Muscle Function pt2

Question 1

active tension

Answer 1

tension developed by the contractile elements of the muscle

Question 2

what is active tension initiated by

Answer 2

cross bridge formation and movement of the actin and myosin

Question 3

passive tension

Answer 3

tension developed in the passive non-contractile components of the muscle

Question 4

where is passive tension developed

Answer 4

the parallel elastic components of the muscle

Question 5

what is w/in the connective tissue that surrounds the muscle

Answer 5

titin (protein)

nerves and vessels

Question 6

what is the length-tension relationship

Answer 6

there is a direct relationship b/w tension development in a muscle and length of a muscle

there is an optimal length at which a muscle is capable of developing maximal tension

Question 7

optimal length

Answer 7

where a muscle is capable of developing maximal tension

optimal length is close to what is called “resting length”

1.2 times resting length

Question 8

when do muscles develop maximal tension

Answer 8

at optimal length

b/w the actin and myosin are positioned for the maximum number of cross bridges

Question 9

what happens when a muscle is shortened or lengthened beyond optimal length

Answer 9

force producing capabilities are decreased

too long –> minimal cross bridging, no tension generated

too short –> unable to shorten anymore, no cross bridging, no tension

Question 10

what happens at optimal length

Answer 10

maximal number of cross bridges

maximal shortening

maximal tension (optimal tension)

Question 11

what position will the body tend to put the muscles at when maximal tension is required

Answer 11

optimal length

optimal length = optimal tension

Question 12

why is positioning of our patients while they perform their exercises important?

Answer 12

the position we place our patients in can alter the tension-length relationship

we allow the patient’s muscle to be @ an advantage to produce the optimal amount of tension

Question 13

single joint muscles

Answer 13

muscles that cross only one joint

ex: brachialis

Question 14

multi joint muscles

Answer 14

muscles that cross two or more joints

more efficient than 1 joint muscles

Question 15

why are multi-joint muscles more efficient than single joint muscles

Answer 15

they can maintain an optimal length tension relationship throughout the range of motion

Question 16

where do muscle insufficiencies primarily occur

Answer 16

multi-joint muscles

Question 17

2 types of muscle insufficiencies

Answer 17

active insufficiency and passive insufficiency

Question 18

2 types of active insufficiency

Answer 18

too long

too short

Question 19

active insufficiency

Answer 19

TENSION

the diminished ability of a muscle to produce or maintain active tension

occurs when a muscle is too short or too long

Question 20

too long active insufficiency

Answer 20

the muscle is elongated to a point at which there is no overlap b/w the actin and myosin

no cross bridges

no cross bridges = no active tension

Question 21

example of too long active insufficiency

Answer 21

hip flexion and knee extension

Question 22

too short active insufficiency

Answer 22

the muscle has shortened to a point at which no further sliding of the filaments can take place

cross bridges are maximally overlapped

no sliding –> no active tension

Question 23

when does too short active insufficiency occur

Answer 23

when the full AROM is attempted simultaneously at all joints by the muscle

Question 24

too short active insufficiency example

Answer 24

hip extension and knee flexion

Question 25

what positions do you avoid with patients

Answer 25

every muscle has 2 positions of active insufficiency these positions are those to avoid

Question 26

passive insufficiency

Answer 26

**ROM** occurs when a muscle is of insufficient length to permit completion of the full ROM available @ the joints crossed by the muscle the muscle isn't long enough to provide full ROM @ all joints the muscle crosses

Question 27

what happens when the muscle develops passive tension

Answer 27

may be enough to pull the bony lever in the direction of passive pull tendinosis

Question 28

what is tendinosis

Answer 28

muscle creates enough passive tension to pull the bony lever

Question 29

example of passive insufficiency

Answer 29

hamstrings in the supine position, when the hip is being pushed into flexion, there is a point the knee will begin to flex d/t the amount of passive tension

Question 30

active v. passive insufficiency

Answer 30

while both are related to the length of the muscle... passive involves elastic or passive elements active involves the contractile or active elements

Question 31

a position of passive insufficiency will...

Answer 31

always be one of the positions of active insufficiencies when the muscle is too long

Question 32

types of muscle action

Answer 32

isometric contraction isotonic contraction

Question 33

isometric contraction

Answer 33

constant length (length never changes) the distal and proximal attachments are fixed (distance =0) shortening occurs at the myofibril level (visible length remains unchanged) no mechanical work is performed

Question 34

isotonic contraction

Answer 34

constant tension tension never changed

Question 35

2 types of isotonic contraction

Answer 35

concentric and eccentric

Question 36

concentric contraction

Answer 36

shortening contraction origin and insertion move closer together positive work is being done by the muscle

Question 37

eccentric contraction

Answer 37

lengthening contraction origin and insertion move apart muscle lengthens while it maintains tension negative work is done tends to be about control

Question 38

when does eccentric contraction occur

Answer 38

when the forced that the muscle generates is insufficient to offset an opposing force on a lever or the resisting force of gravity

Question 39

force production according to contraction type

Answer 39

eccentric contraction will produce the most tension concentric contraction produces the least tension

Question 40

reverse muscle action

Answer 40

occurs when the muscles distal attachment is fixed and the proximal is free proximal bony component is pulled towards the distal bony component origin moves towards the insertion can occur in a concentric or eccentric contraction

Question 41

agonist muscle

Answer 41

muscle that is responsible for producing a desired motion at a joint

Question 42

types of agonist muscles

Answer 42

prime movers secondary mover

Question 43

prime movers

Answer 43

agonists the muscle that plays the greatest role in completing the movement

Question 44

secondary mover

Answer 44

agonist does not consistently work in completing the movement but may be recruited to assist

Question 45

antagonist

Answer 45

the muscle that has an action directly opposed to that of the agonist

Question 46

synergist

Answer 46

refers to those muscles that help the agonist to perform a desired action may assist the agonist directly or indirectly

Question 47

how does a synergist directly assist the agonist

Answer 47

helping to perform the desired action

Question 48

how does a synergist indirectly assist the agonist

Answer 48

stabilizing a part or by preventing an undesired action

Question 49

types of synergists

Answer 49

conjoint synergy neutralizing synergy stabilizing synergy or co-contraction

Question 50

conjoint synergy

Answer 50

when 2 or more muscles act together to produce a movement that neither muscle could do alone

Question 51

example of conjoint synergy

Answer 51

radial deviation flexor carpi radialis and extensor carpi radialis longus there is no specific muscle or muscle group that performs radial deviation

Question 52

neutralizing synergy

Answer 52

when a 2 joint muscle contracts, there may be an undesired motion at one of the joints so another muscle will contract to "neutralize" that undesired motion

Question 53

example of neutralizing synergy

Answer 53

finger flexion during finer flexion, wrist extensors neutralize the finger flexion they prevent the wrist from flexion to preserve the tension-length relationship if the wrist were to flex, there would be active insufficiency and we wouldn't be able to produce as much tension

Question 54

stabilizing synergy or co-contraction

Answer 54

the contraction of agonists and antagonists of a proximal joint to allow 1) highly coordinated movements OR 2) forceful contraction of a more distal joint

Question 55

example of stabilizing synergy or co-contraction

Answer 55

finger flexion elbow flexors and extensors stabilize the elbow while we flex our fingers to produce more force proximal stability to produce force distally

Question 56

stabalizing or co-contraction involves

Answer 56

an agonist and antagonist

Question 57

neutralizing synergy involves

Answer 57

an agonist and some other muscle group

Question 58

spurt muscles

Answer 58

a muscle whose proximal attachment (origin) is far from the joint axis insertion is close tot he axis results in large ROM

Question 59

what happens when the insertion is close to the axis

Answer 59

has a large rotary or mobility component

Question 60

shunt muscles

Answer 60

a muscle whose proximal attachment (origin) is close to the joint axis insertion is far from the joint axis ex: brachioradialis during elbow flexion

Question 61

what happens when insertion is far from the joint axis

Answer 61

has a large translatory or stability component

Question 62

shunt v. spurt

Answer 62

shunt --> stability spurt --> mobility