reflexes and segmental reflexes

Question 1

reflex

Answer 1

involuntary stereotypes response to a sensory input
-involves receptor structure

Question 1

stretch reflex

Answer 1

the contraction of a muscle in response to its passive stretching.
monosynaptic reflex, no interneurons
-known as deep tendon reflexes (DTR’s)
-stimulation occurs and sends information through 1a afferents which go to the dorsal root ganglia outside the spinal cord into the spinal cord through dorsal gray horn. then goes to the ventral gray horn to alpha motor neurons and sends out alpha motor neurons to command the reflex

Question 2

stretch reflex (DTR) order of steps

Answer 2

stimulation, 1a afferent, dorsal root ganglia, dorsal gray horn to ventral gray horn, alpha motor neurons, outward to reflex

Question 3

1a afferents are ……

Answer 3

fast afferent neurons

Question 4

H-reflex (hoffman)

Answer 4

electrical stimulation of posterior tibial nerve
-response measured by surface EMG electrodes
-stimulation through electrodes to 1a afferent neurons into the spinal cord with a synapse on alpha motor neurons and sending out through peripheral nerves and measuring activity on the nerve

Question 5

tonic vibratory reflex (TVR)

Answer 5

high frequency vibration is applied to the muscle belly or tendon casuing minute stretching of spindles
-stimulate muscle to contract
-can help contractions when trying to rehabilitate

Question 6

with the reflex, what does the high frequency vibration correlate to

Answer 6

100-300 Hz

Question 7

tendon organ reflex

Answer 7

activated by trying to stretch a muscle during an isometric contraction
-muscle tensions increases quickly
-from golgi tendon organ through 1b afferent carrying to dorsal root ganglia into the dorsal rote, synapsing on interneurons, through alpha motor neuron onto the muscle

Question 8

flexor reflex

Answer 8

what we do when we interact with a painful stimulus
-causing withdrawl of a limb away from a painful stimulus

Question 9

flexor reflex order of steps

Answer 9

pain sensation into spinal cord (using dermatome pathway), comes in on dorsal side through the spinothalamic pathway up a couple segments to find the muscle to get the limb away from stimulus and synapses on interneurons through the alpha motor neuron to remove from pain
-will continue up to the synergist muscles if needed

Question 10

two additional reflexes that occur with the flexor reflex

Answer 10

reciprocal inhibition and crossed extension reflex

Question 11

reciprocal inhibition

Answer 11

activated the move and reflex the antagonist so it does not slow you down
-spinal cord mediates it all
-occurs at the same time as the flexor reflex
-allows for smooth movements

Question 12

crossed extension reflex

Answer 12

when activating one and inhibiting the other, it is activating the other leg to take the weight so you do not fall
-preparing the opposite limb of side of the body to stabilize yourself

Question 13

babinski sign

Answer 13

testing on the foot
-using the edge of something, stroke the foot up the lateral side and across the toes from small to big toe
-mediated by the flexor reflex afferents

Question 14

normal response of the babinski sign

Answer 14

extension of the ankle and pointing of the foot and small toe

Question 15

abnormal response of the babinski sign

Answer 15

flaring of toes
-normal for 6 months and younger

Question 16

sign of bing

Answer 16

sticking the top of the foot with a pin, normal reaction is to extend the ankle to move away from the painful stimulus
-abnormal is due to UMN lesions is to flex the toe and foot upward