Lecture 3: Organization of Muscle, Motor Unit, Nerve Types

Question 1

Put in order of largest to smallest unit of organization

Muscle fiber, Muscle fascicle, Sarcomere, Myofibril, Skeletal muscle

Answer 1

Skeletal muscle > muscle fascicle > muscle fiber > myofibril > sarcomere

Question 2

Provide correct relationship of structure - contains:
A. Skeletal muscle - muscle fibers
B. Muscle fascicle - Sarcomeres
C. Muscle fiber - Thin and thick filaments
D. Myofibril - muscle fascicles
E. Sarcomere - myofibrils

Answer 2

A. Skeletal muscle - muscle fascicles
B. Muscle fascicle - muscle fibers
C. Muscle fiber - myofibrils
D. Myofibril - sarcomeres
E. Sarcomere - thin and thick filaments

Question 3

Provide correct relationship of structure - surrounded by:
A. Skeletal muscle - Endomysium
B. Muscle fascicle - Sarcoplasmic reticulum
C. Muscle fiber - Epimysium
D. Myofibril - Perimysium

Answer 3

A. Skeletal muscle - Epimysium
B. Muscle fascicle - Perimysium
C. Muscle fiber - Endomysium
D. Myofibril - Sarcoplasmic reticulum

Question 4

Site where axon and muscle fiber communicate

Answer 4

Neuromuscular junction

Question 5

Five basic components of a neuromuscular junction

Answer 5

1. motor neuron
2. motor end plate
3. synaptic cleft
4. synaptic vesicles
5. neurotransmitters

Question 6

Muscle contraction involves:
Motor nerve impulses cause release of A. _______ from B._______ which bind to receptors on the C. ________ and generate muscle contraction.

Answer 6

A. acetylcholine
B. synaptic vesicles
C. motor end plate

Question 7

Muscle relaxation involves:
A. _______ breaks down acetylcholine. B. ______ impulses stop. C. ______ moves back into sarcoplasmic reticulum preventing D. _______ and _______ from binding.

Answer 7

A. acetylcholinesterase
B. motor neuron
C. calcium
D. myosin and actin

Question 8

A single motor neuron and all the muscle fibers it controls. Functional connection between muscular & nervous systems.

Answer 8

Motor unit

Question 9

T or F: Motor Unit
A.
B. When motor unit fires, individual fibers can contract separately
C. 1 neuron may innervate several muscle fibers
D. 1 muscle fiber may be innerv. by only 1 motor neuron

Answer 9

A. True
B. False. All fibers contract together
C. True
D. False. Muscle fiber may be innvervated by several motor neurons

Question 10

How are fine control and strength control governed in muscle fibers?

Answer 10

One neuron may innervate several muscle fibers. One muscle fiber may be innervated by several motor neurons. This creates both large and small motor units for fine control and strength control. One muscle fiber may act with several motor units depending on demand.

Question 11

Twitch, Treppe, Summation, or Tetanus?

A. Occurs with low frequency stimuli (

Answer 11

A. Twitch
B. Treppe
C. Wave summation

Question 12

Twitch, Treppe, Summation, or Tetanus?
A. Reach peak tension
B. Each stimulus arrives before previous twitch is over
C. Relaxation complete before next stimulus occurs
D. Each stimulus produces identical response

Answer 12

A. Tetanus
B. Wave summation
C. Treppe
D. Twitch

Question 13

Twitch, Treppe, Summation, or Tetanus?
A. Each contraction is a little stronger than previous
B. Can be complete or incomplete
C. Single brief stimulus produces quick cycle of contraction/relaxation that lasts muscle twitches fuse

Answer 13

A. Treppe or wave summation
B. Tetanus
C. Twitch
D. Wave summation

Question 14

Tentanus: Complete or Incomplete?
A. No relaxation bet. contractions; sustained contraction
B. Occurs with max freq. stimulation = 20-40 stimuli/sec
C. Occurs with max freq. stimulation = 40-50+ stimuli/sec
D. Muscle fibers partially relax between contractions
E. Produces peak tension

Answer 14

A. Complete
B. Incomplete
C. Complete
D. Incomplete
E. Both can

Question 15

Nerve Types: Sensory, Motor or Interneuron?
A. Efferent; impulses from CNS to muscles/glands/organs
B. Transmit impulses from one neuron to another
C. Afferent; impulses from receptors to CNS

Answer 15

A. Motor
B. Interneuron
C. Sensory

Question 16

Nerve Fibers: A, B, or C fibers?
A. Unmyelinated, slower, smallest diameter, sense pain
B. Myelinated, slower
C. Myelinated, range from slow to fast; largest diameter
D. Includes alpha, beta, gamma, and delta types

Answer 16

A. C fibers
B. B fibers
C. A fibers
D. A fibers

Question 17

Types of A fibers: Alpha, Beta, Gamma, or Delta?
A. Motor efferent to muscle spindle fiber; muscle tone
B. Myelinated, thick, fastest conducting; motor efferents
C. Skin temp and pain; nociceptive
D. Myelinated, thick; touch/pressure afferents; mechanoreceptors

Answer 17

A. Gamma
B. Alpha
C. Delta
D. Beta

Question 18

T or F: Spinal Reflex Arc
A. Voluntary reaction
B. Sensory receptor –> effector organ –> interneuron
C. Sensory neuron –> sensory receptor –> effector organ
D. Sensory neuron –> interneuron –> motor neuron

Answer 18

A. False. Automatic response to stimulus without thought
B. False
C. False
D. True

Question 19

Proprioceptors: Muscle spindle, Golgi tendon, or Joint kinesthetic?
A. Located within muscle belly (intrafusal)
B. Located within tendon (extrafusal)
C. Located in and around synovial joint capsule

Answer 19

A. muscle spindle
B. Golgi tendon
C. joint kinesthetic

Question 20

Proprioceptors: Muscle spindle, Golgi tendon, or Joint kinesthetic?
A. Detects force of muscle contraction, tendon tension
B. Detects rate of muscle stretch & muscle length
C. Detects direction of movement, accel/decel, pressure, excess strain, postural changes
D. Reflexively inhibits agonist at end range of joint motion

Answer 20

A. Golgi tendon
B. Muscle spindle
C. Joint kinesthetic
D. Golgi tendon

Question 21

Proprioceptors: Muscle spindle, Golgi tendon, or Joint kinesthetic?
A. Sensory and motor innervation
B. Inhibits synergists; facilitates antagonist
C. Involuntary muscle relaxation
D. Involuntary muscle contraction

Answer 21

A. Muscle spindle
B. Golgi tendon
C. Golgi tendon. reduces tension on tendons
D. Muscle spindle

Question 22

Muscle Spindle Intrafusal fibers: Nuclear Bag or Chain?
A. Concentrated in the central part of the fiber
B. Sensitive to steady changes of length of muscle
C. Input from gamma motor neurons; produces tension
D. Sensitive to sudden rate of change in muscle length

Answer 22

A. Bag
B. Chain
C. Bag
D. Bag

Question 23

Muscle Spindle Recptrs: Primary or Secondary endings
A. Wraps arnd central noncontractile area of bag/chain
B. Associated with type 1a fiber
C. Associated with type II fiber
D. Send sensory input to CNS re: spindle length

Answer 23

A. Both
B. Primary
C. Secondary
D. Both

Question 24

Muscle Spindle Recptrs: Primary or Secondary endings
A. Respond to overall length of muscle fiber
B. Respond to rate of change in muscle fiber length
C. Smaller diameter; slower
D. Larger diameter; faster

Answer 24

A. Secondary
B. Primary
C. Secondary
D. Primary

Question 25

What are intrafusal and extrafusal fibers? Describe their relationship.

Answer 25

Intrafusal = in capsule w/in extrafusal
Extrafusal = voluntary skeletal muscle fibers.
Intrafusal fibers wrapped by type Ia and II sensory neurons that send input to CNS. Ends of intrafusal fibers attach to extrafusal fibers and receive input from gamma motor neurons to contract and to pull on spindle.

Question 26

T or F? Muscle Spindle Receptors: Golgi Tendon
A. Sensory innervation only
B. Incr. tendon tension stimulates type II sensory neurons
C. Sensitive to intense stretch and slow stretch
D. Inhibits alpha neurons to relax muscle/protect tendon

Answer 26

A. True
B. False. Type 1b
C. False. Only intense stretch
D. True

Question 27

Joint Kinesthetic Receptors: Pacinian, Ruffini, or Free?
A. Located in CT and synovial joint capsules
B. Located in most body tissues
C. Located in synovial capsules and ligaments

Answer 27

A. Pacinian corpuscles
B. Free nerve endings
C. Ruffini corpuscles

Question 28

Joint Kinesthetic Receptors: Pacinian, Ruffini, or Free?
A. Detects lateral stretch, changes in joint angles
B. Respond to rapid and sustained pressure
C. Respond to rapid pressure change, stretch, accel/decel of joint movement

Answer 28

A. Ruffini corpuscles
B. Free nerve endings and Ruffini (responds to DEEP … pressure)
C. Pacinian corpuscles

Question 29

Reflexes: Quick Stretch, Reciprocal, or Autogenic?
A. Detects stretch in muscle spindles
B. Detects stretch in Golgi tendon organs
C. Guards against potential injury to muscle
D. Guards against potential injury to tendon

Answer 29

A. Quick stretch reflex and Reciprocal Inhibition
B. Autogenic Inhibition
C. Quick stretch reflex and Autogenic Inhibition
D. Autogenic Inhibition

Question 30

Reflexes: Quick Stretch, Reciprocal, or Autogenic?
A. Inhibitory interneuron relaxes antagonist
B. Alpha motor neuron stimulates antagonist
C. 1b afferent; Inhibitory interneuron relaxes agonist; excitatory interneuron contracts antagonist
D. Respond to rapid and sustained pressure

Answer 30

A. Reciprocal Inhibition
B. Quick stretch reflex
C. Autogenic Inhibition
D. Quick stretch reflex

Question 31

Name three NMT techniques that are based on spinal arc reflexes?

Answer 31

Post-isometric relaxation
Muscle energy technique
Strain-counterstrain

Question 32

Part of a routine orthopedic and neurological examination to test the integrity of the components of the simple reflex arc. Helps determine if there is a lower or upper motor neuron lesion.

Answer 32

DTR - deep tendon reflex