S1_L3: Muscle Structure & Function

Question 1

Determine the corresponding descriptions of the muscle types

1. Fusiform muscle
2. Has intercalations to allow for quick continuous contraction
3. Branched muscle
4. Has many nuclei
5. It is non-striated
6. Cylindrical muscle

A. Skeletal muscle
B. Smooth muscle
C. Cardiac muscle

Answer 1

1. B
2. C
3. C
4. A
5. B
6. A

Question 2

Determine the corresponding descriptions of the characteristics of muscle tissue

1. Ability of muscle to return in its original resting length after being stretched
2. Ability of muscle to lengthen or become stretched and sustain it
3. Ability to respond to stimulation
4. Ability of muscle to generate tension and shorten in response to stimulation
5. Contributes to the passive force generated by the muscle

A. Extensibility
B. Contractility
C. Irritability / Excitability
D. Elasticity

Answer 2

1. D
2. A
3. C
4. B
5. D

Question 3

Determine the corresponding descriptions of the elastic components

1. Plays a role in stability during isometric contraction
2. Acts as a spring to store elastic energy during stretch
3. Resistance of muscle during passive stretching, maintaining alignment of muscle fibers
4. Found in tendons, aponeurosis of the muscles
5. Found in sarcolemma, muscle membranes, sarcoplasmic reticulum, perimysium, epimysium
6. From muscle membranes and surrounds the contractile component of the muscle

A. Series Elastic Component
B. Parallel Elastic Component

Answer 3

1. A
2. A
3. B
4. A
5. B
6. B

Question 4

Determine the corresponding descriptions of the skeletal muscle structures

1. Covers the fasciculus, holding together muscle fibers/cells
2. Extension of connective tissue that connects the muscle to bone
3. Covers the individual muscle fiber (myofibrils)
4. Thin, strongly adherent to the muscle, holding the fascicles together
5. Covering of the bone
6. Smallest structure of the muscle

A. Tendon
B. Periosteum
C. Epimysium
D. Perimysium
E. Endomysium
F. Myofilaments
G. Fascia

Answer 4

1. D
2. A
3. E
4. C
5. B
6. F

Question 5

Determine the corresponding descriptions of the motor unit principles

1. ↑ frequency of stimulation of motor units → ↑ percentage of time muscle fiber will develop tension
2. ↑ motor units activated → ↑ overall muscle tension
3. smaller motor neurons are activated first for energy conservation, followed by larger motor neurons

A. Recruitment Principle
B. Excitatory Rate Coding Principle
C. Size Principle

Answer 5

1. B
2. A
3. C

Question 6

Determine the corresponding descriptions of the muscle fiber types

1. Low glycolytic enzymes, force production, and fatigability
2. Oxidative-Glycolytic metabolic properties
3. Red in color
4. Slow twitch and conduction velocity
5. White in color
6. Low mitochondrial density and oxidative enzymes

A. Type I
B. Type IIa
C. Type IIb / IIx

Answer 6

1. A
2. B
3. A
4. A
5. C
6. C

Question 7

TRUE OR FALSE: Magnitude of contraction depends on number of motor units firing, frequency of firing, diameter and size of axons, and cell bodies.

Answer 7

True

Question 8

Determine the corresponding descriptions of the fiber arrangements

1. Greater power
2. Produces greater ROM
3. Fibers arranged obliquely to their tendons, at an angle
4. Longer distance of contraction (excursion)

A. Parallel
B. Pennate

Answer 8

1. B
2. A
3. B
4. A

Question 9

Determine the corresponding shape of the ff. muscles

1. Psoas
2. Thyrohyoid
3. Orbicularis oculi
4. Sternothyroid
5. Sternocleidomastoid

A. Flat
B. Fusiform
C. Strap
D. Radiate / Triangular
E. Sphincteric / Circular

Answer 9

1. B
2. C
3. E
4. C
5. C

Question 10

Determine the corresponding descriptions of the types of muscle contraction based on length

1. Work is done by the muscle
2. No muscle work generated, trying to contract but no movement of distal segment
3. Negative work
4. Work is done on the muscle, rather than by the muscle
5. Positive work
6. Tries to control the movement when there is a primary external force

A. Concentric
B. Eccentric
C. Isometric

Answer 10

1. A
2. C
3. B
4. B
5. A
6. B

Question 11

Determine the corresponding descriptions of the types of muscle contraction based on tension

1. Made possible with special machines
2. Seldom seen in human body
3. Equal Rate of Movement
4. Equal Tension

A. Isotonic
B. Isokinetic

Answer 11

1. B
2. A
3. B
4. A

Question 12

Determine the corresponding descriptions of the roles assumed by muscles

1. Muscles eliminating unwanted action produced by agonists when they develop concentric tension
2. Slow or stop a movement, usually at the end of fast and forceful contractions/movement
3. Active during acceleration of a body segment
4. Stabilize a body part against a force (internal or external)
5. Primarily active during deceleration of a body segment
6. An example is when the rhomboids keep the scapula stable when the person does water skiing

A. Agonist / Prime Mover
B. Antagonist
C. Synergist
D. Stabilizer
E. Neutralizer

Answer 12

1. E
2. B
3. A
4. C
5. B
6. D

Question 13

Determine the corresponding descriptions of the tonic and phasic muscles

1. Larger ROM, Non-Postural/Mobility Muscles
2. Do not fatigue easily, Stability/Postural Muscles
3. More type II fibers
4. Biceps, quadriceps, gastrocnemius
5. More type I fibers
6. Erector spinae, soleus, trapezius, temporalis

A. Phasic muscle
B. Tonic muscle

Answer 13

1. A
2. B
3. A
4. A
5. B
6. B

Question 14

Determine the corresponding descriptions of the shunt and spurt muscles

1. Insertion site of the muscle is close to the joint
2. Has a greater stabilizing effect
3. Insertion site of the muscle is far to the joint
4. Greater rotatory movement and ROM

A. Shunt muscle
B. Spurt muscle

Answer 14

1. B
2. A
3. A
4. B

Question 15

Determine the corresponding descriptions of the areas of the length-tension relationship

1. Optimal sarcomere length, maximum force/tension developed
2. Myosin heads cannot reach any actin
3. Gradual increase in force generated
4. Minimal cross bridge formed, less force produced
5. Generate maximum force
6. Actin and myosin are too close together, active insufficiency

A. Ascending
B. Plateau
C. Descending

Answer 15

1. B
2. C
3. A
4. C
5. B
6. A

Question 16

Determine the corresponding descriptions of the passive and active insufficiencies

1. Too much of it causes overlapping of filaments
2. Muscle will not be able to produce optimum torque
3. Decrease in torque (force) when full ROM is attempted simultaneously at all joints crossed by a multi-joint muscle
4. Elongation of muscles over two or more joints simultaneously

A. Passive Insufficiency
B. Active Insufficiency

Answer 16

1. A
2. B
3. B
4. A

Question 17

Determine the corresponding descriptions of the Adaptation to Sustained Changes in Activity Level

1. Transition of type I to type II fiber
2. Decreased percentage and atrophy of type II fibers
3. Loss of strength
4. Increased CSA of types I & II fibers

A. Increased activity
B. Decreased activity
C. Aging

Answer 17

1. B
2. C
3. C
4. A

Question 18

Determine the corresponding descriptions of the Adaptation to Prolonged Length Changes

1. Accelerates atrophy / loss of sarcomeres
2. Hypertrophy
3. Tightness → contracture
4. Induces protein synthesis and production of additional sarcomeres
5. Transition from type II to type I fibers
6. Transition from type I to type II fibers

A. Prolonged stretch
B. Prolonged shortening

Answer 18

1. B
2. A
3. B
4. A
5. A
6. B

Question 19

Determine the corresponding descriptions of the Common Muscle Injuries

1. Increased accumulation of lactic acid, dehydration, decreased O2 supply
2. Muscle pain, ischemia to the muscle
3. Felt after exercise with mod to high intensity (transient), fatigued
4. Myositis ossificans, Blood trauma
5. Muscle tenderness, accumulation of lactic acid
6. Swelling, fluid in interstitial tissue, bleeding, compression to the muscle

A. Strains
B. Contusions
C. Cramps
D. Delayed-Onset Muscle Soreness (DOMS)
E. Compartment Syndrome

Answer 19

1. C
2. E
3. D
4. B
5. D
6. E

Question 20

Determine the corresponding shape of the ff. muscles

1. Sternohyoid
2. Orbicularis oris
3. Rectus abdominis
4. Biceps brachii
5. Sartorius
6. Pectoralis major

A. Flat
B. Fusiform
C. Strap
D. Radiate / Triangular
E. Sphincteric / Circular

Answer 20

1. C
2. E
3. A
4. B
5. C
6. D

Question 21

Refers to agonists and antagonists working together for stability

Answer 21

Co-contraction (synergistic contraction)

Question 22

Determine the corresponding shape of the ff. muscles

1. Deltoid
2. Flexor pollicis longus
3. Tibialis anterior
4. Extensor digitorum longus
5. Rectus femoris
6. Soleus
7. Subscapularis

A. Uni-pennate
B. Bi-pennate
C. Multi-pennate

Answer 22

1. C
2. A
3. B
4. A
5. B
6. C
7. C

Question 23

Determine the corresponding descriptions of the ff terms

1. Function of collective force generating capability of a given muscle group
2. Reduction in force production and in shortening velocity, prolonged relaxation of motor units between recruitment
3. Too much dehydration causing muscle wasting and muscle necrosis
4. Product of muscle force and velocity of muscle shortening
5. Measurement of maximum torque by the muscle group at a joint
6. Ability of muscle to exert tension over time

A. Muscle Strength
B. Muscle Power
C. Muscle Endurance
D. Muscle Fatigue
E. Absolute Fatigue

Answer 23

1. A
2. D
3. E
4. B
5. A
6. C

Question 24

Determine the corresponding formulas of the terms relating to muscle size

1. Mδ x Mv
2. 1.056 g/cm3
3. Muscle Length (Ml) x Muscle Width (Mw) x Muscle Depth (Md)

A. Muscle Volume (Mv)
B. Muscle Density (Mδ)
C. Muscle Mass (Mm)

Answer 24

1. C
2. B
3. A

Question 25

TRUE OR FALSE: For pennate muscle fibers, the physiological (functional) cross sectional area is always larger than the anatomical cross sectional area.

Answer 25

True A larger PCSA helps pennate fibers to generate more power, compensated by packing of fibers that increases PCSA

Question 26

Refers to a function of skeletal muscle that when the body’s temperature decreases, the mechanism of shivering (involuntary contraction of muscles) produces heat and conserves it, which brings the body back to its normal temperature.

Answer 26

Thermogenesis

Question 27

The dark band in muscle fibers is aka?

Answer 27

Anisotropic band (A band)

Question 28

Basic unit of the contractile muscle structure (tension in the muscle). It expands from z line to z line.

Answer 28

Sarcomere

Question 29

The endoplasmic reticulum is where the calcium is stored in muscles. Once the AP reaches the T tubules, it initiates the release of calcium. The ER in muscles is also referred to as the ___.

Answer 29

sarcoplasmic reticulum

Question 30

Pennate muscle fibers are usually angulated at approximately ___

Answer 30

30° (Accd. to notes) Levangie: Less than 30°

Question 31

TRUE OR FALSE: In parallel fibers, Maximum Fiber Length (FLmax) = Maximum Muscle Length (MLmax).

Answer 31

True

Question 32

The larger the number of fibers packed together, the ___ the PCSA

Answer 32

greater Leads to increased power production

Question 33

TRUE OR FALSE: The physiological cross sectional area increases with pennation angle and muscle length.

Answer 33

True

Question 34

The physiological cross sectional area is the measure of CSA ___ to the fiber orientation.

Answer 34

perpendicular

Question 35

TRUE OR FALSE: In a concentric / shortening contraction, no force is produced because actin and myosin do not put effort to stay together. In an eccentric contraction, more force is produced because actin and myosin needs more effort to stay together.

Answer 35

True

Question 36

If the muscle is lengthened or shortened beyond optimal length, the amount of active tension of the muscle ___.

Answer 36

decreases There is a direct relationship between isometric tension developed by muscle and length of sarcomere

Question 37

At what position is the biceps femoris able to generate maximum force?

Answer 37

90-90 position Biceps femoris is double jointed, so it's best to act on both joints

Question 38

The phenomenon where in one joint, the muscle is elongated, in another joint, it is shortened. This special case of passive insufficiency is not stretched on other joints, only on the major joint.

Answer 38

Tenodesis

Question 39

In the Stretch Reflex Activation, a change in ___ activates the muscle spindle and its response is contraction, thus enhancing the muscle contraction.

Answer 39

length

Question 40

TRUE OR FALSE: Muscle can perform substantially more work when it is actively stretched (lengthened) prior to shortening than when it simply contracts concentrically.

Answer 40

True

Question 41

The muscle length is 10 cm, muscle width is 3 cm, and muscle depth is 2 cm. Solve for muscle density (Mδ).

Answer 41

Mδ = 1.056 g/cm^3 value of muscle density is constant

Question 42

The muscle volume is 50 cm^3. Solve for muscle mass (Mm).

Answer 42

Mm = 52.8 g

Question 43

The muscle length is 10 cm, muscle width is 3 cm, and muscle depth is 2 cm. Solve for muscle volume (Mv).

Answer 43

Mv = 60 cm^3

Question 44

Formula for contraction length (CL)

Answer 44

CL = Maximum Fiber Length (FLmax) - Minimum Fiber Length (FLmin)

Question 45

This occurs at approximately 1/3 of maximum velocity and at 1/3 of maximum concentric force.

Answer 45

Maximum power Note: In general, for power training = 1/3 of 1RM