Muscle Elasticity

Question 1

Hierarchy and structure of ECM

Answer 1

Mostly composed of collagen
Endomysium - separate muscle bellies
Perimysium - separate fascicles
Epimysium - separate myofibers

Question 2

Roles of ECM in passive elasticity

Answer 2

Titin resists sarcomere stretch

Question 3

Passive tension

Answer 3

Resting force of muscle due to neuromuscular activation

Question 4

Stiffness

Answer 4

Change in passive tension per unit stretched

Question 5

Modulus

Answer 5

Change in passive tension per unit cross sectional area per unit stretched

Question 6

Viscoelasticity

Answer 6

Amount of passive tension in the muscle depends on how long it has been held at specific length, velocity of stretch, stretch “history”

Question 7

Main macro structures contributing to passive tension

Answer 7

Proteins in ECM (basal lamina)

Question 8

Main micro structures contributing to passive tension

Answer 8

Proteins in sarcomere (titin)

Question 9

Relative role of titin in muscle elasticity

Answer 9

Resist sarcomere stretch

Question 10

Relative role of collagen in muscle elasticity

Answer 10

Makes up Endomysium, Perimysium, Epimysium
Force transmission

Question 11

Examples of stimuli that change muscle passive stiffness

Answer 11

Change muscle modulus
Change muscle size
Change muscle length