Term
| What signs would you expect to find in upper motor neurone lesions? |
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Definition
Hyper reflexia- reduced inhibition.
Increased spastic tone- pyrimidal weakness. Legs extensor spasticity and arms flexor spasticity.
Spastic Paraparesis - Above presentation in both legs
Spastic Quadraparesis – Above presentations in all 4 limbs |
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Term
| What signs would you expect to find in lower motor neurone lesions? |
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Definition
| Reduced tone and weakness and hyporeflexia - Dennervation or loss of final pathway. |
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Term
| What is the cauda equina? |
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Definition
| Lower motor neurones at the bottom of the spinal chord which finishes at ~L1. |
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Term
| Which are the motor and sensory tracts in the spinal chord? |
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Definition
Motor- Anterior and lateral corticospinal tract
Sensory- Dorsal column and spinothalamic tract. |
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Term
| Describe the spinothalamic tract |
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Definition
Lateral potition in spinal chord.
Carries pain and temperature sensation.
Fibres decussate at level of entry into spinal chord. |
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Term
| Describe the Dorsal column |
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Definition
Dorsal position in spinal chord.
Carries fine touch, proprioception and vibration sensation.
Fibres decussate in medulla. |
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Term
| Describe the pyramidal tracts |
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Definition
Anterior and lateral position in spinal chord.
Carries ~90% of preganglionic motor neurones to somatic origins.
Lateral fibres decussate in the medulla, anterior fibres decussate at level of exit. |
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Term
| Describe the extrapyrimidal tracts |
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Definition
| Responsible for the modulation of motor signals, the power and co-ordination of them. |
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Term
| What supplies blood to the spinal chord? |
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Definition
| Anterior spinal artery at anterior medial fissure and 2 posterior spinal arteries. |
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Term
| What might occlusion of the anterior spinal artery result in and what clinical signs would you therefore expect to see? |
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Definition
| Ischaemia of the corticospinal and spinothalamic tracts resulting in only sensation and proprioception remaining. |
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Term
| What are the red flag signs of cauda equina? |
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Definition
| Urinary retention, faecal incontinence and saddle anaethesia. |
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Term
| What are the subdivisions of the autonomic nervous system? |
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Definition
Sympathetic- Fight or flight
Parasympathetic- Rest and Digest
Enteric- governs function of GI system |
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Term
| What is the origin of the sympathetic nervous system? |
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Definition
Toraco-lumbar outflow-All preganglionic fibers of sympathetic division arise from cell bodies of preganglionic neurons located in spinal cord segments T1-L2.
Neurons leave anterior rami via rami communicantes and enter sympathetic chain. |
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Term
| What is different about the sympathetic preganglionic neourones innervating the adrenal medulla? |
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Definition
| They leave at the same level and do not synapse |
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Term
| Describe preganglionic sympathetic neurones |
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Definition
Short
Myelinated
Release ACh (w/Nicotinic Receptors to receive on postganglionic neurone)
Synapse with several postganglionic neurones |
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Term
| Describe postganglionic sympathetic neurones |
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Definition
Unmyelinated
Release noradrenaline (all other than sweat glands which release ACh). |
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Term
| What is the origin of the parasympathetic nervous system? |
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Definition
| Cranio-sacral outflow- cranial nerves 3,7,9 &10. Sacral S2-S4 segments. |
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Term
| Describe the pathway of the parasympathetic nervous system. |
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Definition
| Long preganglionic neurones (via cranial/sacral) ->synapse close to effector organs -> few postganglionic neurone synapses. |
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Term
| Describe parasypathetic preganglionic neurones |
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Definition
Long
Myelinated
Release ACh (w/Nicotinic Receptors to receive on postganglionic neurone)
Synapse with fewer postganglionic neurones (compared to sympathetic) |
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Term
| Describe parasypathetic postganglionic neurones |
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Definition
Unmyelinated
Release ACh (muscarinic receptor receive) |
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Term
| What is Postural hypotension and how is it caused by an ANS disorder? |
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Definition
Caused by slow/insufficient reaction of the ANS when a person stands up
Can also be a side effect of α1 adrenergic blockers |
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Term
| What is Horners Syndrome and how is it caused by an ANS disorder? |
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Definition
| Unilateral ptosis, miosis and anhidrosis as a result of damage to the sympathetic supply of the eye i.e at sympathetic chain or carotid plexus |
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Term
| What is Freys syndrome and how is it caused by an ANS disorder? |
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Definition
| Diversion of the parasympathetic fibres supplying the parotid gland to the skin above it resulting in sweating below the ear when they salivate. |
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Term
| What are the acetylcholine receptors? |
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Definition
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Term
| What are the roles of nicotinic receptors and where do they present? |
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Definition
Ionotropic and excitatory.
Present on :Postganglionic Sympathetic & Parasympathetic Neurones, Neuromuscular Junctions (Effectors of PNS) and the Adrenal Medulla. |
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Term
| What drugs target nicotinic receptors? |
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Definition
Nicotine - Nicotinic receptor agonist; Increases HR & BP
Addictive effects due to its action on CNS receptors. |
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Term
| What is the role of muscarinic receptors and where do they present? |
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Definition
Metabotropic.
Present on parasympathetic effectors in different tissue specific distribution depending on subtype (M1-M5). |
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Term
| What drugs target muscarinic receptors? |
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Definition
Muscarine - Muscarinic receptor agonist, found in poisonous mushrooms, causes parasympathetic overstimulation & may be fatal.
Pilocarpine - Specific M3 receptor agonist, used in eyedrops to treat glaucoma.
Atropine - Muscarinic receptor antagonist, found in deadly nightshade, used in resus - blocks bradycardic action of parasymp. system on heart and used to dilate pupil (mydriasis). |
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Term
| What are the 2 noradrenaline receptors and what is their role? |
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Definition
| α & β Adrenergic Receptors, both metaboropic. |
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Term
| Where do α1 Receptors present? |
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Definition
Vascular smooth muscle, pupillary dilators, heart
Agonists e.g. Phenylephrine used in hypotension, Antagonists in hypertension. |
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Term
| Where do β1 and β2 receptors present? |
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Definition
β1 Receptors present on heart.
β2 on respiratory/uterine/vascular smooth muscle, skeletal muscle & liver.
•Agonists increase HR, bronchodilate e.g. Salbutamol
•Antagonists reduce HR/contractility e.g. Beta Blockers |
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Term
| What drugs target noradrenaline at receptors? |
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Definition
Cocaine - NA reuptake inhibitor
Amphetamines - Increase NA release |
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Term
| What signs would you expect with a cerebral lesion? |
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Definition
| Unilateral (Usually), Associated Sensory Symptoms, Dysphasia, Personality Changes, Seizures |
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Term
| What signs would you expect with a brain stem lesion? |
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Definition
| Diplopia, Dysphagia, Dysarthria, Cranial Nerve Symptoms, Sensory Symptoms |
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Term
| What signs would you expect with a Spinal Chord lesion? |
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Definition
| Bilateral (Usually), Bladder/Bowel/Sexual Dysfunction, Sensory Symptoms, hyperreflexia |
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Term
| What signs would you expect with an anterior horn cell pathology? |
|
Definition
| Mixed UMN,LMN Signs - Weakness, Wasting, Arreflexia, Fasciculations, fibrillations |
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Term
| What signs would you expect with a peripheral nerve cell pathology? |
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Definition
| Specific distribution (according to nerve)/Symmetrical distal weakness (according to myotome), Sensory Symptoms |
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Term
| What signs would you expect with a neuro-muscular junction pathology? |
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Definition
| Fatiguable weakness, specific distribution, possible autonomic features |
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Term
| What signs would you expect with a muscular pathology? |
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Definition
| Wasting, Occasional Pain, Systemic Features, Proximal Distribution (Often) |
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Term
| What is Motor Neurone Disease? |
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Definition
| Disease causing wasting of the anterior horn cells resulting in both upper and lower motor neurone signs. |
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Term
| The anterior and posterior horns contain what sort of neurones? |
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Definition
Anterior- Motor
Posterior- Sensory |
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Term
| What is peak presentation incidence of motor neurone disease? |
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Definition
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Term
| How is motor neurone disease diagnosed? |
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Definition
Clinical diagnosis
May have moderately elevated creatanine kinase. |
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Term
| How is motor neurone disease treated? |
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Definition
Riluzole- Glutamate antagonist, may increase life span.
Physio
Nocturnal ventilator support
Nutritional support
Palliative care |
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Term
| What is myaesthenia gravis? |
|
Definition
| Acquired Autoimmune Disease, against nicotinic acetylcholine receptor at neuro-muscular junction, results in Muscle Weakness & Fatiguability. |
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Term
| What are the symptoms of myaesthenia gravis? |
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Definition
Fatiguable Weakness - Muscles become ↑weaker during periods of activity, with improvement after rest.
Affects central muscles more than peripheral.
Sudden or gradual onset. |
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Term
| What investigations would you carry out when suspecting myaesthenia gravis? |
|
Definition
Serology - ACh & MuSK antibodies
Neurophysiology - Muscle fatigue measured after repitive stimulation by electric current.
Edrophonium Test - ACh breakdown at NMJ blocked by edrophonium, relieving weakness temporarily. |
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Term
| How is myaesthenia gravis treated? |
|
Definition
Acetylcholine Esterase Inhibitors-Neostigmine, Pyridostigmine
Surgery- Thymectomy
Antibody Treatment- Plasmapheresis, IV immunoglobulins.
Immunosuppressive Drugs- Cyclosporine, azothioprine and presnisone. |
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Term
| What is muscular dystrophy? |
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Definition
• Group of inherited disorders of muscle structure e.g. Duchenne ~/ Becker’s ~/ Congenital MD
oCharacterised by progressive wasting & weakness |
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Term
| How would you investigate suspected muscular dystrophy? |
|
Definition
Elevated Serum Creatinine Kinase - CK released on muscle breakdown
DNA testing
Muscle Biopsy |
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Term
| What drug induces rhabdomyolosis, myalgia and myositis as a side effect? |
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Definition
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|
Term
| What is polymyositis and how is it treated? |
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Definition
Tcytotoxic cells invade & destroy muscle fibres causing an adult onset of proximal weakness and myalgia.
Immunosuppressive treatment- Methotrexate and azathioprine. |
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Term
| What is Dermatomyositis and how is it treated? |
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Definition
Antibodies attack capillaries & small arterioles in muscle, skin etc. causing proximal weakness and fever with a rash.
Immunosuppressive treatment- Methotrexate and azathioprine. |
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Term
| What is inclusion body myositis? |
|
Definition
Elderly onset of progressive muscle weakness.
No response to immuno-suppressants and cause unknown. |
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|
Term
| What is the final pathway? |
|
Definition
Simple reflex circuit:
Sensory Receptor -> Afferent path to CNS -> Synapse within CNS -> Efferent path from CNS -> Effector |
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Term
| What neurones enter/leave the dorsal and ventral routes? |
|
Definition
Sensory neurones enter spinal chord by dorsal routes.
Motor neurones leave spinal chord by ventral routes. |
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Term
| What is the role of the inhibitory interneurone? |
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Definition
| Send inhibitory signals to antagonist muscles of movement. |
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Term
| What are muscle spindles? |
|
Definition
| Stretch receptors embedded within intrafusal muscle fibres. |
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|
Term
| What are golgi tendon organs? |
|
Definition
| Stretch receptors embedded in tendons |
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Term
| What is the role of α-Motor Neurones? |
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Definition
| Innervate normal (extrafusal) muscle fibre |
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Term
| What is the role of γ-Motor Neurones? |
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Definition
| Innervate intrafusal muscle fibres, determine stretch in fibre and therefore calibrate muscle fibres to fire at the correct amount of stretch. |
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Term
| What is the myotactic reflex? |
|
Definition
Basic spinal reflex from muscle spindles.
Stimulus stretches muscle spindle-> afferent impulse ->CNS :
Efferent motor neurone->stretch of same
Inhibitory interneurone -> inhibits antagonist
Efferent pathway -> muscle. |
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Term
| What is recurrent inhibition? |
|
Definition
| Inhibits continuous firing of motor neurones via renshaw cells. |
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Term
| What is the role of Renshaw cells? |
|
Definition
Stimulated by the efferent motor impulse.
Inhibit same motor neurone and synergistic neurones. |
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Term
| What is the inverse myotatic reflex? |
|
Definition
| Provides a negative feedback via the golgi tendon organs resulting in reduced stretch in muscle. |
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|
Term
| What is the flexor withdrawal reflex? |
|
Definition
Protective withdrawal from noxious stimulus via nociceptors.
Leads to flexion of ipsilateral limb and extension of contralateral limb. |
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|
Term
| What 5 regions of the cerebral cortex are involved in movement? |
|
Definition
Primary motor cortex
Primary somatosensory cortex
Premotor cortex
Supplementary motor area
Posterior parietal cortex |
|
|
Term
| Where is the primary motor cortex and what is its role? |
|
Definition
Located on precentral gyrus.
Sends motor impulses directly to effectors .
Made up of motor homonculus |
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Term
| Where is the primary somatosensory cortex and what is its role? |
|
Definition
Located on postcentral gyrus
Receives sensory infomration from receptors, made up of sensory homonculus. |
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Term
| Where are the pre motor cortex and the supplementary motor area and what are their roles? |
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Definition
Anterior to primary motor cortex.
Responsible for programming complex movements e.g postural adjustment.
Interacts with primary motor cortex and sends fibres directly. |
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Term
| Where is the posterior parietal cortex and what is its role? |
|
Definition
Posterior to primary sensory cortex.
Integrates visual and sensory information. |
|
|
Term
What is apraxia?
Damage in what areas would cause this? |
|
Definition
Inability to perform complex motor actions.
Supplementary motor area, primary motor cortex and posterior parietal cortex. |
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|
Term
|
Definition
| Denial/ignorance of a medical condition. |
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