Ch. 2 - Muscle Terminology/Contraction/Role/Action

Question 1

Tendon

Answer 1

tough yet flexible bands (rope-like) of fibrous connective tissue that connect muscles to bones and other structures
- transmit the force generated by the muscles to the bone

Question 2

Origin

Answer 2

• proximal/closest attachment to the midline or center of body
• functional: the least movable/most stable part of attachment of a muscle

Question 3

Insertion

Answer 3

• the distal/farthest from the midline or center of the body
• functional: the most movable part of a muscle

Question 4

Contraction

Answer 4

tension that is developed in a muscle as a result of a stimulus
- can be used to cause/initiate, control (accelerate/decelerate), or prevent joint movement

Question 5

Isometric/static movement

Answer 5

tension is developed within the muscle but the joint angles remain constant
- used to stabilize, or maintain the joint angle

Question 6

Isotonic/dynamic movement

Answer 6

muscle developing tension to either cause or control joint movement
- cause joint angles to change

Question 7

Concentric

Answer 7

• isotonic movement
• muscle developing active tension as it shortens, causing movement against gravity, accelerate a body part to a higher speed

Question 8

Eccentric

Answer 8

• isotonic movement
• muscle lengthening under active tension, controlling the descent of the resistance, decelerate the movement of a body segment
• more likely to cause injury

Question 9

Isokinetics

Answer 9

dynamic exercise using concentric and/or eccentric muscle contractions
- speed is constant
- muscular contraction (ideally maximum contraction) occurs
- not a type of contraction

Question 10

Agonist

Answer 10

aid in the movement of a joint, through a specified plane when contracting concentrically
- prime mover: muscles that contribute significantly to causing a specific joint movement when contracting

Question 11

Antagonist

Answer 11

located on the opposite side of the agonist, and assist in the movement; or will perform the opposite action of the agonist
- contralateral muscles

Question 12

Stabilizer

Answer 12

contract to fixate or stabilize the area to enable another limb or bod segment to exert force and move
- ex: the shoulder muscles and triceps when doing a bicep curl

Question 13

Synergist

Answer 13

assist in the action of an agonist but are not necessarily prime movers, usually guide muscles

Question 14

Helping synergist

Answer 14

have an action common to each other, but also have action antagonistic to each other; help the muscle move a joint but also prevent undesired actions

Question 15

True synergist

Answer 15

contract to prevent an undesired joint action of the agonist and have no effect on the agonist action

Question 16

Neutralizer

Answer 16

counteract or neutralize the action of other muscles to prevent undesirable movements

Question 17

Force couples

Answer 17

occur when two or more forces are pulling in different directions to make one movement on an object, causing the object to rotate about its axis
- ex: serratus anterior, middle and lower trap. causing the scapula to rotate

Question 18

Tying roles of muscles together: kicking a ball

Answer 18

• hip flexors and knee extensors are agonists
• hamstrings are antagonists
• precision depends on many other muscles

Question 19

How can muscle action be determined?

Answer 19

• line of pull
• description of the direction of force exerted by a muscle, depending on the orientation of its fibers, skeletal attachments, the disposition of its tendons, and the axis of movement of any joints affected

Question 20

How else can muscle action be determined?

Answer 20

• palpation (limited by location of muscle, type of movement, legality)
• electromyography
• electrical muscle stimulation

Question 21

All or none principle

Answer 21

All muscle fibers will be recruited/activated or none at all

Question 22

Motor unit

Answer 22

Single motor neuron and all the muscle fibers it innervates

Question 23

Latent period

Answer 23

Brief period of milliseconds following a stimulus

Question 24

Contraction phase

Answer 24

Muscle fiber begins shortening, lasts about 40 ms

Question 25

Relaxation phase

Answer 25

Follows contraction phase, lasts about 50 ms

Question 26

Summation

Answer 26

Stimuli is provided before relaxation phase, produces sustained and greater tension
- the longer the fibers, the longer a summation can be

Question 27

Tetanus

Answer 27

All muscle fibers have reached max tension, stimulus is being provided at a frequency high enough that no relaxation can occur btwn contraction

Question 28

Supramaximal stimulus

Answer 28

All muscle fibers are recruited