Neurology Flashcards
1
Q
What makes up the brainstem
A
the medulla oblongata
the pons
and the midbrain
2
Q
How many cranial nerves are there
A
12 pairs
3
Q
How many spinal nerves are there
A
31 pairs
4
Q
What does the diencephalon compose of
A
the thalamus and hypothalamus
5
Q
what does the cerebrum compose of
A
cortex, amygdala, hippocampus, basal ganglia and white matter
6
Q
What does the medulla oblongata do/have
A
cardiovascular and respiratory control
nuclei that relay information about taste
hearing and balance
control of neck and facial muscles
7
Q
What does the pons do/have (just name a couple)
A
Controls: respiration, sleep, taste, bladder control, hearing, swallowing, eye and facial movements, posture, facial sensation
8
Q
What does the midbrain do
A
components of auditory and visual systems
9
Q
What is the cerebellum involved in
A
maintaining posture, coordinating head movements, fine-tuning movements, and motor learning
10
Q
What is the thalamus essential for
A
transfer of all sensory information (except olfactory)
11
Q
what else is the thalamus for
A
gates and modulates sensory information
Involved in integration of motor control
influences attention and consciousness
12
Q
What does the hypothalamus do
A
regulates homeostasis and behaviours necessary for sexual reproduction
13
Q
What are the higher functions of the cerebrum
A
perception, motor planning, cognition, emotion and memory
14
Q
What does the amygdala do/where is it located
A
involved in social behaviour and emotion
located beneath the cortex
15
Q
What does the hippocampus do/where is it located
A
involved in memory
located beneath the temporal lobe
16
Q
What is white matter
A
axons that carry information to and from the cortex between structures
17
Q
What are sulci
A
grooves in the brain
18
Q
What is a gyrus
A
Raised areas between sulk (grooves)
19
Q
What does the autonomic nervous system compose of
A
parasympathetic and sympathetic nervous system which innervate visceral organs
20
Q
What do the anterior cerebral arteries supply
A
motor and sensory cortex of the lower limb
21
Q
What do the middle cerebral arteries supply
A
the motor and sensory cortex of the upper limb, face and auditory cortex
22
Q
What do the posterior cerebral arteries supply
A
the whole of the visual cortex
23
Q
What is a watershed infarct
A
a localized area of ischemic tissue death in an area of the brain situated at the farthest point of blood supply from two separate cerebral arterial systems that is caused by inadequate blood flow
24
Q
Main symptoms of a stroke
A
F -face (may have drooped to one side)
A- arms (may not be able to lift them above their head due to weakness or numbness)
S- speech (slurred, garbled or unable to talk despite being conscious)
T- time (dial 999)
25
Where is the most common site for ischaemic stroke
middle cerebral artery
26
What happens if autoregulation of blood volume is too low in the brain
cerebral blood flow decreases and there is ischemic damage
27
Define ischaemic
deficient supply of blood to a body part
28
What happens if there is an increase of auto regulation of blood flow to the brain
```
intracranial pressure increases
oedema and crushing brain tissue
shifting of brain structures
restriction of blood flow
herniation
```
29
What does glutamate act on and what does it do
acts on astrocytes, which increases calcium and activates nitric oxide synthase which releases nitrogen oxide and the vessels dilate
30
What contrasting agent can be used with fMRIs
gadolinium
31
What are the three sections of the brain
prosencephalon
mesencephalon
rhombencephalon
32
What does the prosencephalon compose of
cerebrum/cerebral hemispheres (telencephalon)
| and thalamus and hypothalamus (diencephalon)
33
What does the mesencephalon compose of
the midbrain
34
What does the rhombencephalon compose of
pons and cerebellum (metencephalon)
| And the medulla (myelencephalon)
35
When does the nervous system start developing
3rd week in utero
36
What does the nervous system develop form
the ectodermal layer
37
How does the nervous system develop
neural groove develops in midline
neural cells proliferate and form neural tube
neural tube forms adult spinal cord and at the cephalic (head) end it swells and flexes to form the brain
38
What happens in the third month of development of the spinal cord
spinal cord extends the entire length of the embryo and spinal nerves pass through the intervertebral foramina at their level of region
39
What happens to the spinal cord with increasing age from development
vertebral column and dura mater lengthen more rapidly than the neural tube, and the terminal end of the spinal cord shifts to a higher level (at birth this is the level of the third cervical vertebra)
40
In an adult where does the spinal cord terminate
At the level of L2 to L3, the dural sac and subarachnoid space extend until S2
41
When does the brain double in size
within the first year of life
42
True/false: at birth you have all the neurones you will ever need
true
43
When is the brain at 80% of its full adult volume
age 3
44
When does the brain have twice as many synapses as it will ever have
at age 2/3
45
What are the three meninges that surround the brain
the dura mater, arachnoid mater and pia mater
46
Describe the dura mater
thickest, outermost meninges that consists of two layers (superficial and deep)
layers are close together except for areas where meningeal layers dip down into brain fissures
47
Describe the superficial dura mater
Called the endosteal (periosteal) layer
| not continuous with the dura of the spinal cord
48
Describe the deep dura mater
called the dura mater proper
| is continuous with the dura of the spinal cord
49
What is the falx cerebri
vertical fold lying in the midline between the two hemispheres (in longitudinal fissure)
50
What is the tentorium cerebelli
Fold lying above the cerebellum and below the cerebrum
roofs over the posterior cranial fossa
has an opening (tentorial notch) which allows the midbrain to pass through
51
What kind of problems can arise from space occupying lesions (think tentorium cerebelli)
as the dura is tough and immovable the brain may be pressed against or herniate through the tentorial notch
52
Describe the arachnoid mater
Middle layer of meninges
Separated from dura mater by subdural space (filled by film or fluid)
Separated from Pia mater by subarachnoid space (filled with cerebrospinal fluid)
It bridges over sulci
53
Describe arachnoid villi
Part of the arachnoid mater where it projects through dura into venous sinus spaces
Collections of them form arachnoid granulations along sinuses
They are one-way valves which allows CSF to drain into venous sinuses and into the venous system
54
Describe the pia mater
Thinnest and innermost layer
closely follows brain structures, extends down into sulci
cerebral arteries that enter the brain have a covering of pia mater
55
What else lies in the subarachnoid space
blood vessels and cranial nerves
56
What causes a headache (think meninges)
(brain itself has no pain receptors)
| stretching and irritation of meninges or blood vessels cause headaches
57
Describe bacterial meningitis
Inflammation due to streptococcus pneumoniae and neisseria meningitides
Immune response leads to cerebral oedema (build up of fluid) and increase in internal pressure (lead to herniation and reduced. blood flow)
Definitive diagnosis by CSF examination (lumbar puncture) - high white cells, high protein and low glucose
58
Total volume of CSF and what's in ventricles
total ~150ml
| ventricles ~25 ml
59
Amount of CSF produced daily
around 500ml daily
60
Describe CSF
```
it is an ultra filtrate of blood
active secretion by the choroid plexus
Removes waste products
transports signalling molecules
supports, cushions and evenly distributes pressure on the brain
```
61
What is the choroid plexus
network of capillaries separated from ventricles by choroid epithelial cells
CP in lateral ventricles is continuous with CP in 3rd ventricles
62
What is hydrocephalus
build up of CSF in the brain
causes an increase in intracranial pressure
can be fatal
63
How can the stretch reflex in the calf be elicited
by tapping the achilles tendon with a reflex hammer
64
What does the simplest reflex pathway involve
involves only one synaptic relay in the spinal cord (called monosynaptic reflex) so response latency is short
65
What kind of information do ascending tracts of the somatosensory pathway carry
from thermal, pain, tactile, muscle and joint receptors to the cerebral cortex (Conscious centre)or the cerebellum and brainstem (unconscious centre)
66
Three types of peripheral receptors
unencapsulated/free nerve endings
Modified/encapsulated endings
Proprioceptors
67
Give three examples of unencapsulated peripheral receptors and what information do they carry
Merkel's discs, hair follicles, nociceptors
| pain, temperature and pressure
68
Give three examples of encapsulated peripheral receptors and what information they carry
Mesiner's corpuscles, Pacinian corpuscles, Ruffini endings
| Pressure, touch, vibration, stretch, pain, proprioception
69
Give three examples of proprioceptor peripheral receptors and what information they carry
Muscle spindles, Golgi tendon organ, joint kinaesthetic receptors
pain, Stretch , pressure
70
What is the dorsal medial lemniscus pathway
three-neuron pathway
pathway for fine touch and proprioception
is an ascending tract
71
Describe the pathway of the dorsal medial lemniscus pathway
First order neuron ascends the spinal cord via the cuneate fasciculus (upper limb) or gracile fasciculus (lower limb) before synapsing in the cuneate or gracile nucleus within the medulla oblongata
Second order neurones decussates here and ascends via the medial lemniscus to the thalamus
Third order neuron ascends via the internal capsule to synapse in the primary somatosensory cortex
72
Describe the thalamus
located either side of the third ventricle
receives information via second order neurones
Contains multiple nuclei
integrates, modulates and relays information
73
What are polymodal nociceptors
respond to many different stimuli(including tissue damage)
C fibre afferents
slow pain
74
What are mechanical nociceptors
activated by high pressure
fast conducting fibres
A fibres
Sharp pain
75
What are thermal nociceptors
respond to extreme heat or cold
76
What are the two classes of nociceptor fibres
A𝛿 (delta)
| C-fibres
77
Describe A𝛿 fibres (think nociceptor)
small diameter, myelinated
nociceptive specific : thermal or mechanical nociceptors
Fast, sharp, well-localised pain
78
Describe C fibres (think nociceptor)
non-myelinated
nociceptive specifice: polymodoal
dull, aching, burning pain
79
What are the three indirect tracts of the anterolateral system
spinoreticular tract
spinocerebellar tract
spinotetcal tract
80
What are the two direct tract of the anterolateral system
anterior spinothalamic tract
| lateral spinotahalamic tract
81
Describe what information the anterior spinothalamic tract carries
crude touch and pressure
82
Describe what information the lateral spinothalamic tract carries
pain and temperature
83
Generally describe the spinothalamic tract
conveys pain, temperature and crude touch
| fast sharp pain (A𝛿 fibres) and dull ache (C-fibres)
84
Generally describe the indirect pathways of the anterolateral system
modulate pain and can terminate in other brain regions
85
Describe the pathway of spino-reticular tract
goes through reticular formation and to the cortex
86
Describe the pathway of the spino-cerebellar tract
goes through cerebellar peduncles and to cerebellum
87
Describe the spinotectal tract
orientates eyes and head towards stimuli
88
Describe the pathway of the spinothalamic tract
First order neurones ascend/descend 1-2 spinal levels through Lissauer's tract before synapsing in the substantia gelatinosa at the tip of the dorsal horn
Second order neurones decussate and ascend to the thalamus via the anterior (Crude touch) or lateral (pain and temperature) spinothalamic tract
Third order neurones through internal capsule to the primary somatosensory cortex
89
What is somatic sensation of the face mostly supplied by and what is additional sensation provided by
the trigeminal nerves
| additional: facial, glossopharyngeal and vagus nerves
90
Describe the sensory inputs to the head pathway
synapse onto second-order neurones in the ipsilateral trigeminal nucleus
axons decussate and project in the trigeminal lemniscus to the ventral posterior medial nucleus of the thalamus
fibres project onto the sensory cortex (parietal lobe)
91
Three sensory nuclei of the trigeminal nerve
principle sensory nucleus
spinal nucleus
mesencephalic nucleus
92
Describe the principle sensory nucleus of the trigeminal nerve
senses touch, conscious proprioception, and pressure
93
Describe the spinal nucleus of the trigeminal nerve
senses pain and temperature
94
Describe mesencephalic nucleus of the trigeminal nerve
non-conscious proprioceptive information
95
Describe the motor nucleus of the trigeminal nerve
innervates the muscles of mastication
96
Describe the generation of voluntary movements
1) Identify target/goal (visually identified in retinotopic space)
2) Locate it in external space (visually identify in retinotopic space)
3) Determine limb trajectory (Internal representation of arm/hand relative to object)
4) calculate the forces necessary to generate desired trajectory (muscle-based reference frame)
97
Describe why cortical regions are involved in motor cortex
to plan, control and execute movements
98
What is the motor homunculus
somatotropic map of the primary motor cortex
99
What is the primary motor cortex
region where movement can be evoked with the least amount of electrical stimulus
100
Where is the primary motor cortex located
on the pre-central gyrus (Brodmann's area 4)
101
What is an error signal
difference between desired and actual position
102
What is feedforward control
sensory information gives advanced control
anticipation of the required movement
enables movement to be the direction of target
103
What are the medial descending pathways
```
Anterior corticospinal tract
tectospinal tract
medial reticulospinal tract
lateral vestibulospinal tract
Medial vestibulospinal tract
```
104
What are the lateral descending pathways
Lateral corticospinal tract
| lateral reticulospinal tracts
105
describe the medial descending pathways generally
Controls axial muscles for posture and balance
| controls anti-gravity muscles
106
Describe the lateral descending pathways generally
controls both proximal and distal muscles
| responsible for most voluntary movements of the limbs
107
Describe the corticospinal tract
controls muscles of distal limbs and trunk
essential for fine motor movements
longest and largest descending CNS tract
108
Describe the pathway of the descending corticospinal tract
first order neurones descends from the primary motor cortex via the internal capsule
then enters brainstem via crus cerebri
75-90% fibres decussate at the pyramids in the medulla oblongata before exiting the spinal cord via the ventral root
those that decussate descend down the lateral corticospinal tract
those that don't (10-15%) descend ipsilaterally down the ventral/anterior corticospinal tract
109
Describe the function of the lateral corticospinal tract
controls muscles of distal limbs
responsible for most voluntary movements of limbs
fine movement of contralateral limbs (limbs pertaining to the other side)
110
Describe the function of the anterior corticospinal tract
controls trunk muscles
| responsible for maintaining posture
111
Another name of corticonuclear tract
corticobulbar tract
112
Describe the corticonuclear(bulbar) tract
originates in the motor cortex
terminates in the brainstem nuclei
innervates cranial nerves
113
What nuclei of cranial nerves don't receive bilateral innervation from the cortex
```
facial motor nucleus (controlling facial muscles below the eye)
hypoglossal nucleus (controlling tongue movements)
```
114
Three additional motor pathways (extrapyramidal pathways)
rubrospinal tract
vestibulospinal tract
tectospinal tract
115
Describe the rubrospinal tract
originates in red nucleus in brainstem
exact function is unknown
responsible for regulation of flexor muscles (upper limb flexion)
116
Describe the vestibulospinal tract
originates in vestibular nucleus
controls muscles of neck, trunk and some leg muscles
maintains upright posture and head stabilisation
117
Describe the tectospinal tract
Originates in superior colliculus in midbrain
information from eyes and visual cortex
innervates contralateral motor neurones controlling head position
118
Generally describe the reticulospinal tract
originates from reticular formation (pons and medulla)
Innervates interneurons affecting corticospinal tract
Damage can lead to spasticity (continuous contractions)
119
Describe the pontine reticulospinal tract
ipsilateral innervation of extensor motor neurones
120
Describe the medullary reticulospinal tract
bilateral innervation of flexor motor neurone
121
What do the levels of damage to motor pathways dictate
severity of symptoms
| higher levels shows increased percentage of motor with motor deficits
122
Describe some symptoms of upper motor neurone damage
```
paralysis of movement
increased muscle tone
hyperactive stretch reflex
extensors plantar reflex (babinski sign - sharp object dragged across bottom of foot and toes flare up instead of down)
Reduction in superficial reflexes
```
123
Describe some symptoms of lower motor neurone damage
paralysis of muscle
hypotonia
atrophy of muscles
fasciculations (spontaneous contractions) and fibrillations
loss of stretch reflex but superficial reflexes remain intact
124
Briefly describe the cerebellum
Part of the hindbrain (sits in posterior fossa)
Below cerebrum (separated by tentorium cerebelli)
Connected to brainstem via cerebellar peduncles
Cerebellar cortex - gray matter (folia
cerebellar pathways - white matter tracts
125
Describe cerebellum anatomy
Left and right hemispheres joined by median vermis
divided into anterior and posterior lobe by primary fissure
flocculonodular lobe sits behind brainstem (most primitive lobe)
Cerebellar tonsils sit below foramen magnum
126
Describe cerebellar function
co-ordinates movement on ipsilateral side
monitors & initiates voluntary movement through manipulation of fine muscle movement
partly responsible for learning motor skills
Receives somatosensory and proprioceptive info from entire body
(including visual, auditory and vestibular info)
127
What are the three inputs via the inferior cerebellar peduncles for information into the cerebellum
```
Spinal cord (spinocerebllar ascending tracts -> anterior lobe and vermis)
Vestibular nuclei (vestibulocerebellar tract -> anterior lobe and vermis)
Inferior olive (olivocerebellar tract -> cerebellar hemispheres)
```
128
What are the inputs via the middle cerebellar peduncle for information into the cerebellum
sensory/motor information -> pontine nuclei -> cerebellar cortex
129
What are purkinje cells
inhibitory cells and so have an inhibitory action on the cells they synapse onto
130
Describe purkinje cells
Large output neuron in cerebellar cortex
triangular cell body, single long axon
numerous branching dendrites
131
What doe purkinje cells release
GABA (gamma aminobutyric acid) (inhibitory neurotransmitter)
| it regulates and co-ordinates movement
132
What are the three cell layers of the cerebellar cortex
outer synaptic/receptive layer (molecular layer)
Intermediate discharge layer (Purkinje cell layer)
inner receptive layer (granule cell layer)
133
What five cell types do the layers of the cerebellar cortex contain
```
purkinje cells
granule cells
basket cells
stellate cells
Golgi cells
```
134
What is the mossy fibre circuitry
feedforward control
| gives appropriate movement
135
What is the climbing fibre circuitry
feedback control
| for error correction
136
True/false: cerebellar cortex has an output directly to the spinal cord
false
137
Describe the pathway for pre-programming movements from the cerebellum
lateral hemispheric cortex -> dentate nucleus -> superior peduncle -> cerebral cortex (via thalamus)
138
Describe the two pathways for motor execution from the cerebellum
1) paravernal cortex -> globose & emboli form nucleus -> superior peduncle -> red nucleus -> lateral descending pathways
2) vermis -> fastigial nucleus -> inferior peduncle -> medial descending pathways
139
What are the 6 signs of cerebellar damage
impaired motor function on ipsilateral side of the body
ataxia (slow and uncoordinated voluntary movements)
intention tremor (uncoordinated, jerky movements, overshoot dysmetria)
Dysdiadochokinesis (inability to perform rapidly alternating movements)
hypotonia (reduced tone in muscles)
nystagmus (jerky eye movements)
140
What is ataxia
slow and uncoordinated voluntary movements
141
What is intention tremor
uncoordinated, jerky movements
| overshoot dysmetria
142
What is dysdiadochokinesis
inability to perform rapidly alternating movements
143
What is hypotonia?
reduced tone in muscles
144
what is nystagmus
jerky eye movements
145
6 components of the basal nuclei
```
caudate nucleus
putamen
globus pallidus
subthalamic nucleus
substantia nigra
nucleus accumbens
```
146
What is the main function of the basal nuclei
initiation and control of voluntary movements
147
What are some other functions of the basal nuclei
eye movements
learning routine behaviours
emotional and behavioural responses
148
Briefly describe the direct pathway that allows movements to occur (basal nuclei)
activation leads to removal of inhibitory input to thalamus
leads to excitation of motor cortex
which facilitates wanted movement
149
Briefly describe the indirect pathways that inhibits unwanted movements (basal nuclei)
Activation enhances inhibitory input to thalamus
| no excitation of cortex - inhibits unwanted moves
150
Describe what actually happens in the direct pathway involving basal nuclei
Uses GABAergic striatal neurons (D1)
motor cortex sends excitatory signals to the striatum via the corticostriatal pathway
inhibitory GABAergic neurones from the striatum send their axons to the medial globus pallidus and substantia nigra
Their axons are then sent to the thalamus (also inhibitory)
this causes disinhibition
which is an increased thalamic output to cerebral cortex which facilitates wanted movements
151
Describe what actually happens in the indirect pathway involving basal nuclei
Uses GABAergic striatal neurones (D2)
Begins from the cortex projecting to the striatum
then axons are projected to the external globus pallidus
Neurones from GPe (external globus pallidus) send inhibitory fibres to sub thalamic nucleus
From there neurones are sent to the internal globus pallidus (GPi) and substantia nigra (SNr)
Then continue as a direct pathway with GABAergic inhibitory neurones to the thalamus and glutamate excitatory efferents to the cortex
152
Describe the nigrostriatal pathway
largest dopaminergic pathway in the brain
originates in the substantia nigra pars compacta (SNpc)
enhances activation of D1 neurones (direct pathway)
Suppresses activation of of D2 neurones (indirect pathway)
153
Two main disorders of the basal nuclei
parkinson's disease
| Huntington's disease
154
Describe Parkinson's disease
loss of substantia nigra pars compacta dopamine neurones
excessive inhibition of (GPe) external globus pallidus which means increased inhibition of the thalamus
Have trouble initiating willed movement
155
Signs/symptoms of Parkinson's disease
bradykinesia = slowness of movement
akinesia = difficulty in initiating voluntary movement
rigidity = increased muscle tone, stiffness
Resting tremors of hand and jaw
cognitive deficits, depression, sleep disorders
156
Describe Huntington's disease
autosomal dominant progressive neurodegenerative disease
loss of striatal neurones in the indirect pathway
decreased inhibition of the thalamus and subsequent loss of cortical neurones
failure to suppress unwanted movements
157
Signs/symptoms of Huntingon's disease
hyperkinesia and dyskinesia (abnormal movements)
chorea - spontaneous, irregular jerky movements
Dementia
changes in mood and personality
death
158
What does the left lateral temporal lobe
speech comprehension
159
What does the right lateral temporal lobe do
memory for sounds, shapes and faces
160
What is neglect of occipital or parietal lobe
when someone ignores half of space, usually the left space
| such as missing half a plate of food or not noticing someone on the left
161
What is hemianopia
visual loss in one half of space
162
What is dyspraxia
difficulty carrying out practical tasks (dressing, washing)
163
four main reasons for cognitive decline
acute illness (delirium)
fatigue including sleep disorders
metabolic disorders (thyroid/liver disease, vitamin deficiency (B1))
Dementia
164
What are the four main types of dementia
alzhiemers
vascular
Lewy body
frontotemporal
165
What is Wernicke encephalopathy
```
acute sever deficiency of thiamine
common symptoms:
ocular abnormalities
mental status change
incoordination of gait and trunk ataxia
```
166
What is Korsakoff's syndrome
chronic neurological sequelae of thiamine deficiency
alcohol related brain disease
behavioural and cognitive change -amnesia
167
What is dry Beri Beri
B1 deficiency with nervous system involvement
peripheral nervous damage
(numb, weak leg/arms)
168
What is stress
a physical chemical or emotional factor that causes bodily or mental tension
or a state resulting from stress
169
What are the limbic system centres
```
amygdala
hippocampus
septal nuclei and nuclei accumbens
olfactory bulbs
hypothalamus
cingulate and anterior cingulate gyrus
orbitofrontal cortex
```
170
Amygdala function in limbic system
episodic memory
| emotion matching
171
Hippocampus function in limbic system
memory and learning, especially spacial
172
Septal nuclei and nuclei accumbens function in limbic system
pleasure/reward
173
Hypothalamus function in limbic system
hormonal response
174
orbitofrontal cortex function in limbic system
decision making
| consciousness
175
What does the limbic system do? generally
provides an emotional guidance system based on past experiences
stores information connected with past experiences to compare to current circumstances
176
What is allostasis
process of maintaining homeostasis through the adaptive change of the organisms environment to meet perceived and anticipated demands
177
Describe what happens in a chronic threat/defence (stress) response
increased threat monitoring in the amygdala, increased size
reproduction in quantity and complexity in the hippocampus
sensitisation of the CNS to painful stimuli
178
What is the CNS response to increased vagal tone
Counteract HPA axis and SNS
increased seratonin
calming affects on limbic system , amygdala
increased new nerve cells and connectivity in hippocampus
general inhibitor effect in brainstem centres
179
Describe the threat/defence response in terms of breathing
happens via mouth
upper chest breathing
the in breath is more than the out breath
oxygen overload whereas carbon dioxide is abnormally low
this is good for physical exertion
if prolonged it can lead to chronic hyperventilation states
180
Describe the rest/restore response in terms of breathing
happens via nose
diaphragmatic breathing
smooth even breath
In breath less than out breath
181
Name some of oxytocin's wider actions
promotion of cell division and wound healing
reduced anxiety, increased curiosity to learn
increased maternal caring and protective behaviours
increased trust, social interaction and social memory
lower pain threshold
promotion of sexual activity
182
Definition of a reflex
simple, stereotyped response that couples sensory input to motor input
183
What are involuntary movements evoked from
periphery stimulation coupling sensory input to motor input
184
Describe involuntary movements on peripheral neurones
from receptors in periphery to spinal cord or brain stem
| they innervate ⍺-motor neurones and 𝛄 motor neurones and interneurones in the brainstem or spinal cord
185
Describe role/pathway of lower motor neurones on involuntary movements
pathway: from brainstem or spinal cord to muscle/periphery
| stimulate or inhibit contraction via neuromuscular junction
186
Significance of divergence on reflexes
amplifies sensory input and coordinates muscle contractions for movement
187
Significance of convergence on reflexes
on internerons increases flexibility of response
188
What are proprioceptors
specialised muscle cells that detect stretch
189
What is a myostatic reflex
one of the simplest reflex
| only has one synapse
190
What does a myostatic reflex prevent
overstretch of a muscle
191
What is a myostatic reflex tested by
tapping tendon
192
Describe reflex pathway physiology
```
weight added/tap of tendon
muscle stretch
AP firing in afferent neuron
AP firing in efferent neuron
muscle shortens
```
193
What is a polysynaptic reflex
two (or more) synapses
stimulus is a muscle stretch
inhibitory interneurons synapse onto another alpha motor neuron
194
Describe gamma motor neurones
```
smaller neurones (up to 35mm)
innervate specialised striated muscle (intrafusal muscle fibres)
adjust sensitivity of muscle spindles and increase range of function
```
195
Describe Golgi tendon organs (proprioceptors)
sensory neurones in tendon encode information on muscle tension and contraction
196
What do Golgi tendon organs do
monitor and maintain muscle tension
| inhibit further contraction
197
Describe the Golgi tendon reflex that prevents overstretch of tendon
```
muscle contraction stretches tendon
sensory neurons (Ib afferents) activate interneurons
inhibit ⍺-neurones innervating muscle of origin
opposite of myostatic reflex
```
198
Describe how Golgi tendon reflex controls muscle tension
inhibits muscle contraction
protects muscle from causing damage to tendon
fine control of tension for grasping fragile obects
199
What are the 3 different sources of input for alpha motor neurones
sensory input from muscles
descending input from upper motor neurones (initiating and controlling voluntary movement)
interneurones (excitatory or inhibitory) form neuronal circuits that produce coordinated movement
200
What are the two reflexes tested in a neurological exam
patellar tendon reflex (L3) and ankle jerk reflex (S1)
201
What does weak or absent reflex mean
possible lower motor neurone lesion
202
What does exaggerated reflex mean
possible upper motor neurone lesion
203
What does Jendrassicks manoeuvre do
heightens lower limb tendon reflexes
204
Name two additional cutaneous reflexes
flexion withdrawal reflex and crossed extensor reflex
205
Describe the flexion withdrawal reflex
rapidly removing limb from harmful (noxious) stimuli
cutaneous receptors in skin
activation of primary afferent neurones (flexor reflex afferents)
disynaptic reflex: inhibitory interneurons excite flexor motor neurones and inhibit extensor motor neurones
206
Describe crossed extensor reflex
maintains balance during flexion withdrawal reflex
| simultaneous extension of contralateral limb
207
Name the four brainstem reflexes
jaw reflexes
eye reflexes
throat reflexes
postural reflexes
208
Describe the jaw jerk reflex
downward tap on the jaw stretches the muscle
activation of the trigeminal nerve (CNV)
contraction of the masseter muscle
209
Describe the jaw unload reflex
initiated by sudden unloading of the jaw
activation of the trigeminal nerve (CNV)
inhibition and activation of jaw muscles
stops jaw movement, protects teeth
210
What are the three visual reflexes
pupillary light reflex
accommodation reflex
corneal (blink) reflex
211
Describe the pupillary light reflex
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pupil constriction (both eyes) in response to light
activation of optic nerve (CNII) constriction via oculomotor nerve (CNIII)
protection = adaptation to light levels
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212
Describe the accommodation reflex
adduction of the eye initiated by change in focus
activation of optic nerve (CNII) change in lens shape by oculomotor nerve (CNIII)
protection = prevents blurred vision
213
Describe the corneal (blink) reflex
closure of both eyes initiated by foreign object touching eye
activation of trigeminal nerve (CNV) innervates eyelid via facial nerve (CNVII)
protective: protects eyes from foreign object
214
What are two throat reflexes
gag reflex
| swallowing reflex
215
Describe the gag reflex
initiated by object touching the posterior wall of pharynx
activation of glossopharyngeal nerve (CNIX)
contraction of soft palate and pharynx
216
Describe the swallowing reflex
initiated by food bolus created by chewing
causes closure of glottis, elevation of larynx, and transient cessation of respiration
protects the airway
217
What are the postural reflexes
tectospinal and vestibulospinal reflex
218
Describe the tectospinal and vestibulospinal reflex
initiated by visual or auditory stimuli
coordinates head and eye movements, maintains posture
protective: responsive to changes in surrounding environments
219
How does stress affect the immune system
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increases risk of disease
reduces wound healing
reduces immune system
increases perception of pain
some symptoms are innately stressful
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