022514 4 Reflexes Flashcards Preview

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Flashcards in 022514 4 Reflexes Deck (17):
1

This type of motor neuron has:
large soma and axon
fast conduction velocity (72-120 m/s)
innervates skeletal muscle fiber

alpha motor neuron

2

This type of motor neuron has:
small soma and axon
slower conduction velocity (18-48 m/s)
innervates muscle spindle organ

gamma motor neuron

3

Are motor units contained in skeletal and smooth muscle?

no

4

What are the three types of muscle fibers?

type I (RED)
type IIA
type IIB (WHITE)

5

What type of muscle fiber is:
slow twitch, fatigue slowly
richly vascularized supporting numerous mitochondria
small fibers
weak, persistent contraction
innervated by gamma-motor neurons

type I (RED)

6

What type of muscle fiber is:
fast twitch, fatigue rapidly
large fibers
strong, acute contraction
innervated by alpha motor neurons
not richly vascularized, not supporting numerous mitochondria
extensive sarcoplasmic reticulum

type IIB (white)

7

Abnormal reflexes are present during what type of lesion (UMN or LMN)?

UMN

8

What type of nerve fibers activate the deep tendon reflex (DTR)?

type I(a) (A-alpha)

9

What is reciprocal inhibition?

a branch of the afferents also stimulates interneuron to inhibit antagonistic efferents

10

What type of nerve fibers activate the stretch reflex?

type II (A-beta)

11

What is the stretch reflex? What causes abnormal hyperactivity of the stretch reflex?

muscle contracts when stretched by a physician, lesions in brain (UMN) delete inhibitory control mechanisms

12

What type of nerve fibers activate the clasp knife reflex?

type III (A-delta)
type IV (C)

13

What is the clasp knife reflex?

sudden decrease in resistance when physician flexes joint

14

What reflexes are normally present?

DACS

DTR
abdominal
cremasteric
stretch (+/-)

15

What reflexes are normally absent?

clasp knife
clonus
stretch (+/-)

16

These are present in UMN or LMN lesion?
flaccid (hypoactive) paralysis
fasciculations present
individual muscles affected
major atrophy

LMN

17

These are present in UMN or LMN lesion?
spastic (hyperactive) paralysis
hyperactive DTR reflex
extensor plantar reflex
groups of muscles affected
slight atrophy

UMN