Motor and neuromuscular control Flashcards

Question

What are the lower motor neuron signs of motor neuron disease

Answer 1

``` Lower motor neuron signs: Weakness Muscle wasting Tongue fasciculations and wasting Nasal speech Dysphagia ```

Answer 2

decision to move elaborated associated movements (e.g Swinging arms when walking, changing facial expression to match emotions) Moderating and coordinating movement - suppressing unwanted movement Performing movements in order

Answer 3

Caudate nucleus Lentiform nucleus (putamen + external globus pallidus) Caudate + putamen = striatum Nucleus accumbens Subthalamic nuclei Substantia nigra ( midbrain) Ventral pallidum, claustrum, nucleus basalis (of meynert)

Answer 4

degeneration of substantia nigara

Answer 5

dopaminergic nucleus residing within the midbrain - project to striatum

Answer 6

1) Bradykinesia: 2) Slowness of small movements ( ie doing up buttons) 3) Hypomimic face: 4) Expressionless, mask-like (absence of movements that normally animate the face). 5) Akinesia: Difficult in initiation of movements 6) Rigidity: Muscle tone increases, causing resistance to externally impose joint movements. 7) Tremor at rest: 4-7Hz, starts in one hand (‘pill-rolling tremor’)- with time spread to other areas of the body.

Answer 7

degeneration of GABAergic neurons in the striatum, caudate and putamen. Genetic disorder : Autosomal dominant trinucleotide repeats disorder (CAG) on chromosome 4. CAG repeats generate elongated polyglutamine tail of the huntingtin protein Interferes with normal cellular function.

Answer 8

Symptoms : Chorea (Rapid jerky involuntary movements of the body, hands and face (affected first legs) Speech impairment (aphasia) Dysphagia Unsteady gait Cognitive decline and dementia manifesting at later stages of the disease.

Answer 9

``` Sudden uncontrolled flinging of extremities- contralateral symptoms ( flinging occurs on the opposite side of the body to symptoms ``` From stroke affecting subthalamalic nucleus Usually one sided

Answer 10

Inside posterior cranial fossa and separated from cerebrum above by tentorium cerebelli

Answer 11

coordinator and protector of movement

Answer 12

vestibulocerebellum spinocerebellum cerebrocerebellum

Answer 13

Regulation of gait, posture, and equilibrium | Coordination of head movements with eye movements

Answer 14

Speech coordination Adjusting muscle tone Coordination of limb movement

Answer 15

Coordination of skilled movements Cognitive function, attention, language processing Emotional control

Answer 16

Damage (tumour): syndrome similar to vestibular disease leading to gait ataxia and tendency to fall - even when sitting with eyes open

Answer 17

Damage (degeneration and trophy associated chronic alcoholism) affected mainly legs: abnormal gait and wide based stance

Answer 18

Damage affects mainly arms/skilled coordinated movements (tremor) and speech

Answer 19

Dysdiadochokinesia: Inability to perform repeated, alternating movements. Ataxia: Broad-based gait / impairment sin movement coordination + accuracy ( ie drunken gait) Nystagmus: Rapid involuntary movements of the eyes Intention tremor: Tremor, usually of the hands, that gets worsened with purposeful movements. Staccato Speech: Interrupted and non-fluent speech Hypotonia: Reduced muscle tone Dysmetria: Inappropriate force and distance for target-directed movements.

Answer 20

Extrafusal : muscle fibres that can contract Intrafusal : muscle fibres that can’t contract contain sensory organs that responds to stretch and tension in the muscle convey sensory info to CNS about the status of the muscle ( ie is muscle contracted or not) → helps with reflex activity

Answer 21

alpha motor neurons

Answer 22

Occupy grey matter of ventral horn of spinal cord Innervate extrafusal muscles fibres of skeletal muscles Activation causes muscle contraction

Answer 23

all alpha motor neurons innervating a single muscle

Answer 24

Motor unit : a single motor neuron together with all the muscle fibres that it innervates It is the smallest functional unit with which to produce force On average each motor neuron supplies about 600 muscle fibres. Stimulation of one motor unit causes contraction of all the muscle fibres in the unit

Answer 25

how many muscle fibres are supplied by one motor neuron A small innervation ratio allows for fine precise muscle control as there are small increases of muscle force generation compared to a huge muscle all contracting at once producing large amounts of force

Answer 26

Amount of tension generated Speed of contraction Fatigability

Answer 27

``` Slow ( S type 1) Fast fatigue resistant ( FR, type IIa) Fast fatigable ( FF, type IIb) ```

Answer 28

Type II muscles

Answer 29

1) Fast fatigable 2) fast fatigue resistant 3) slow

Answer 30

1) FF 2) FR 3) S

Answer 31

1) S 2) FR 3) FF

Answer 32

for function ie muscles used for postural stability have a greater proportion of slow type muscle fibres ( ie soleus muscle of the calf) which allows us to walk and stand up. Muscles used for activity ( ie gastrocnemius muscle of calf) generate much more force and are made up of more fast fibres but are more prone to fatigue

Answer 33

Recruitment | rate coding

Answer 34

( aka how many muscle fibres are used) | CNS determines which motor units are switched on and off

Answer 35

Size principle

Answer 36

Size principle: Tells the order to which muscle fibres are switch on Small units are required first generally slow twitch fibres As more force is required more units are recruited This allows fine control ( ie when writing) under which low force levels are required)

Answer 37

( aka how many times are muscle fibres contracting) A motor unit can fire at a range of frequencies As firing rate increases , force produced by the muscle increases Slow units fires at a lower frequency

Answer 38

Fibre types can change properties under many different conditions

Answer 39

Type IIB → Type IIA common under training Type I → II in cases of severe deconditioning or spinal cord injury Microgravity in space results in shift from slow to fast muscle fibre types Loss of type I and II due to ageing Preferential loss of type II fibres. This results in a large probation of type I fibres in aged muscle ( evidenced from slowe contraction time)

Answer 40

Neurotrophic factors Muscles will waste if nerve supply is cut even if arteries remain in tact ( aka this shows muscle cells need more than glucose and O2 ) Motor neurons produce growth factors ( neurotrophic factors) to: prevent neuronal death promote growth of neurons after injury Control recruitment and rate firing ( check this statement pls) ! ( aka provide Action potentials to muscles)

Answer 41

prevent neuronal death promote growth of neurons after injury Control recruitment and rate firing ( check this statement pls) ! ( aka provide Action potentials to muscles)

Answer 42

Automatic response to a stimulus that involves a nerve impulse passing inward from a receptor to a nerve centre then outward to an effect ( ie muscle / gland) without reaching the level of consciousness Involuntary coordinated pattern of muscle contraction and relaxation elicited by peripheral stimuli The magnitude and timing of which are determined respectively by the intensity and onset of the stimulus Reflexes differ from voluntary movement in that once they are released , they can’t be stopped

Answer 43

Tendon hammer strikes thigh Sensory ( stretch receptor ) in thigh senses the stimulus and delivers AP to CNS via the sensory nerve that goes through the dorsal root ganglion to the sc . Sensory neuron synapses onto a LMN which causes movement of muscle → excitatory movement of muscle and inhibitory muscle to the muscle antagonist to cause the knee jerk reaction Reflex contraction via monosynaptic reflex . This is just one example of a reflex there are many other reflexes

Answer 44

Higher centres of the CNS exert inhibitory and excitatory regulation upon the stretch reflex Inhibitory control of reflexed by CNS is dominated in normal conditions

Answer 45

Ie Jendrassik’ s maneuver : reduces the amount of inhibition that the brain / CNS exert under the reflex making the reflex stronger when clenching , making a fist or pulling against locked fingers when having the patellar tendon tapped ( in knee jerk reaction) the reflex becomes larger

Answer 46

Decerebration | Jendrassik manoeuvre

Answer 47

Activate: 1) Alpha motor neurons → muscle to cause voluntary contraction 2) Inhibitory neurons → reduce reflex reactions 3) Propriospinal neurons → interneurons that go up + down sc to activate nearby muscles 4) Gamma motor neurons → lower motor neurons supply intrafusal muscle fibres This will tell the SC the state of a muscle ie stretched / unstretched ie when the organs are stretched they cause a signal to go back to the sc and generate a reflex contraction of a muscle 5) Activating terminals of afferent fibres

Answer 48

overactive / brisk reflexes caused by UMN lesions

Answer 49

Clonus | Babinski's sign

Answer 50

Involuntary and rhythmic muscle contraction → stretching the muscle will start a reflex rhythmic contraction of muscles until someone forcibly stops the muscle from moving .

Answer 51

When sole of foot and balls of feet are stimulated with blunt instrument: the big toe curls downwards → normal Big toe circles upwards and other toes will fan out → abnormal associated with upper motor neuron lesion Note toes curl upward in infants ( this is normal) ( and hence wouldn’t be called babinski's sign as this would be normal)

Answer 52

Blow normal or absent relaxed → associated with lower motor neuron diseases ( problem with the lower motor neurons) ->

Answer 53

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