Section 2: Internal anatomy of the brain Flashcards
(126 cards)
1
Q
Describe the forebrain
A
q
2
Q
What is the amygdala?
What is its role in the limbic system
A
q
3
Q
The large C shaped structures in each hemisphere is
A
lateral ventricles
4
Q
The anterior horn of the lateral ventricle lies in the
A
frontal lobe
5
Q
The body extends across the
A
frontal and parietal lobe
6
Q
The inferior horn lies in the
A
temporal lobe
7
Q
What lies at the midline where you identified the thalamus
A
3rd ventricle
8
Q
The 3rd ventricle is punctured by
A
massa intermedia (thalamic adhesion)
9
Q
the lateral ventricles commuicate with the third ventricle by
A
interventricular foramen
10
Q
The 3rd ventricle communicates with the 4th ventricle by way of the
A
cerebral aqueduct
11
Q
the cerebral aqueduct passes through the____ under the _____
A
midbrain; superior and inferior colliculi
12
Q
the fibers of the corpus callosum form the ventricular roof on the
A
dorsal surface of the lateral ventricles
13
Q
the head of the caudate lies on the floor of the ______, it creates
A
anterior horn; creates a cavity in the ventral lateral surface of the anterior horn of the lateral ventricle
14
Q
a hollow on the ventral medial surface of the inferior horn is produced by the
A
hippocampus
15
Q
the massa intermedia is not a
A
commisure
16
Q
the 3rd ventricle extends
A
ventrally to a point, like a bird beak
17
Q
the point on the 3rd ventricle extends to the bottom of the brain where it is surrounded by the
A
hypothalamus
18
Q
the medial surface of the posterior horn normally abuts the
A
calcarine sulcus where the sulcus extends inward from the medial surface of the occipital lobe
19
Q
the tectum lies ____ to the aqueduct;
A
dorsal
20
Q
the structure below the aqueduct is
A
the tegementum
21
Q
the tectum is made up of
A
superior and inferior colliculus
22
Q
the cerebellum lies above the
A
4th ventricle
23
Q
what forms the floor of the 4th ventricle?
A
continuation of the tegmentum into the pons
24
Q
What is the function of the blood brain barrier?
A
maintain a stable environment for neurons to function effectively; protecting the CNS from severe fluctuations in ionic concentrations;
25
How is the capillary epithelium specialized for the blood brain barrier?
tight junctions between capillary endothelial cells
endocytic vesicles for intracellular transport
high number of mitochondria indicative of high levels of oxidative metabolism
26
How is passage across the blood brain barrier acheived?
- diffusion of lipid soluble substances related to their oil and water partition coefficient
- facilitative and energy dependent transport of specific water soluble substances
- ion channels
27
What is the reverse pump in the brain? What mediates it?
intracellular transporters within astroglia that move lipophilic molecules of the brain into the blood; likely processes of astroglial cells that encase the capillaries
28
why does the 4th ventricle not have BBB?
it needs to detect changes in the blood chemistry; can detect poisons in the blood and initiate the vomit response.
29
Can leukocytes enter the BBB? Why is this problematic?
yes lymphocytes and marcrophages; can allow HIV infected macrophages and myelin-reactive lymphocytes of MS
30
What causes the BBB to breakdown?
tumor, ischemia, and bacterial infection
31
Stroke is harmful beyond its ischemic effects. WHy?
ischemia can induce breakdown of the BBB and allow toxins and ionic channel influxes which could lead to increased intracranial pressure due to edema and ultimately to death
32
What are the functions of the CSF
maintains constant external environment for the brain, decreases the weight of the brain on the skull and serves as a cushion to protect the brain from mechanical damage
33
The CSF is in equilibrium with
brain extracellular fluid
34
The CSF is turned over
3-4 times per day
35
The average volume of CSF is
| It's rate of production is
140 mL
| 500 mL per day
36
CSF is secreted by
choroid plexus
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the choroid plexus is
a specialized capillary network that is surrounded by cuboidal or columnar epithelium
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The choroid plexus aims to maintain
chemical stability of CSF
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The epithelial cells of the choroid plexus form a
barrier that is responsible for carrier mediated transport that is bidirectional
40
The epithelial barrier made by the CSF
accounts for the contiuous production of CSF and transport of metabolites out of the CSF
41
How does CSF differ from blood plasma?
glucose and protein are lower and CSF is more acidic; it is also clear and normally has no RBCs or and few if any WBCs
42
Where is choroid plexus found?
In the floor of the inferior horn and in body of the lateral ventricle
roof of the third ventricle
inferior part of the lateral ventricle
43
What structure in the spinal cord is vestigial in adults
central canal
44
How does the CSF exit the 4th ventricle?
Foramen of Magendie and the 2 foramina of luschka
45
Where is the foramen of magendie?
opening at he midline at the caudal end of the 4th ventricle
46
where are the foramina of luschka?
at the lateral edges of the ventricle; at the widest extent where CN 8 lies, adjacent to the flocculus
47
CSF flows over the whole brain and spinal cord beneath the
subarachnoid space
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The absorption of the majority of the CSF into the venous system occurs where
in the arachnoid vili or granulations in the walls of the dural sinuses (superior sagittal is the most important for this)
49
An obstructive or non-commicative hydrocephalous is caused by
an obstruction or tumor in the arrows where the ventricular system narrows (intraventricular foramen, cerebral aquaduct, and outlet of the 4th ventricle; blockage of flow occurs here
50
Communicating hydrocephalous occurs when
there is no blockage of flow but arachnid vili are diseased and absorption fails
51
Increased build up of CSF in a communicating hydrocephalous causes
increased intracranial pressure which can be seen by inspecting the fundus of the brain
52
What is papilledema?
retinal vessels of the optic nerve become engorged and dilated due to the increased intracranial pressure
53
Some of the symptoms of increased intracranial pressure are
- headache
- nausea
- vomitting
- cognitive impariment
- decreased level of consciousness
- impaired vision and sixth nerve palsy
54
increased intracranial pressure can affect the
frontal lobe function
55
would you have long tract (descending white matter pathway) signs with intracranial pressure elevation? What are the symptoms
yes; magnetic gait and incontinence
56
Why is the composition of the CSF important?
it is altered in many disease states
57
A white cell count of more than ___ indicates pathology
4/mm^3
58
In what case would protein content be increased in CSF?
protein content may be increased by many pathological processes due to changes in vascular permeability or CSF dynamics
59
The presence of blood in the CSF may indicate
hemmorhagic stroke
60
what are the 3 types of white matter
association fibers, commisural fibers, and projection fibers
61
What are association fibers
connect different regions of the cortex in the same hemisphere
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What are commisural fibers?
connect homologous regions of the cortex of the two hemispheres
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What are projection fibers?
connect areas of the cortex to areas lower in the neuraxis
64
damaging the white matter (axons) produces
many of the same symptoms as damaging the cortex itself.
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the superior longitudinal fasiculus (arcuate fasiculus) connects the
frontal lobe arcing to the temporal lobe
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the arcuate fasiculus interconnects
Broca's area, Wernicke's , area and the auditory cortex
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the inferior longitudinal fasiculus extends from
occipital lobe to the temporal lobe along the occitpitotemporal gyrus
68
the uncinate fasciculus runs
deep to the limen insulae connecting the frontal and temporal cortices
69
what is the limen insulae?
anterior border of the insula
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the uncinate process is thought to associate the
orbital frontal cortex based reward and punishment centers with the temporal lobe based memory representations
71
the cingulum is found
on the medial aspect of the hemisphere deep to the cingulate gyrus
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the cingulum interconnects structures of the
limbic system like the subcallosal gyrus, cingulate gyrus and parahippocampal gyrus and uncus
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it is suspected that the cingulum is involved with
the process of learning to avoid painful stimuli
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association fibers are NOT
oneway, direct paths; they are like an interstate highway
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what are U fibers?
short association fibers that travel only a short distance perhaps to an adjacent gyrus or nearby gyrus
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Reciprocal connections are the
rule, not exception
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The largest of the commisural fibers is the
corpus callosum
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the corpus callosum interconnects
homologous areas of the hemispheres in a spatially oriented fashion
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the frontal lobes are connected via the
genu of the corpus callosum
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the parietal lobes are connected via the
body of the corpus callosum
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the occipital lobes are connected via the
splenium of the corpus callosum
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the anterior commisure connects
the anterior poles of the two temporal lobes
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what do the lobes connected by the anterior commisure contain?
olfactory cortexes
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the hippocampal commisure connects
two hippocampi
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the posterior commisure interconnects the
two sides of the rostral midbrain
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the corona radiata is a type of
projection fibers
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an important component of the corona radiata are
the thalamic radiations, which are interconnections of the thalamic nuclei and their cortical targets
88
the corona radiata becomes the internal capsule when
it passes medially to the lenticulate nucleus
89
what is the crus cerebri?
axons whose targets are in the brainstem and spinal cord descend onto the anterior aspect of the midbrain and the crus cerebri
90
name the 3 types are fibers found in the internal capsule and the crus cerebri
corticospinal, corticobulbar, and corticopontine fibers; axons from the moti
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the head of the caudate nucleus lies behind a bulge in the
anterior horn of the lateral ventricle
92
the roof of the anterior horn of the lateral ventricle houses crossing fibers of the
corpus callosum
93
the hippocampus lies on the medial part of the floor of the
inferior horn of the lateral ventricle
94
the inferior horn of the lateral ventricle lies in the
temporal lobe
95
the parahippocampal gyrus terminates as the
hippocampus
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hippocampus is involved in memory of
spatial relationships
97
axons of hippocampus form a large fiber tract called the
fornix
98
the fornix connects
the hippocampus and hypothalamus in the temporal lobe
99
the fornix curves ventrally at
the anterior end of the 3rd ventricle near the anterior commisure
100
the large cluster of cell bodies that is part of the basal ganglia and follows the path of the lateral ventricle similar to the fornix is
the caudate nucleus
101
the caudate nucleus has
motor and cognitive functions
102
a major function of the thalamus is to
relay motor and sensory info to their respective cortices
103
the anteriro tubercle of the thalmus is on its
dorsal surface anteriorly
104
the pillow shaped bulge on the posterior side of the thalamus is the
pulvinar
105
the anterior tubercle and the pulvinar each mark
nuclear groups within the thalamus
106
the medial and lateral geniculate nuclei are part of the
thalamus
107
the medial geniculate nucleus relays ____info to the
auditory to the Heschl's/transverse gyrus
108
the lateral geniculate nucleus recieves info from the ___ and projects to ___
optic tract; visual cortex in and arounf the calcarine fissure
109
you can find the lateral geniculate nucleus by
following the optic tract to its end
110
the medial geniculate nucelus has fibers that connect it to the___. this bundle is the ___
inferior colliculus; brachium of the inferior colliculus
111
the large nuclear structure located near the uncus at the anterior medial part of the temporal lobe is called the
amygdala
112
the ____ communicates visceral information such as hunger, thirst, anger, fear, and sexual feeling between the brainstem, hypothalamus and cortex
amygdala
113
bilateral damage of the amygdala causes
flattened/blunted emotional and sexual behavior
114
the ____ is a very deep infolding of the cortical tissue
insula
115
the ___ is separated from the caudate by the internal capsule. the 2 structures are called the ___
putamen; striatum
116
the ____ is a fiber tract of huge significance
internal capsule
117
the neck of the corona radiata is called the
internal capsule
118
the anterior limb of the internal capsule carries information to and from
the frontal lobes
119
the posterior limb of the internal capsule carries
somatosensory and motor information from each side of the central sulcus
120
a lesion in the anterior limb is
often silent
121
a lesion in the posterior limb of the IC
dramatic symptoms of sensory loss and paralysis
122
the posterior limb carries visual information via the and auditory info via the
visual radiations; auditory radiations
123
the globus pallidus and the putamen together form the; are they functionally connected?
lenticulate nucleus; no
124
the caudate and putamen send projections to the ___ which sends info to ____
globus pallidus; thalamus
125
at the level of the optic tract the ____and ___ have fused forming the_____
putamen and caudate; ventral striatum
126
the ventral striatum receives info from the ____ and is part of the _____ which controls _____
amygdala, limbic system, emotions
