Muscle Structure/Function

Question 1

Name the two types of contractile proteins that make up a muscle.

Answer 1

Contractile proteins - shorten muscle fiber and generate active force

1. Actin
2. Myosin

Question 2

Name the two types of non-contractile proteins that make up a muscle.

Answer 2

Non-contractile proteins - Support the structure of the muscle fiber

1. Titin: provides passive tension
2. Desmin: stabilizes alignment of adjacent sarcomeres

Question 3

True/False Fusiform muscles are longer and therefore generally able to generate more force when compared to pennate muscles.

Answer 3

False: Fuciform are longer, however, pennate have more numerous fibers per given area=greater strength/greater force production

Question 4

Agonist is the muscle which helps a body part move in a given direction, where the antagonist has the opposite action and resists the action of the agonist. The agonist for elbow extension is_______ the antagonist for elbow extension is ________.

Answer 4

Elbow extension is agonist = triceps

Antagonist for elbow extension is = biceps

Question 5

What is synergist muscles?

An example of synergistic muscles are what?

Answer 5

Synergists: muscles that cooperate during the execution of a particular movement
-FCU & FCR during wrist flexion

Question 6

A force couple is when two muscles simultaneously create force in _________ linear directions but produce a torque in the _________ direction.

Answer 6

Different

Same

Question 7

Give example of force coupling muscles working on the pelvis.

Answer 7

Erector spinae pull posterior pelvis up and iliopsoas pulls anterior pelvis downwards (opposite directions but same anterior pelvic tilt)

Question 8

A muscle contracting but not moving is an example of what?

When is this type of muscle activation useful?

Answer 8

Isometric (internal =external torques)

-Useful for early post-op rehab

Question 9

A muscle contracting and shortening in length is an example of what?

Answer 9

Concentric Isotonic movement

• Acceleration activity
• Internal>external Torque

Question 10

A muscle contracting and increasing in length is an example of what?

Answer 10

Eccentric Isotonic movement

• Deceleration activity
• Internal < external

Question 11

A machine which adjusts resistance based off the force produced by the individual to ensure they move at a preset speed is an example of what type of contraction?

Answer 11

Isokinetic

Question 12

______ type of muscle contraction places the most stress on the muscle and tendon.

Answer 12

Eccentric movement

Question 13

What is tension within a muscle?

Answer 13

Force built up

Question 14

Active tension comes from

Answer 14

contractile units (muscle generating force)

Question 15

Passive tension comes from

Answer 15

Stretching (elastic forces produced by non-contractile proteins)

Question 16

Total tension =

Answer 16

combination of active and passive tension

Question 17

Tone -

Answer 17

slight tension in muscle at all times (states of readiness)

Question 18

Our ideal resting length is the area in the ROM of a muscle is one in which the muscle has the ________ number of cross bridges.

Answer 18

Length that allows the greatest number of cross bridges

Question 19

Putting a quick stretch on a muscle just prior to contraction will create the potential for ________ force production.

Answer 19

greater

Question 20

True/False: Muscles spanning 1 joint may not have sufficient excursion to allow joint to move through entire ROM

Answer 20

False:
Muscles spanning 1 joint have sufficient excursion
Muscles spanning 2 joints may not

Question 21

____(low/high) levels of passive tension in muscles that cross multiple joints

Answer 21

High

Question 22

Passive insufficiency and active insufficiency are concepts only of _____ joint muscles.

Answer 22

2 joint muscles

Question 23

_______ insufficiency is the limitation in ROM of a muscle when the muscle is placed on stretch at both joints it crosses.

Answer 23

Passive (flex wrist, fingers straight, but when you ext wrist your fingers will flex)

Question 24

_______ insufficiency is the limitation in ability to produce force when a muscle is actively contracting at both joints it crosses.

Answer 24

Active (Wrist straight = strong fist, when flex wrist can’t create same force with fist)

Question 25

Max torque greatest at what point of flex/ext?

Least at what point of flex/ext

Answer 25

Greatest - midrange

Least - full flex or ext

Question 26

The ______ the load the ______ the speed of concentric contraction.

Answer 26

• greater the load the decreased the speed

- Smaller the load the larger the speed

Question 27

The ______ the load the ______ the speed of eccentric contraction.

Answer 27

• Larger the load the larger the speed

- Smaller the load the smaller the speed

Question 28

When attempting to stretch a one joint muscle must be aware that may need to place the two joint muscle on ______ in order to maximize the stretch at the one joint muscle.

Answer 28

2-joint muscle placed on slack to stretch the 1-joint muscle
(straight leg for gastroc stretch, bent knee for soleous stretch)