Theme 2 - Sensory Inputs and Motor Outputs Flashcards
An ipsilateral lesion to the dorsal medial leminscus tract spinal cord (for example in MS) will result in what?
loss of propriception on the same side
What is a loss of coordination and balance without visual cues known as?
sensory ataxia
What is the test/sign for sensory ataxia?
Rombnerg’s sign - severe swaying on standing with eyes closed and feet together
An ipsilateral lesion to the white matter anterolateral column will result in what?
Loss of pain, temperature and crude touch on opposite side
What will an ipsilateral lesion to the posterior spinocerebellar tract cause?
Loss of lower limb muscle coordination on the same side
3 symptoms associated with upper motor neuron disease
Spastic paralysis
Overactive tendon reflexes
No significant atrophy
If there is a degeneration of upper motor neurons above the pyramids which side will it mainly affect?
opposite side
Three features of lower motor neuron disease
Flaccid paralysis
No tendon reflexes
Atrophy
What does amyotrophic lateral sclerosis (Lou Gehrigs disease) affect?
progressively and selectively affects both lower and upper motor neurons
What three things will be affected in anterior cord syndrome?
Bilateral lower motor paralysis and atrophy (lower motor neurons
Bilateral spastic paralysis descending anterior tracts
Loss of pain, temperature and fine touch
What sensation remain intact during anterior cord syndrome
proprioception
tactile descrimination
vibration
5 effects of Brown-Sequard hemisection?
ipsilateral paralysis and atrophy (lower motor)
ipsilateral spastic paralysis (upper motor)
ipsilateral anesthesia at lesion level (dorsal root)
ipsilateral loss of proprioception
contralateral loss of pain, temp and light touch
4 Effects of complete cord transection
Complete loss of sensation and voluntayy movement below transection site
Bilateral lower motor neuron paralysis and atrophy
Bilateral spastic paralysis
Bladder and bowel non voluntary
Outline the motor control hierarchy in terms of associated areas of the brain (high to low)
Association areas of neocortex, basal ganglia
Motor cortex/cerebellum
Brainstem/spinal cord
What are the 5 descending motor pathways?
Corticospinal Rubrospinal Reticulospinal Tectospinal Vestibulospinal
Where does the corticospinal tract begin, dessucate and synapse?
Motor cortex
Medullary pyramids
Lateral CS tract
Where does the Rubrospinal tract begin, dessucate and predominantly end up?
Red nuclei in midbrain
Medulla
Cervical junction
Where does the vestibular spinal tract begin and where do they go?
Medial and Lateral vestibular nucleus in brainstem
Med - neck muscles
Lateral - Limbs
What does the vestibular muscles facilitate?
Keeping a steady gaze
Steady balance and posture
From where does the Tectospinal tract originate?
Superior and inferior colliculi
What does the tectospinal tract from each collucili help you to do?
Superior collucili - instant neck and head muscle responce to fast visual stimulus
Where does the reticulospinal tract originate and what is it associated with?
Reticilum (back) of brainstem and aid with posture
What descending pathways are associated with control of head and neck movements?
Tectospinal and medial vestibulospinal
What descending pathways are associated with control of limb extension?
Lateral vestibulospinal and reticulospinal
What descending pathway is associated with flexion of upper limbs?
Rubrospinal
In a coma pt, what type of posturing will result in them flexing their arm and either flexing or extending their leg?
decorticate posturing
In a coma pt what type of posturing will result in them extending both their arms and legs?
decerebrate
What indication do decorticate and decerebrate posturing give about the location of the lesion?
decorticate - above red nucleus (Rubrospinal tract intact)
decerebrate - below red nucleus
Does the babinski reflex indiacate an upper or power motor neuron lesion?
Upper
Where does the corticobulbar pathway go from/to?
motor cortex to cranial nerves
What is the difference in terms of lesion localisation and facial palsy between a stroke and Bells palsy?
Stroke - upper motor neurone, contralateral lower half
Bell’s - lower motor neurone, ipsilateral, full half
What is abulia?
Loss or impairment of the ability to make decisions or act independently
A stroke associated with what type of artery is most likely to result in abulia?
Anterior cerebral
What type of seizure is associated with a “march” of symptoms?
Jacksonian
What can damage to the posterior parietal cortex result in?
neglect - can perceive but not attend
What pathways are associated with the posterior parietal cortex?
somatosensory afferent
visual afferent
Damaged to the interconnections between the sensory and motor coordination areas is likely to result in what?
Apraxia
What term describes a difficulty in sequencing and execution of movements?
Apraxia
Aphagia
Anosia
Apraxia
What is the difference between ideational and ideomotor apraxia and what areas of the brain are they assocoated with?
Ideational (parietal) cannot report sequence
Ideomotor (SMA) - cannot use the tool
What condition is best described as sustained muscle contractions, usually producing twisting and repetitive movements or abnormal postures or positions.
If only occurs with certain actions, said to be ‘task specific’.
dystonia
3 functions of the cerebellum
Maintenance of balance and posture
Coordination of voluntary movements
Motor learning
What are the 3 main inputs into the cerebellum and what area do they feed into?
vestibulocerebellum - flocculonoddular
cerebrocerebellum - hemispheres
spinalcerebellum - vermis
to what nuclei do the vermis, paravermis and hemispheres link?
vermis - fastigial
paradermis - interposed
hemispheres - dentate
To what other areas of the brain are the cerebellar fastigial, interposed, dentate and vestibular nuclei linked to?
Fastigial - motor
interposed - motor
dentate - motor planning
vestibular - balance and eye movements
4 Steps of the spinocerebellum loop
spinocerebellar tract
vermis
fastigial/interposed nuclei
reticulo/vestibularspinal tract
6 steps of the corticocerebellum loop
cortex pons hemispheres dendate nucleus thalamus cortex
4 steps of vestibulococlear loop
vestibulocochlear
fluculonodular node
vestibular nuclei
eyes/neck muscles
What are the 3 cerebellar peduncles and are they inputs or outputs?
Superior - output
Middle - input
Inferior - input
What tracts input via the inferior and middle cerebral peduncle?
inf - Spinocerebellar
mid - corticocerbellar
What tracts output via the superior cerebral peduncle?
vestibulocerebellar
corticocerebellar
spinocerebellar
5 effects of lesions on the cerebrocerebellar pathway
dysmetria dysnergia disdisdochokinesia intentional tremor dysarthria
What term is defined as the inability to stop a movement in time?
Dysmetria
What term is defined as decomposition of complex movements?
Dsynergia
What term is defined as reduced ability to perform rapidly alternating movements?
Dysdiadochokinesia
What is an intentional tremor?
tremor arising when trying to perform a goal-directed movement
What term is defined as incoordination in the respiratory muscles, muscles of the larynx, etc. Uneven speech strength and velocity?
Dysarthria
What are the 2 effects of lesions on the vestibulo occular pathway?
Nystagmus
Inability to fixate when moving
What is the effect of lesion on the spinocerebellar pathway?
gait ataxia
What term is defined as involuntary, rhythmical, repeated oscillations of one or both eyes, in any or all directions of view?
Nystagmus
What two types of fibre input into the cerebellum and where do they come from?
Mossy fibres - spinal tract
climbing fibres from - inferior olive of medulla
Describe/draw the cerebellar circuit in terms of mossy fibres, climbing fibres granule cell parallel cell purkunje cell
mossy to granule to parallel to perkunje
climbing to perkunje
Give 2 genetic causes of cerebellar dysfunction
Frederich’s ataxia
Spinocerebellar degeneration
5 causes of acquired symmetrical ataxia
Alcohol drugs metabolic (B12) degenerative Immune
What 3 types of tissue are innervated by the ANS?
Smooth muscle
cardiac
glands
What are the 3 divisions of the ANS?
sympathetic
parasympathetic
enteric
In terms of the CNS what are anatomical divisions of the sympathetic and parasympathetic nervous systems?
Para - brainstem, S1-S4
sym - T1 - L2
The ANS works via a disynaptic pathway in all but one effector organ, which one?
adrenal glands
Explain/draw the disynaptic pathway i terms of cranial nerve ganglion effector organ myelenated unmylenated
as described
What is the main neurotransmitter in the preganglionic ANS?
Ach
What are the three ascending pathways in the spinal cord?
Spinothalamic (anterolateral)
spinocerebellar
dorsal columns (medial lemniscus)
What neurotransmitters used (post ganglion) by the sympathetic and para sympathetic nervous system?
sym Noradrenaline/NE
para - Ach
What type of receptors are employed by the sympathetic and para sympathetic nervous system pre and post ganglion?
ganglion - nicotinic Ach
post - G protein metabotropic (except adrenal medulla)
What are the two plexuses that make up the enteric nervous system and what do they regulate?
Auerbach’s - muscle contraction
Meissner’s - secretions
What are the two possible pathways of the preganglionic fibres once they enter the sympathetic trunk?
Synapse in ganglion
Pass through ganglion in splancnic nerves and synapse in prevertebral ganglia
Post ganglionic fibres are more numerous than preganglionic fibres, what is the advantage of this?
It allows for a mass response
What are the two possible pathways of the POSTganglionic fibres once they exit the sympathetic trunk?
To periphery via grey rami
To viscera via plexuses
What are the 3 ganglia in the cervical trunk, and what’s special about one of them?
Superior
Middle
Inferior - fussed to T1 ganglia to form stellate
What are the 3 possible routes for the postganglionic fibres in the cervical sympathetic trunk?
via grey rami to spinal nerves and upper limbs
piggy back down carotid artery to heart
Or up internal/external carotid to head
What condition is the disruption of sympathetic nervous supply to the head?
Horners syndrome
What are the 3 possible routes of the postganglionic fibres in the thoracic sympathetic trunk?
grey rami to spinal nerves
medial branches to heart and lungs
splancnic nerves to abdomen
What cranial nerves are associated with the parasympathetic nervous system
III
VII
IX
5 sensations of pain
Sharp stab
Deep Ache
Burning
Freezing Itch
3 classifications of pain
Nociceptive
Infalmmatory
Neuropathic
Describe A alpha and A beta fibres in terms of myelenation, diameter and sensation conveyed
Myelenated
Thick
Light touch, proprioception
Describe A delta fibres in terms of myelenation, diameter and sensation conveyed
Thinly myelenated
medium
light touch, temperature nociception
Describe C fibres in terms of myelenaations, diameter, ans sensation
Unmyelenated
thin
temperature, nociception
What are the types of nerve fibre involved in pain transmission
Alpha delta
C fibres
What type of pain is conveyed by each type of pain fibres?
Alpha delta - sharp prick
C fibres - dull ache
At what point on the pain transduction graph is the first and second response?
First large peak = A beta
First small peak = first response from A delta
last small peak = second response from C fibres
Which transient potential receptor is responsible for detecting heat?
TRPV1
Via what tract does pain ascend the spinal cord?
spinothalamic tract
How does referred pain occur with regard to synapsing of neurons?
because the first order neurons of the vicera and cutaneous synapse on the same second order neuron
What 2 regions involved in the descending regulation of pain?
PAG (midbrain) Raphe nucleus (medulla)
What effect can the Raphe nucleus have on the spinothalamic tract?
Either excite or inhibit.
So increase or decrease pain
2 examples of opioids that play a role in descending inhibition of pain
Enddorphins
Enkephalins
What receptors do opioids act upon?
Inhibitory metabotropic receptors
Give 3 sites from which opioids are released from
PAG - midbrain
Raphe - medulla
Dorsal horn
Give 3 inflammation related chemical that can activate nociceptors
ATP
H+
Serotonin
What 2 substances are related to neurogenic inflammation?
Substance P
CGRP
What term is defined as a non-noxious stimuli producing a painful response?
Allodynia
What term is defined as a noxious stimuli producing an exaggerated pain response?
Hyperalgesia
With regard to pain hypersensitisation what will peripheral and central sensitisation result in?
Peripheral - primary hyperalgesia
central - allodynia
How do bradykinin and NGF influence peripheral nerves sensitisation?
reduce threshold of heat activated channels
What are the 6 components of the basal gangia?
Putamen Globus Pallidus Internal Globus Pallidis External Caudate nucleus Substantia Nigra Subthalmaic nucleus
What makes up the striatum of the basal gangia?
Caudate nucleus
Putamen
Draw the direct pathway of basal ganglia 5
Cortex Striatum GPi Thalamus COrtex
Draw the indirect pathway 7
Cortex Striatum GPe Subthamic nucleus GPi Thalamus Cortex
Draw the hyperdirect pathway
Cortex
Subthalmic nucleus
GPi
What are the different types of dopamine receptor on medium spiney neurons in basal ganglia and what effect do they have on excitation?
D1 - ramp up excitation
D2 - dampen down excitation
On what pathways are D1 and D2 receptors founnd in the basal ganglia and what effect do they have upon excitation?
D1 - direct - ramp up
D2 indirect - damp down
Does the release of dopamine from substantia nigra inhibit or promote movement?
Promote
What neurotransmitter opposes the effects of dopamine upon the medium spiney neurons?
Ach
What condition is described as a A high amplitude flailing of the limbs on one side of the body?
Ballisimus
Where on the direct/indirect pathway is affecting in ballismus and what us the commonest cause
Subthalmic nucleus
Stroke
What makes tic disorders worse/better?
Anxeity and fatigue
Distraction and concentration
Possible causes of tic disorders
Post infectious
genetic
What condition is described as a Jerky, brief, irregular contractions that are not repetitive or
rhythmic, but appear to flow from one muscle to the next?
Chorea
Commonest causes of chorea?
Huntingtons
Neuropeltic drugs
The three areas impacted by Huntingtons
Cognitive - inability to plan
Behavioural - irritable, depression, anxiety
Motor - chorea
What disorder is Brief movement rapid onset and offset
Positive (muscular contractions) or negative (muscular inhibitions)
Myoclonus
£ common causes of myoclonus
Juvenile Myoclonic Epilepsy
Brain hypoxia
Prion disease
What condition is defined as abnormal twisting posture – often axial/ facial/ truncal, may be associated with jerky tremor
Dystonia
5 possible causes of dystonia
Stroke Brain injury Encephalitis Huntington's Parkinson's
3 types of treatment for hyperkinetic disorders
D2 blocking agents - haloperidol
Dopamine depleting agents - reserpine
Atypical antipsychotics - clozapine
3 Key side effects of dopamine blocking drugs
Oculogyric crisis - acute
Neuroleptic malignant syndrome
Drug induced Parkinsonism
3 features of neuroleptic malignant syndrome
Rigidity - raised CPK
Fever/Confusion
Autonomic instability
What condition involves lip smacking, tongue and cheek movements?
tardive dyskinesia
Treatment of tardive dyskinesia? 4
gradual withdrawal
substitute with atypical antipsychotic
dopamine depleting agent
use of benzodiazapine
Type of tremor that comes with Parkinson’s?
Resting tremor
5 Non motor symptoms of Parkinson’s?
Dementia Depression Postural hypotension Sleep disturbance Reduced sense of smell
4 non neurodegenerative causes of parkinson’s?
Drugs - haloperidol
Cerebrovascular disease
Hydrocephalus
Toxicity
Two examples of Monoamine oxidase Inhibitors and what can they be used to treat?
Selegiline
Rasagiline
For parkinson’s
Mechanism of action for lidocaine?
sodium channel blocker
How does Topical capsaicin treatment work for the treatment of acute pain?
TRPV1 agonist
Repeated use reduces nocicpetor firing
Peripheral terminals die back
How do NSAIDs reduce inflammation and therefore pain?
COX inhibited
Reduce prostaglandin synthesis
prevent’s decrease in sodium channel threshold
What is the mechanism of action for opoids and 3 sites of action?
Agonists for endogenous opoid system
Brainstem
Spinal cord
Peripheral
These statements refer to what pain related theory?
Modulation of pain at the spinal cord level
Pain evoked by nociceptors can be reduced by simultaneous activation of low threshold mechanoreceptors (Aβ fibres)
Gate control theory
2 peripheral mechanisms of chronic pain?
- Peripheral sensitization
2. Spontaneous firing of nociceptors
In chronic pain what causes the spontaneous firing of nociceptors following a nerve injury?
Accumulation of ion channels at regenerating tip of axon
What is the mechanism for central sensitisation on chronic pain?
Due to the reduced threshold for activation of 2nd order neurons
WHat are the 6 steps for reducing threshold for activation in chronic pain?
Constant firing of axons from the periphery (following injury) gives a Sustained release of glutamate
Prolonged depolarisation of the postsynaptic membrane
Massive influx of Ca2+ through NMDA receptors
Activation of kinases
Phosphorylation of NMDA/AMPA receptors
Channel protein synthesis
What is the mechanism for central hyperalgesia?
Activation of nociceptors results in amplified spinal cord activation
What is the mechanism for central allodynia?
Non-noxious Aβ fibres also synapse onto 2nd order spinothalamic neurons
Following central sensitization:
Non-noxious afferents activate sensitized 2nd order neurons
3 types of drugs that can treat chronic pain?
- Tricyclic antidepressants
- Anticonvulsants
- NMDA antagonists
AN example of tricyclic antidepressant>
Amitriptyline
Example of an anticonvulsant
carbamazepine
Example of an NMDA antagonist and mechanism of action?
ketamine
- NMDA receptor antagonist (reduces glutamate influx)
- Prevents depolarization of second order neuron
