8: Physiology - Spinal reflexes, upper motor neurons and the control of movement Flashcards

1
Q

Which type of neuron co-ordinates pairs of agonist/antagonist muscles to relax and contract in tandem to produce movement?

A

Excitatory and inhibitory interneurons

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2
Q

Which type of interneuron acts on

a) quadriceps femoris
b) biceps femoris

in the knee jerk reflex?

A

a) Excitatory interneuron, producing knee extension

b) Inhibitory interneuron, preventing knee flexion

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3
Q

What are the three simplified steps in motor movements?

A

1. Strategy - thought re: what you’re out to do and the best way to do it

2. Tactics - sequence of muscle movements required to fulfill aim

3. Execution - activation of muscle groups to fulfill aims

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4
Q

Which parts of the CNS are responsible for

a) strategy
b) tactics
c) execution

of motor movements?

A

a) Neocortical areas (i.e areas outwith the motor cortex), basal ganglia

b) Motor cortex, cerebellum

c) Brainstem, spinal cord

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5
Q

What is the main motor pathway we need to know about?

A

Corticospinal tract

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6
Q

Where does the corticospinal tract start?

A

Pre-frontal gyrus i.e motor cortex

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7
Q

Where does the corticospinal tract decussate?

A

Pyramids of the medulla

85% of fibres swap sides

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8
Q

What is formed when 85% of motor fibres decussate at the pyramid of the medulla?

A

Lateral corticospinal tract

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9
Q

What is formed by the 15% of corticospinal tract fibres which DON’T decussate at the pyramids of the medulla?

A

Anterior corticospinal tract

still on the ipsilateral side

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10
Q

Which muscles are supplied by the

a) lateral corticospinal tract
b) anterior corticospinal tract?

A

a) Upper and lower limbs

b) Trunk (postural muscles)

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11
Q

When do anterior corticospinal tract fibres decussate?

A

At the spinal nerve levels of the muscles they supply

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12
Q

Which tracts, when allowed to excite muscles unopposed, cause

a) decorticate posturing
b) decerebrate posturing?

A

a) Rubrospinal tract

b) Reticulospinal tract

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