Tissue Mechanics: Muscle

Question 1

what type of muscles are used to generate positive work?

Answer 1

mono-articular muscles

Question 2

what type of muscles are used to transfer energy between joints?

Answer 2

bi-articular muscles

Question 3

describe the fiber length as you transition from parallel muscles to pennate muscles?

Answer 3

parallel muscles (long fibers)
pennate muscles (short fibers)

Question 4

describe the change in velocity and force for parallel muscles and pennate muscles.

Answer 4

parallel muscles- low force; high velocity

pennate muscles- high force; low velocity

Question 5

what happens to the pennation angle when the muscle gets shorter?

Answer 5

pennation angle decreases

Question 6

which muscle packs more fibers (and thus more force)?

Answer 6

pennate muscles

Question 7

what does a low fiber length/muscle length ratio indicate?

Answer 7

high force muscle

low ratio: FL/ML = 0.2

Question 8

what does a high fiber length/muscle length ratio indicate?

Answer 8

high velocity muscle

high ratio: FL/ML = 0.6

Question 9

what contributes to the larger contraction force of a muscle?

Answer 9

the greater the number of cross-bridges attached to actin filaments

Question 10

a single stimulus from a motor neuron results in what response from a muscle fiber?

Answer 10

a twtich

Question 11

if the frequency of stimuli is rapid enough, what results in a response from a muscle fiber?

Answer 11

a tetanic response

Question 12

what is a concentric, isometric, and eccentric contraction?

Answer 12

concentric- shortening contraction
isometric- joint angle remains cosntant
eccentric- lengthening contraction

Question 13

which contraction develops the greatest force when maximally stimulated?

Answer 13

eccentric contraction - greatest force developed

concentric contraction - least force developed

Question 14

what is isotonic contraction?

Answer 14

uniform tension in the muscle

Question 15

what is isokinetic contraction?

Answer 15

length is changing, but at the same rate

Question 16

what is co-contraction?

Answer 16

simultaneous contraction of agonist and antagonist

Question 17

which type of muscle has a high proportion of slow-twich (type 1 fibers)? what about fast twitch (type 2a & 2b fibers)?

Answer 17

tonic or stability muscles- slow twitch (type 1) fibers

phasic or mobility muscles- fast twitch (type 2a&2b fibers)

Question 18

what are tonic or stability muscles used for?

Answer 18

used primarily to maintain posture

e.g. soleus

Question 19

what are phasic or mobility muscles used for?

Answer 19

for short powerful actions

e.g. biceps

Question 20

what is the working range for mechanical behavior of muscle?

Answer 20

70-120% of its length

Question 21

for a concentric contraction, what type (slow/fast) contractions produce more force?

Answer 21

slower contractions

Question 22

for an eccentric contraction, what type (slow/fast) contractions produce more force?

Answer 22

faster contractions

Question 23

what factors affect max. joint torque?

Answer 23

1. muscle cross-sectional area
2. position of joint
3. direction of contraction
4. speed of contraction