motor

Question 1

The knee jerk reflex is a simultaneous action of

Answer 1

all muscle spindle sensory neurons and activation of all motor neurons.

Question 2

stretch receptor neurons are

Answer 2

Ia afferents

each afferent in particular muscle innervates all motor neurons in that muscle

Question 3

motor reflex

Answer 3

1. negative feedback system
2. muscle is stretched–> Ia afferent endings are distorted–> initiates AP
3. APs propagate in SC–> synapse on dendrites on that muscle’s motor neuron
4. a-motor neurons fire AP and produce muscle contraction
5. relieves stress so Ia neurons are silenced

Question 4

axons DO NOT make a

Answer 4

single synapse at a single target

Question 5

Some target of Ia afferents

Answer 5

1. excitatory synapses on motor neurons of synergistic muscles
2. through interneurons, inhibit the motor neurons of antagonistic muscles.
3. motor neurons of muscle in which spindle is located

Question 6

muscle spindle arrangement

Answer 6

in parallel with extrafusal fibers

Question 7

golgi tendon organ arrangement

Answer 7

1. in series with muscle

2. when muscle contracts or is passively stretched, 1b afferents fire APs

Question 8

muscle spindle info transmitted

Answer 8

length

Question 9

golgi tendon organ info transmitted

Answer 9

force

Question 10

muscle spindle innerv

Answer 10

1. afferent and effecert innervation
2. sensory and motor innerv
3. peripheral DRG neuron processes enter spindle and wrap around intrafusal fiber middle

Question 11

peripheral DRG neuron processes enter spindle and wrap around intrafusal fiber middle

Answer 11

1. fibers get stretched, nerve endings get deformed and membrane is depol, initiating AP (afferents fire)
2. when muscle contracts, spindle becomes relaxed because its parallel orientation (afferents can’t fire)
3. intrafusal fibers are excited by gamma motor neurons and contract

Question 12

Golgi tendon organs innerv on motor neurons

Answer 12

1b afferents

1. slower than 1a afferents
2. depol to stretch or deformation
3. synapse on SC interneurons that inhibit alpha motor neurons
4. stim by active contraction of muscle

Question 13

size principle for recruiting motor neurons

Answer 13

1. grade tension on skeletal muscle, this changes the # of active motor neurons that innervate muscle
2. 1 motor neuron–> motor unit size that produces 5% increase in tension
3. smallest motor neuron are recruited first and largest ones last

Question 14

size principle for recruiting motor neurons allows the

Answer 14

force of contraction.movement to be varied based upon the specifics of a particular situation/movement

Question 15

flexor withdrawal reflex

Answer 15

1. causes you to withdraw limb when activate flexors
2. pain pathways excited flexors through polysynaptic connections with spinal interneurons
3. simultaneously excited contralateral extensors