UNIT 2: Cerebral Hemispheres Flashcards
(125 cards)
1
Q
what divisions are included under the CNS
A
Cerebral cortex
cerebellum
diencephalon
brainstem
spinal cord
2
Q
what divisions are included under the PNS
A
cranial nerves
spinal nerves
3
Q
what are the 2 functional divisions of the NS
A
somatic and autonomic
4
Q
somatic sys
A
aspects of bodily function under conscious and voluntary control (motor control sys and sensory sys)
5
Q
autonomic sys
A
involuntary activities of visceral muscle (smooth muscle, glands) and maintenance of homeostasis
6
Q
where does motor control arise in the somatic NS
A
from the precentral region of the cortex - descending motor tracts thru brainstem and spinal cord
7
Q
what are the 2 divisions of the autonomic NS
A
sympathetic and parasympathetic
8
Q
sympathetic NS
A
vasoconstriction, inc blood pressure, pupil dilation, cardiac acceleration - “flight, fight, fright”
9
Q
parasympathetic NS
A
slowing heart rate, dec blood pressure, pupillary constriction - counteracts preparatory action of sympathetic sys - “energy saving”
10
Q
where does the autonomic NS arise from aka controls from
A
prefrontal crotex, hypothalamus, thalamus, hippocampus, brainstem, cerebellum, spinal cord
11
Q
functional unit of the NS
A
neuron aka communicating tissue… responds to stimulation w inc activity (excitation) or dec activity (inhibition)
12
Q
3 types of neurons
A
sensory (afferent), motor (efferent), interneurons
13
Q
sensory (afferent) neurons
A
classified by sensory properties - ex. mechanical, thermal, pain, visual, auditory, taste
14
Q
motor neurons (efferent)
A
activate response in muscles or glands, known for long myelinated axons, differ by size/conduction velocity/myelination
15
Q
interneurons
A
most common
communication bw other neurons
confined to CNS
16
Q
white matter
A
collections of myelinated axons - in the CNS can be tracts/fibre tracts/ pathways/ peduncles/ fasciculus/lemniscus/ capsules/commissures - in the PNS can be nerve/nerve fascicles
17
Q
Gray matter
A
neural tissue consisting of cells bodies - grouped into a cortex/nucleus/ganglion
18
Q
at week 3 in development of the embryo what are the 3 cell layers
A
ectoderm, mesoderm, endoderm
19
Q
ectoderm becomes
A
CNS and skin
20
Q
mesoderm becomes
A
muscles
21
Q
endoderm becomes
A
insides like digestive tract and lungs
22
Q
what is neurulation
A
to develop the CNS/PNS there is a thickening of the ectoderm called the neural plate - cells migrate and proliferate to form the neural plate - notochord signals the dec of the neural plate to start happening
23
Q
what does the neural plate further develop into
A
the neural folds and neural groove - creates a trough and folds come into contract to fuse w one another
24
Q
what does the neural groove further develop into
A
neural tube and some of the cells break off to create neural crest cells (dorsal to neural tube) which becomes the PNS and meninges
25
spina bifida occurs because of
a lack of fusion of the neural tube
26
mesencephalon and rhombencephalon
spinal cord
27
prosencephalon becomes
cerebrum
28
telencephalon becomes
cerebrum... most neurons accumulating here
29
the diencephalon becomes
thalamus and third ventricle
30
cerebrum function
higher functions (cognition, language, memory)
integrates sensorimotor functions and perception
31
limbic system
regulates motivational and emotional states
32
basal ganglia
regulates motor movements and muscle tone
33
thalamus
mediates sensation to cerebral cortex
34
hypothalamus
regulates body functions such as temp, satiation, water balance, emotional behaviour, sexual response
35
cerebellum
regulates coordination of skilled movements
36
midbrain
mediates auditory and visual reflexes
maintains cortical arousal
houses cranial nerve nuclei
37
pons
houses cranial nerve nuclei
38
medulla
regulates respiration, phonation, heartbeat, blood pressure
regulates reflexes
39
how are the 2 symmetrical cerebral hemispheres organized in terms of gray and white matter?
external gray matter - cerebral cortex
internal white matter - fibre tracts (association, commissural, projection)
internal gray matter (basal ganglia, amygdala, hippocampal formation)
40
what is the cerebral cortex?
the thin rim of gray matter that covers the cerebral hemispheres - about 2-4 mm thick and contains billions of neurons
41
how many cell layers are in the cerebral cortex
6 cell layers
42
what is in layer I of the cerebral cortex
axons, glial cells
43
what is in the layer II of the cerebral cortex
many stellate and small pyramidal
44
what is in layer III of the cerebral cortex
some stellate and medium pyramidal
45
what is in layer IV of the cerebral cortex
densely packed stellate cells (sensory afferents)
46
what is in layer V of the cerebral cortex
large pyramidal cells only (motor efferents)
47
what is in layer VI of the cerebral cortex
stellate and pyramidal (back to thalamus)
48
5 lobes of the cerebral cortex
frontal, parietal, occipital, temporal, insular
49
what are the 3 main sulcus/fissure of the cerebral cortex
longitudinal fissure, central sulcus, lateral sulcus
50
what are brodmann's areas? (BA)
- Brodman examined cytoarchitecture of the cerebrum
- labelled approx 50 diff areas based on function
- can describe the function of the various regions as: primary regions, association regions (unimodal or multimodal), or limbic regions
- aka mapped the brain based on the cell layers: where it is thick w sensory cells and where is it thick with motor cells
51
pyramidal cells refer to
motor cells aka motor efferents (carry signals from brain to PNS to initiate an action)
52
stellate cells refer to
sensory cells aka sensory afferents (bring sensory info from outside world to brain)
53
what are primary areas
have a 1 to 1 correlation w sensory and motor functions
54
describe sensory primary regions
receive projections from thalamic nuclei - have a thick layer of IV (stellate cells)
55
describe motor primary regions
send projections to motor nuclei - thick layer of V (pyramidal cells)
56
what are association areas
neural signals are integrated and organized for purposeful plans
57
unimodal
integrate info related to a single modality (ex. motor planning, auditory comprehension)
58
multimodal
integrate multiple sensory inputs
59
what are the 3 sulci of the frontal lobe
lateral fissure, central sulcus, precentral sulcus
60
what are the 4 gyri of the frontal lobe
precentral gyrus, superior frontal, middle frontal, inferior frontal
61
describe the primary motor cortex (M1)
located in the frontal lobe at the precentral gyrus which is BA4 .... origin of corticospinal and corticobulbar tracts, preponderance of pyramidal (motor cells), origin of simple motor acts
62
what is the motor homunculus (somatotopic)
body is represented via the homunculus
- face, larynx, pharynx have large representation on lateral precentral gyrus
- involved in selection, preparation, initiation, and temporal sequencing of speech/mastication and other movements
63
what are the 3 unimodal association regions of the frontal lobe
premotor cortex, supplementary motor area, inferior frontal gyrus
64
premotor cortex
BA6, inferior
sensory guided movement, mirror neurons
organizing complex movements
65
supplementary motor area
BA6, Superior and medial
internally-generated movement (making a decision to move)
planning and rehearsing movements
decision making about movement (ex. tongue elevation vs tongue protrusion)
66
inferior frontal gyrus
BA 44/45
Planning and articulation of speech = Broca's area
67
what is the multimodal association region of the frontal lobe
prefrontal cortex
68
prefrontal cortex
BA 8, 9, 10, 11, 12, 46
- Converging info from brain and thalamus
- higher cog processes (attention, memory, visuospatial processes, linguistic processes)
- executive functions (inhibition, accessing memory, planning and sequencing)
69
what are the sulci of the parietal lobe
lateral sulcus, central sulcus, parieto-occipital
70
what are the gyri of the parietal lobe
postcentral gyrus, supramarginal gyrus, angular gyrus
71
what is the primary region of the parietal lobe
primary sensory cortex (S1)
72
primary sensory cortex
located at postcentral gyrus -BA 3, 1, 2
- virtual lack of pyramidal cells (layer V); Predominance of granule cells (layer IV) which receive input from thalamus
- receives contralateral somatic sensation from body regions
73
what is the sensory homunculus (somatotopic)
primary sensory cortex is mapped as a homunculus
- face, larynx, pharynx have large representation on inferior portion of postcentral gyrus
74
what is the unimodal association region of the parietal lobe
somatosensory association area (BA5,7)
75
Somatosensory association area
posterior to postcentral gyrus
- integration of sensory input to form sensory perception
76
what are the 3 multimodal association areas of the parietal lobe
parieto-temporo-occiputal region, supramarginal gyrus, angular gyrus
77
parieto-temporo-occipital region
BA39,40
- Integration of multiple sensory inputs
78
supramarginal gyrus
- at caudal border of lateral fissure
-receives auditory, visual, somatosensory info
- involved in speech, reading, writing (participates in phonological processing)
79
angular gyrus
- at caudal border of superior temporal sulcus
- receives auditory, visual, and somatosensory info
- involved in speech, reading, writing (participates in semantic processing)
80
what is the sulci of the temporal lobe
lateral sulcus
81
what are the gyri of the temporal lobe
superior temporal (BA22)
heschl's gyrus (BA41, 42)
82
what is the primary region of the temporal lobe
primary auditory cortex (A1)
83
primary auditory cortex (A1)
-heschl's gyrus (transverse temporal gyrus) - BA 41, 42
- from upper surface of the superior temporal gyrus, the transverse temporal gyrus, or Heschlls gyrus, projects medially
- distinct tonotopic (low to high freq) organization has been identified in the primary auditory cortex (Heschl's gyrus and insula)
84
what is the unimodal association area in the temporal lobe
auditory association area BA22
85
Auditory association area (BA22)
- wernicke's area
- planum temporale - posterior portion of temporal operculum (from heschel's G to the end of the lateral sulcus)
posterior half of the superior temporal gyrus
- important for language comp (receptive language processing) - applies meaning to what we hear
- auditory word recognition
86
2 sulci of the occipital lobe
parieto-occipital, calcarine sulcus
87
3 gyri of the occipital lobe
cuneus gyrus, lingula gyrus, occipital gyri
88
primary region of the occipital lobe
calcarine sulcus BA 17
89
Calcarine sulcus
primary reception area for visual input
- visual image is projceted onto calcarine sulcus (left for right), upside down
90
what is the unimodal association area for the occipital lobe
BA 18, 19, 7, 21, 20
91
BA 18, 19, 7, 21, 20
Higher level processing of visual input
pathology in this region leads to cortical blindness, visual agnosia
92
insula
hidden lobe of the cortex
- role in human emotion and behaviour (addiction, anxiety, depression)
- sensory processing
- motor planning and execution
93
describe the insula's role in sensory processing and integration
- contains neurons that are responsive to somatic, visceral, visual, gustatory, and auditory stimulation
- the seat of "subjective reality" - how you relate to what is going on in your body
- includes vestibular cortex, gustatory cortex, visceral sensory cortex, auditory association cortex
94
vestibular cortex
conscious awareness of sense of balance
95
gustatory cortex
conscious awareness of taste stimuli
96
visceral sensory cortex
conscious awareness of sensory input from thoracic and abdominal organs
97
auditory association cortex
posterior region, closest to Heschl's gyrus
98
describe the insula's role in motor programming
- swallowing = coordinates motor activity of oral musculature w taste and autonomic functions
- speech = coordination of articulatory seq, translation of phonologic code into previously learned kinematic plans, damage may lead to apraxia of speech (AOS)
99
describe the insula's role in viseceral motor activities (ANS)
involved in GI motility, cardiovascular responses, respiration, salivatory responses (ex. damage can lead to cardiac abnormalities including arrhythmias and even sudden cardiac death)
100
within the telencephalon (internal white matter), what 3 types of fibre tracts travel beneath the cortex
association tracts, commissural tracts, projection tracts
101
what is the finger trick for the 3 internal white matter fibre tracts
association = pointer fingers
commissural = middle fingers
projection = thumbs
102
association fibres
connect cortical areas w/i a hemisphere
103
2 types of association fibres
short fibres and long fibres
104
short association fibres
- connect primary areas to unimodal association areas w/i a cortical lobe (take info from primary to association)
- lesions to primary sensorimotor areas can result in degeneration in the association areas due to lack of info sharing
105
long association fibres
connect more distant cortical regions across cortical lobes
106
arcuate fasciculus
extends from wernicke's area to broca's area (language comprehension/langauge programming to motor programming) - hears something which goes to temporal lobe, now need to respond which sends it to broca's area so that we know what to say
107
commissural fibres
- corpus callosum and 2 smaller pathways (anterior commissure and posterior commisure) connect the 2 cortical hemispheres
- other non-cortical structures are also connected by commissural fibres (ex. thalamus and hippocampus)
108
corpus callosum
- commissural fibres
- connection bw the hemispheres (takes info from same place on one side to same place on other side)
- comprised of at least 200 mill fibres
- fibres of corpus callosum are primarily homolateral - travel bw homologous loci in the 2 hemispheres (ex. auditory cortex in primates has mostly homolateral projections; the fibres are often referred to as the transcollasal auditory pathway)
-
109
projection fibres
connect regions of cerebral cortex to lower parts of the CNs (ex. thalamus, brainstem, spinal cord)
110
all projection fibres entering/exiting the cortex come together as the?
internal capsule - travelling bw the nuclei of the basal ganglia (both afferent and efferent fibres)
111
the pathway of sensory projection fibres for audition is
medial geniculate body (thalamus) sends projection fibres to Heschl's gyrus (A1)
112
the pathway of sensory projection fibres for touch/pressure is
from thalamus to S1 in postcentral gyrus
113
the pathway of motor projection fibres is
cortical motor fibres from M1 descend the pyramidal tract
114
Within the telencephalon's internal gray matter (deep gray matter), what are the 3 subcortical regions?
Basal ganglia, amygdala, hippocampal formation
115
what are the 3 structures the basal ganglia is comprised of
caudate nucleus, putamen, globus pallidus
116
globus pallidus
w/i basal ganglia - nuclei participate in control of body posture and muscle tone, and planning/initiating movements
117
what are the 2 functional units of the basal ganglia
substantia nigra and subthalamic nucleus
118
what do the substania nigra and subthalamic nucleus do?
- both areas function like the basal ganglia (v connected) and act like the BG
- Substantia N - axons from SN in midbrain terminate in caudate N and putamen
- Subthalamic N - axons from subthalamic N innterconnect w globus pallidus
119
how is parkinsons related to the basal ganglia
motor disease of the BG - difficulty planning/initiating/terminating movement - but often BG has no pathology - instead pathology in substantia nigra - SN causes BG to dysfunction
120
how does the basal ganglia communicate w the cortex
communicates extensively w the cortex: receives input from many cortical regions, and all output is sent back to motor cortex, via the thalamus
121
Basal ganglia's major functions
assist in regulating initiation and termination of movements, regulating intensity - also controls subconscious contractions of muscles (ex. arm swinging w walking) - also involved in initiating and terminating cog processes (attention, memory, planning) .... may work w limbic sys to regulate emotional behaviour (OCD)
122
limbic system
functional brain system comprised of a group of structures on the medial aspect of the cerebral hemispheres - connects to cortex so that we can regulate our emotions (especially connected to frontal cortex)
"emotional brain"
123
what structures does the limbic sys include
cingulate gyrus, parahippocampal gyrus, amygdala, hippocampal formation
124
amygdala
a part of the limbic system, involved in processing and responding to fear, forms and retrieves memories based on emotional impact
125
hippocampal formation aka hippocampus
encodes, consolidates, retrieves memories of facts and events
