nucleus
Ventral lateral nucleus (also known as ventral intermediate nucleus)
Ventral posterior nucleus
24
Q
Ventral posterior nucleus, which is further subdivided into:
A
Ventral posterolateral nucleus (lateral part)
Ventral posteromedial nucleus (medial part)
25
The lateral group nuclei in anteroposterior order:
Lateral dorsal nucleus (or dorsolateral nucleus)
Lateral posterior nucleus
Pulvinar
26
The thalamus contains additional nuclei, including
Intralaminar nuclei (prff Centro median nucleus) embedded within the internal medullary lamina
Midline nuclei
27
Midline nuclei is scattered@
scattered between the medial part of the thalamus and the ependyma of the third ventricle.
28
Intralaminar nuclei embedded within the _______, it contains numerous nucleus with ___ being the most important
internal medullary lamina
centromedian nucleus being the most important.
29
The afferent thalamic connection
Exteroceptive and proprioceptive impulses ascend through the medial lemniscus, spinothalamic tracts, and trigeminothalamic tract.
Visual and auditory impulses reach the lateral and medial geniculate bodies, respectively.
Taste sensations are conveyed through solitariothalamic fibers
Olfactory impulses likely reach the thalamus through the amygdaloid complex
The thalamus also receives connections from the cerebral cortex, cerebellum, and corpus striatum.
30
Efferent (outgoing) connections from the thalamus
Thalamocortical projections project information to almost the entire cerebral cortex.
Thalamic radiations or peduncles, including anterior, superior, posterior, and ventral bundles, transmit thalamocortical fibers.
Efferent projections from the thalamus also reach the corpus striatum, hypothalamus, and reticular formation.
31
The lateral part of the thalamus consists of ___&___ groups of nuclei.
ventral and lateral
32
The ventral posterior nucleus is important clinically and has two parts: ___&___
ventral posterolateral and ventral posteromedial.
33
Sensations reach the sensory area of the cerebral cortex and the second somatosensory area
34
Connections to the Ventral Anterior Nucleus:
Receives fibers from the globus pallidus and substantia nigra pars reticularis.
Sends efferents to the premotor and supplemental motor areas of the cerebral cortex.
35
Connections to the Ventral Lateral Nucleus:
Receives afferents from the dentate nucleus of the cerebellum and fibers from the globus pallidus.
Efferents from this nucleus project to the motor area of the cerebral cortex.
36
Connections to the Ventral Lateral Nucleus:
Receives afferents from the dentate nucleus of the cerebellum and fibers from the globus pallidus.
Efferents from this nucleus project to the motor area of the cerebral cortex.
37
Connections of Medial Group of Thalamic Nuclei:
The medial dorsal nucleus is involved in controlling emotional states and somatic reflexes.
Damage to this nucleus leads to a decrease in anxiety, tension, and aggression.
38
Connections of Anterior Group of Thalamic Nuclei:
The anterior nucleus is part of the circuit of Papez for recent memory.
It receives fibers from the mammillary body and projects efferents to the gyrus cinguli.
39
Other Connections:
The intralaminar nuclei receive inputs from the body and other brain regions.
Efferents from intralaminar nuclei reach the cerebral cortex and striatum.
Functions of these nuclei are not well understood.
The midline nuclei have connections mainly with the limbic system and play a role in memory and arousal.
40
Thalamic Syndrome: occurs due to
It occurs due to a vascular lesion of the thalamic branch of the posterior cerebral artery
41
Metathalamus: It includes the ___&____ bodies.
medial and lateral geniculate bodies
42
medial and lateral geniculate bodies are oval grey matter situated below the ____ and lat. To____
Pst. Part of the thalamus
Lat to colliculi of the midbrain
43
Medial Geniculate Body: It serves as
a relay station in the auditory pathway and contains medial, ventral, and dorsal nuclei.
44
Connections of the Medial Geniculate Body Afferents
Receives fibers from the lateral lemniscus, either directly or after relaying in the inferior colliculus.
Fibers from the medial geniculate body form the auditory radiation, which passes through the sublentiform part of the internal capsule to reach the auditory areas of the cerebral cortex.
Receives impulses from both cochleae and fibers from the auditory area of the cerebral cortex.
45
Connections of the Medial Geniculate Body Efferents
Neurons in the ventral nucleus of the medial geniculate body respond to different sound frequencies and project to the primary auditory cortex.
Neurons in the dorsal nucleus project to auditory areas surrounding the primary auditory area.
46
Lateral Geniculate Body: It serves as
a relay station in the visual pathway and is located below the pulvinar, anterolateral to the medial geniculate body.
47
Lat. Geniculate bodies Connections - Afferents:
Receives fibers from the retinae of both eyes.
Receives fibers from the primary visual cortex, extrastriate visual areas, superior colliculus, and reticular formation of the pons and medulla.
Receives noradrenergic fibers from the locus coeruleus and serotoninergic fibers from raphe nuclei in the midbrain
48
Lat. Geniculate bodies Connections - Efferents::
Fibers arising from the lateral geniculate body form the optic radiation, which passes through the retrolentiform part of the internal capsule to reach the visual areas of the cerebral cortex.
49
The hypothalamus is a part of the brain located below the thalamus
50
It is divided into three zones: ___, ___&____
periventricular, intermediate, and lateral.
51
The hypothalamus has four regions: ___, ___ , ___&___
preoptic, supraoptic, tuberal, and mammillary.
52
Boundaries of the hypothalamus:
Laterally It is in contact with the internal capsule on the sides
Posteriorly, it merges with the ventral thalamus and the midbrain (tegmentum)
Anteriorly, it extends up to the lamina terminalis and is connected to certain olfactory structures.
Inferiorly, it is related to structures in the floor of the third ventricle, including the tuber cinereum, infundibulum, and mammillary bodies.
53
Subdivisions of the hypothalamus:
The hypothalamus can be divided into three zones namely
& 4 regions
: periventricular, intermediate, and lateral.
There are also four regions within the hypothalamus: preoptic, supraoptic, tuberal, and mammillary.
54
The hypothalamus contains different groups of neurons called nuclei.
55
Some of the nuclei in the medial zone include the
preoptic nuclei, mammillary nuclei, paraventricular nucleus, and others.
56
The ____ nucleus is located in the supraoptic region.
suprachiasmatic nucleus
57
The arcuate nucleus is found in the ____ region
tuberal region
58
The lateral zone contains nuclei such as the ___, ____&____
posterior nucleus, mammillary nuclei, and ventromedial nucleus
59
It works in coordination with higher brain centers, autonomic centers, and the limbic system.
60
Here are the main functions attributed to the hypothalamus:
61
Stimulation of the ____ zone of the hypothalamus stimulates hunger, while stimulation of the ___ zone produces a feeling of fullness. The lateral zone also regulates thirst and drinking.
lateral zone
Medial zone
62
The hypothalamus controls sexual activity in both males and females. It influences gametogenesis, ovarian and uterine cycles, and the development of secondary sexual characteristics. It achieves this by influencing
influencing the secretion of gonadotropic hormones by the pituitary gland.
63
The sexually dimorphic nucleus, located in the_____ area of the hypothalamus, is associated with sexual behavior
preoptic area
64
The hypothalamus influences the activity of the autonomic nervous system, which affects cardiovascular, respiratory, and digestive functions.
65
Sympathetic activity is mainly controlled by ___ parts of the hypothalamus, while parasympathetic activity is controlled by
caudal part
cranial parts of the hypothalamus
66
The hypothalamus has an important role in emotions such as fear, anger, and pleasure.
67
Stimulation of ____ areas of the hypothalamus produces sensations of pleasure, while stimulation of ____produces pain or other unpleasant effects.
lateral area
medial areas of the hypothalamus
68
Control of Endocrine Activity: The hypothalamus influences the production of hormones by the ______ production of_______and ______ hormone by the hypothalamus itself.
anterior pituitary gland and the production of oxytocin and antidiuretic
69
The hypothalamus plays a complex role in the body's response to stress. It controls the autonomic nervous system and hormone release, which are involved in the stress response.
70
Temperature Regulation: Certain neurons in the ____ nucleus of the hypothalamus act as a thermostat to regulate body temperature. When the body temperature rises or falls, mechanisms are activated to bring it back to normal
preoptic nucleus
Proff ANT. HYPOTHALAMIC NUCLEUS( anti. Rise)
Proff PST. HYPOTHALAMIC NUCLEUS( anti. Fall)
71
The ____ hypothalamus acts as an anti-rise center, while the _______ acts as an anti-fall center.
rostral hypothalamus
caudal hypothalamus
72
Biological Clock: The hypothalamus functions as a biological clock, controlling various cyclic activities in the body over a 24-hour period. The sleep-wake cycle (circadian rhythms) is one of the most prominent examples. The _____ nucleus within the hypothalamus is believed to have a crucial role in regulating these rhythms. Lesions in the hypothalamus can disrupt the sleep-wake cycle
suprachiasmatic nucleus
73
The neurohypophysis is controlled by the hypothalamus and releases vasopressin and oxytocin
The adenohypophysis is controlled by the hypothalamus through the release of various releasing factors.
74
Hypothalamus coordinates with higher brain centers, autonomic centers, and the limbic system.
75
_______ secretes ADH
________ Secretes oxytocin & cortocotropin releasing factor (stored in the posterior part of the pituitary gland)
Supra optic nucleus
Para ventricular nucleus of hypothalamus
76
Preoptic nucleus it's function & lesions
Sexually dimorphic: This nucleus is associated with sexual dimorphism, which refers to the physical differences between males and females.
Irregular menstrual cycle and loss of libido: Lesions in this nucleus can lead to irregular menstrual cycles and a decrease in sexual desire (libido).
77
Anterior nucleus it's function & lesions
Heat-loss center: This nucleus is involved in regulating the body's heat loss mechanisms.
Hyperthermia: Lesions in this nucleus can result in abnormally high body temperature
78
Posterior nucleus it's function & lesions
Heat-rise center: This nucleus is involved in regulating the body's heat-generating mechanisms.
Hypothermia: Lesions in this nucleus can result in abnormally low body temperature.
79
Lateral nucleus it's function & lesions
Hunger center: This nucleus is responsible for regulating feelings of hunger.
Anorexia and emaciation: Lesions in this nucleus can lead to decreased appetite, resulting in anorexia (loss of appetite) and emaciation (extreme thinness).
80
Medial nucleus it's function & lesions
Satiety center: This nucleus is responsible for regulating feelings of satiety or fullness.
Obesity: Lesions in this nucleus can lead to increased appetite and weight gain, resulting in obesity.
81
Mammilary body it's function & lesions
Recent memory: This nucleus is involved in recent memory formation.
Wernicke's encephalopathy: Lesions in this nucleus can contribute to the development of Wernicke's encephalopathy, a neurological disorder associated with thiamine (vitamin B1) deficiency.
82
Supraoptic nucleus it's function & lesions
ADH secretion: This nucleus is responsible for the secretion of antidiuretic hormone (ADH).
Diabetes insipidus: Lesions in this nucleus can cause diabetes insipidus, a condition characterized by excessive thirst and the excretion of large volumes of diluted urine.
83
@ the pst end of the two thalami is a group of nuclei called
Habenular nuclei
84
Habenular nuclei is connected to form
Habenular commissure
85
In between the Habenular nuclei is ____
Pineal gland
86
Habenular nuclei, Habenular comissure and pineal gland altogether is called
Epithalamus
87
Sub thalamus is ______ the thalamus
Hypothalamus is ____ the thalamus
Below the thalamus
Ant. Inf to the thalamus
88
In between the thalamus is ____ ventricle
3rd
89
Proff the hypothalamus is divided into mid. & lat. Half
The medial half contains hoe many nuclei
And lateral ____ nuclei
Mid. 10 nuclei
Lat. 1 nuclei
90
In total 11 nuclei
91
In summary the hypothalamus has 3 major functions which are?
Limbic functions
Autonomic nervous functions
Endocrine functions
92
Limbic functions includes
Behavior & emotions
93
Endocrine functions includs
Hormones
94
Autonomic involves
Symp& Para
95
The hypothalamus nuclei are arranged based on the 4 structure that allign on the base of the brain
96
The optic chiasma formed aw a result of the optic nerve
The hypothalamus lies above the optic chiasma
97
Proff
Group of nuclei in Hypo
Pre-orbic
Supra optic
Tuberel
Mammilary group of nuclei
98
Pre-orbic b4 the optic nerve
Supra optic/supra chiasmatic lies above the optic chiasmatic
The tuberel nuclei lies above the Meidan eminence/ tuba scenario
Mammilary group of nuclei
99
The preoptic has ___ nuclei
Supra optic has ___ nuclei
1 preoptic nucleus
4 supra chiasmatic nucleu( above the chiasma
supra optic nuclei( above the the 1 st) ,
Ant. Hypothalamic nucleus,
para ventricular nucleus ( behind the ant.)
100
The tuberal nuclei has ___ nuclei namely
3
Closer to the tubercle = arcurate nucleus
Ant. To the 1st is the central/ ant. Is the ventrol medial nucleus
And behind & above it is dorsoMedial nucleus
101
Mammilary nucleus had ___ nuclei namely
2
Mammilary nucleus = within the mammilary body
Above the mammilary body = Posterior hypothalamic nucleus
102
In the lat. Part of the hypothalamus the nucleus present is
Lat. Hypothalamic nucleus
103
The pineal gland produces 3 hormones which are
Cholestocynine
5 hydroxy tryptamine
Melatonin
104
5 hydroxy tryptamine is called
And functions
Serotonin
Keeps us awake
105
If melatonin falls serotonin increase
106
What's retino chiasmatic tract
There's a connection between the optic chiasma & supra chiasmatic nucleus from the chiasmatic it goes to the pineal gland
That's how light from the eye increase the serotonin secretion
107
Text book
108
The lies in relation to the posterior part of the roof of the third ventricle and in the adjoining part of its lateral wal
epithalamus
109
epithalamus consist of
Pineal body
• Habenular nuclei--medial and lateral
• Stria medullaris thalami (stria habenularis) and habenular commissure
Posterior commissure
110
The attachment of the pineal body to the posterior wall of the third ventricle is through a stalk that has two laminae: which are
superior and inferior.
111
The superior lamina is
traversed by fibres of the _____and the
inferior lamina, by fibres of the ____
habenular commissure
posterior commissure.
112
The pineal body is innervated by postganglionic
sympathetic neurons located in the superior cervical
sympathetic ganglia.
113
The fibres travel through the nervus
conarii. The fibres of this nerve end in the habenularnuclei tract
114
Pineal gland influence on many endocrine
organs like the
hypophysis cerebri, the thyroid, the
parathyroids, the adrenals, and the gonad
115
Pineal hormones travel via blood & csf
116
It has been suggested that the
suprachiasmatic nucleus of the hypothalamus plays an important role in the cyclic activity of the pineal body. This nucleus receives fibres from the retina. In turn, it projecis to
the tegmental reticular nuclei.
Reticulospinal fibres arising
in these nuclei influence the sympathetic preganglionic neurons in the first thoracic segment of the the spinal
oord, Axons of these neurons reach the superior cervical
smpathetic ganglia from which the nervus conarii arises
and supplies the pineal body.
117
A tumour of the pineal body can produce
precocious
Puberty. Melatonin is believed to regulate the onset of
puberty.
118
The habenular nuclei (medial and lateral) are situated in
relation to a triangular depression in the wall of the third
ventricle called the habenular trigone. The trigone lies
in relation to the dorsomedial part of the thalamus.
119
The habenular nuclei receive afferents from several areas included in the limbic system
From hypothalamus, Most of these fibres travel through the stria medullaris to the HN.
Ascending fibres from the tegmentum of the midbrain( brainstem) reach the habenular nuclei through ascending
noradrenergic and serotonergic bundles that travel through the habenulopeduncular tract
120
Efferents from the habenular nuclei reach the pineal
body through the habenulopineal tract. The main
outflow from these nuclei reaches the interpeduncular
nucleus through the habenulopeduncular tract, which
is also called the fasciculus retroflexus
121
The stria medullaris thalami is a bundle of fibres lying
deep to the taenia thalami (along the junction of the medial
and superior surfaces of the thalamus). It begins near the
anterior pole of the thalamus and runs backwards to reach
the habenular region.
122
Many afferents to the habenular
nuclei pass through the stria medullaris thalami.
Some fibres of the stria medullaris thalami cross in the
superior (or anterior) lamnina of the pineal stalk to reach
the habenular nuclei of the opposite side.
123
Several neuromediators have been demonstrated in the
fibres of the stria medullaris. These include
acetylcholine,
noradrenaline, serotonin, and gamma-aminobutyric acid
(GABA).
124
The posterior commissure lies in the inferior lamina of
the stalk of the pineal body.
125
A number of small nuclei are
present in relation to the pst. commissure
These include the
interstitial and dorsal nuclei of the posterior commissure,
the nucleus of Darkschewitsch, and the interstitial nucleus
of Cajal.
