lecture 4 - brain and cranial nerves part 1 Flashcards
(155 cards)
1
Q
brainstem includes (3)
A
medulla oblongata, pons, midbrain
2
Q
main parts of the brain in categories (4)
A
brainstem
cerebelum
diencephalon
cerebrum
3
Q
diencephalon (3)
A
thalamus, hypothalamus, epithalamus
4
Q
cerebrum (1 = 4)
A
cerebral hemisphere
- cortex and lobes
- basal ganglia
- limbic system
- ventricles
5
Q
brain is protected by (2)
A
cranial bones
cranial meninges
6
Q
cranial meninges (3)
A
dura mater
arachnoid mater
pia mater
7
Q
how does dura mater differ in brain to spinal cord (3)
A
brain
two layers
- periosteal - superficial
- meningeal - deep
layers are fused except when they separate to enclose venous sinuses
no epidural space around brian
8
Q
3 extensions of dura mater
A
falx cerebri
falx cerebelli
tentorium cerebelli
9
Q
falx cerebri
A
extension of dura mater
separates cerebral hemispheres (down the middle)
10
Q
falx cerebelli
A
extension of dura mater
separates cerebellar hemispheres
11
Q
tentorium cerebelli
A
extension of dura mater
separates cerebrum from cerebellum
12
Q
how does blood flow to the brain
A
vai internal carotid and vertebral arteries
13
Q
how does blood flow away from the brain
A
vai dural venous sinuses that drain into internal jugular veins
14
Q
blood brain barrier function
A
protects brain cells by preventing harmful substances in blood from entering the brain
15
Q
BBB components (3)
A
tight junctions - seal endothelial cells of brain capillaries
thick basement membrane - surround endothelial cells
astrocytes pressed against capillaries - secrete substances that allow selective passing of molecules from blood to neurons
16
Q
what can cross teh BBB (3, with examples for each)
A
lipid soluble substances - alcohol, O2
water soluble substances - glucose
other substances like ions travel very slowly
17
Q
what cannot cross the BBB/ damage it?
A
big molecules like proteins cant cross
trauma, inflammation, toxins can breakdown BBB
18
Q
CSF, what is it?
A
colourless liquid that bathes the CNS
- composed of water, with a bunch of small things like O2, glucose, proteins etc
19
Q
how much CSF do we have around the brain at a given time
A
80-150 ml
20
Q
CSF functions (3)
A
mechanical protection - shock absorption
chemical protection - maintain optimal environment for neurons
circulation - medium for exchange of nutrients and waste between blood and nervous tissue
21
Q
ventricles of the brain (4)
A
two lateral
third
fourth
all CSF filled
22
Q
where are the two lateral ventricles located
A
in each hemisphere of the cerebrum
separated by septum pellucidum
23
Q
septum pellucidum
A
separates the two lateral ventricles
24
Q
where is the third ventricle located
A
along midline superior to hypothalamus, between left and right halves of the thalamus
25
where is the forth ventricle located
between the brainstem and cerebellum
26
interventricular foramen
space where lateral ventricles and third ventricle are connected
27
where is CSF produced
in the choroid plexuses, by ependymal cells
28
choroid plexuses
network of blood vessels and cells in ventricles where capillaries are covered in ependymal cells
29
ependymal cells secrete:
CSF via filtration of blood plasma
30
what forms the blood CSF barrier
ependymal cells joined by tight junctions surrounding capillaries + endothelial cells inside capillaries
31
circulation of CSF in detail (
- produced in plexus
(each plexus -> ventricle. eg, CSF produced in third ventricles plexus goes to 3rd ventricle)
- flows down ventricles (lateral, 3, 4)
- subarachnoid space
- arachnoid villi of dural venous sinuses
- then to teh heart and lungs
- blood is then sent to the ventricles plexuses, and the process repeats
32
how is CSF reabsorbed
vai arachnoid granulations
- grape cluster like structure of arachnoid mater that penetrate dural venous sinuses
- 20ml /hour is taken up
33
hydrocephalus
accumulation of CSF in the brain if drainage is blocked (by tumor, inflammation, etc)
- in babies, this allows expension of the skull due to pressure inside, can cause damage to nervous tissue
- drain can be planted to let CSF flow to veins of the neck of abdomen
34
medulla oblongata contains
continuation of the spinal cord, so both ascending and descending tracts, and nuclei
integration centres for body function, reflexes, movement
35
pyramids
white matter form bulges on ventral surface of medulla oblongata
- large motor tracts that pass from cerebrum to cord (corticospinal)
- control voluntary movement of limbs and trunk
- decussate
36
decussation
crossing
37
how does decussation affect the brains control of the body
makes it so teh left half of the body is controled by the right side of the brain and vice versa
38
olives
contain interior olivary nucleus that receives input from cerebral cortex, midbrain, and cord. sends output to cerebellum
- give precision to movements,, controls proprioceptive signals
lateral to pyramids of the medulla oblongata (swelling thing)
39
nuclei of the medulla control many body functions including:
cardiovascular centre
respiratory centre
reflex centre
other smaller centers include, gustatory, vestibular (balance), and somatic sensation
40
pons is located
superior to medulla oblongata in the brainstem
41
pons "bridge" function
connects part of the brain via tracts
- connects right and left sides of cerebellum
42
the pons contains (
- nuclei that help control breathing
- vestibular nuclei (balance)
- nuclei for cranial nerves 5-8
43
midbrain is also known as
mesencephalon
44
mesencephalon extends from what to what
pons to diencephalon
45
mesencephalon contains
cerebral aqueduct which connects third and forth ventricles
sensory + motor tracts, and auditory/visual nuclei
46
anterior portion of the midbrain contains: (1)
cerebral peduncles
47
posterior portion of the midbrain contains (1)
tectum (contains superior and inferior colliculi)
48
cerebral peduncles location
anterior midbrain
49
cerebral peduncles
3 paired bundles of axons
- ascending axons carry info to thalamus
- descending run between cerebrum, pons, medulla, and cord
50
tectum
located in the posterior midbrain
4 rounded nuclei elevations called colliculi
51
superior colliculi
2 of them
- reflex for visual activities like tracking moving things
- stimulate movement of the head, eyes, and neck in response to visual stimuli
52
inferior colliculi
2 of them
- part of auditory pathway, relays impulses from receptors to thalamus
- stimulate movement of the head, eyes, and neck in response to auditory stimuli
involved in startle reflex
53
what part of the brain is involved in the startle reflex?
the inferior colliculi in the tectum of the posterior midbrain
54
substantia nigra
nuclei in the midbrain
- dark in colour
- release dopamine
- located behind peduncles
55
red nuclei
nuclei in the midbrain
- axons from cortex and cerebellum synapse here to coordinate movement of the limbs
56
reticular formation
region throughout brainstem where white and grey matter are in a net like arrangement
57
reticular formation neurons hace both sensory and motor functions (T or F)
true
58
Reticular activating system (RAS) is formed by
the ascending part of the reticular formation
59
RAS stands for
reticular activating system
60
RAS functions to: (3)
- alert cerebral cortex to sensory signals to awaken from sleep
- maintain consciousness, alertness, and attention with stimuli from ears/eyes/etc
- prevent sensory overload by filtering stimuli
61
descending axons in RAS function to: (1)
(what do they maintain)
maintain muscle tone
62
what does the RAS not do?
is does not receive stimuli for the sense of smell
63
where does RAS project its sensory info?
to teh hypothalamus, thalamus, and cortex
64
inactivation of RAS results in
sleep
65
damage to RAS results in
a coma
66
RAS main function in shorter terms (2)
fight or flight response
sleep and waking
67
cerebellum contains what % of brain weight and what % of brain neurons
10% weight, 50% neurons
68
cerebellums surface is
highly folded to increase outer grey matter cortex surface area
69
special names for grey and white matter in the cerebellum
white - arbor vitae
grey - folia
70
functions of the cerebellum (main and subdivisions of main)
evaluate how well movements initiated by motor areas in the cerebrum are actually being carried out
- adjusts postural muscles for balance
- fine tunes voluntary/involuntary movements
- stores memories of learned movements
71
cerebellar hemispheres (left and right) consist of (4)
anterior lobes
posterior lobes
flocculonodular lobe
cerebellar peduncles
72
anterior and posterior lobes of the cerebellum function to
control subconscious
aspects of skeletal muscle movements
73
flocculonodular lobe of the cerebellum functions to
maintain equilibrium / balance
74
cerebellar peduncles function are/function is
white matter tracts that attach the cerebellum to the brainstem
- coordinate muscle movement
has superior, middle, and inferior parts
75
ataxia
loss of ability to coordinate movement due to damage of the cerebellum
76
cerebellum trick to remembering function
alcohol affects the cerebellum, think about what a drunk person is like
(posture, balance, memory, finetuning of movement, uncoordination)
77
diencephalon is located:
between top of brain stem and bottom of cerebrum
78
diencephalon fully surrounds:
the third ventricle
79
thalamus makes up waht % of diencephalon
80%
80
the thalamus is
paired oval masses of grey matter in left and right halves
- connected by interthalamic adhesion in most people
- contains nuclei and tracts
81
thalamus main function
relay station for sensory and motor function
82
thalamus sensory functions (2)
- sensory info (-smell) goes through it to the cerebral cortex
- acts as a filter, only passes a small portion of sensory info it gets to cortex
83
thalamus motor functions
- sends info from cerebellum and corpus striatum to primary motor areas of cerebral cortex
- involved in consciousness, learning, memory, emotions, and cognition
84
how many thalamic nuclei are there? no need to memorize the names
7
85
hypothalamus location
inferior to thalamus
86
how many nuclei does the hypothalamus have across all 4 regions
12 in 4 regions
87
main functions of the hypothalamus
control of the ANS
hormone production
emotions
regulation of eating
body temp control
circadian rhythms
88
4 main regions of the hypothalamus
posterior hypothalamic area
intermediate hypothalamic area
anterior hypothalamic area
preoptic area
89
posterior hypothalamic area L and F
anterior to midbrain
olfaction, feeding reflexes like swallowing
90
intermediate hypothalamic area L and F
anterior to posterior hypothalamic area
connects to pituitary gland (via infuncibulum)
- controls anterior pituitary gland
91
anterior hypothalamic area L and F
anterior to intermediate HA
transport ADH and oxytocin to posterior pituitary gland
92
preoptic area L and F
most anterior part of hypothalamus
regulate certain autonomic activities like body temp
93
hypothalamus - control of the ANS
axons from it extend to brainstem and cord
- stimulate smooth/cardiac muscle, secretions
- eg, regulation of heart rate, GI tract
94
hypothalamus - hormone production
release hormones into capillary network to anterior pituitary which stimulates or inhibits anterior pituitary hormone release
95
hypothalamus - emotions
works with limbic system to express rage, aggression, pain, arousal
96
hypothalamus - regulation of eating
contains thirst centre, feeding centre, and satiety centre
97
hypothalamus - body temp control
senses blood temp and restores regular temp via feedback loops
98
hypothalamus - circadian rhythms
serves as bodys internal clock
- receives visual input from eyes to synchronize to a 24 hour cycle
99
epithalamus location
superior and posterior to thalamus
100
epithalamus contains: (2)
pineal gland, habenular nuclei
101
pineal gland (2)
pea sized
secretes meletonin
102
circumventricular organs lack (CVO)
structures that border the third ventricle and lack a BBB
103
circumventricular organs (3)
parts of hypothalamus
pineal gland
pituitary gland
some other nearby structures
104
CVO functions
- monitor chemical changes in the blood
- allow hormones from hypothalamus to leave brain
105
supposed site where HIV enters the body
CVOs
due to lack of BBB
106
cerebrum allows
higher level thinking
107
cerebrum consists of: (3)
outer cerebral cortex (grey)
inner cerebral cortex (white)
deep grey matter nuclei
108
cerebral cortex has: (3)
cerebral gyri
cerebral fissures
cerebral sulci
109
cerebral gyri
rolls of folds of the cortex
"bulges"
110
cerebral fissures
deepest grooves between folds
- separate lobes
111
cerebral sulci
shallower grooves between folds
112
each hemisphere of the cerebrum is divided into:
4 lobes + one mini lobe
113
each hemisphere of the cerebrum receives sensory and generates motor input to the opposite side of the body because:
of the corpus callosum
114
lobes of the cerebrum (4+1)
frontal
parietal
occipital
temporal
mini lobe = insula
115
frontal lobe function
cognitive functions, emotions, voluntary movement
116
parietal lobe function
processes temperature info, taste, touch, movement proprioception
117
occipital lobe function
processes visual info
118
temporal lobe function
processes memories and integrates them with senses
119
insula function
taste
120
longitundinal fissure
separates cerebrum into left and right hemispheres
121
central cerebral sulcus
separates frontal and parietal lobes
122
lateral cerebral sulcus
separates frontal lobe from temporal lobe
123
parieto-occipital sulcus
separates parietal lobe from occipital lobe
124
association tracts (cerebral white mater)
connect and transmit nerves impulses between gyri in the same hemisphere
125
commissural tracts (cerebral white matter)
connect gyri from one hemisphere to the corresponding gyri of the other
eg. corpus callosum
126
projection tracts (cerebral white mater)
form descending and ascending tracts that transmit impulses form cerebrum to other brain and cord parts
127
3 directions of cerebral white mater tracts
between gyri in same side - association
between gyri on opposite sides - commissural
from gyri to other parts of brain and cord - projection
128
biggest fibre bundle in the brain
corpus callosum
129
the corpus callosum is a:
commissural tract
130
corpus striatum
3 nuclei deep within each cerebral hemisphere
131
functions of the corpus striatum (2)
receive input from cerebral cortex and send output to motor cortex
regulate initiation and termination of movements
132
limbic system parts (general areas)
bunch of structures from teh cerebrum, diencephalon, and midbrain
133
how is the limbic system connected
by the fornix
134
fornix
a white matter bundle that connects the limbic system
135
limbic system functions (3)
establishes emotional states
olfaction
memory
136
hippocampus is involved in:
memory storage and retrieval
137
3 types of areas in the cerebral cortex
sensory
motor
association (control complex integrative functions)
138
sensory areas of the brain function
reception and interpretation of sensory impulses
139
sensory areas of the brain (5)
somatosensory
visual
auditory
gustatory
olfactory
all of them have "primary" in front and "cortex" at the end
140
primary somatosensory cortex
has post central gyrus
- input from touch, pain, tickle, itch
- main function = localization of orgin and intensity of sensation
141
post central gyrus
gyri directly posterior to the central sulcus
141
primary auditory cortex
superior part of temporal lobe, near cerebral sulcus
- interprets basic sound charactaristics like pitch and rhythm
142
primary visual cortex
posterior tip of occipital lobe
- receives impulses that convey info (shape, colour) for vision
142
primary gustatory cortex
in insula
- receives impulses for taste
143
olfactory cortex
in temporal lobe on medial side
- receives impulses for smell
144
motor areas of the brain (4)
primary motor cortex
premotor cortex
brocas area
frontal eye field
145
sensory homunculus
misshaped map of sensory spots
146
motor homunculus
misshaped muscle map of the body
147
why does each region of motor area control skeletal muscles on opposite sides of the body
due to decussation
148
premotor cortex
anterior to primary motor cortex
- controls complex, learned movements
149
frontal eye field
partially in and anterior to premotor cortex
- controls voluntary scanning movement of eyes like reading
150
brocas area
helps to control speech articulation (speaking)
- mainly located in left frontal lobe
151
what does damage to brocas area result in?
the ability to understand remains, but production of speech is impaired
called brocas aphasia or non fluent aphasia
152
153
