Muscle Info Flashcards
Cardiac muscle tissue
heart
Smooth muscle tissue
located in the walls of the hollow visceral organs and blood vessels
Skeletal muscle tissue
located in the muscle of the skeleton. Skeletal muscles are under the control of the will; hence they are called voluntary muscles.
Skeletal muscle tissue is composed of
skeletal muscle cells
It wraps around the entire muscle
epimysium
around groups of muscle cells within the muscle
perimysium
around each individual muscle cell
endomysium
tendons
attach the muscle to the bone.
Extensibility
the muscle can be stretched like an elastic band.
Elasticity
after the muscle is stretched it can return to its normal resting length when the stretch force is removed.
Contractility
the average muscle can shorten to approximately 1/2 its resting length.
FYI
The movement a contracting muscle produces is determined by the type of joint the muscle spans and the relation of the muscle’s line of pull to the joint. Example = a muscle crossing anterior to the elbow will contract and shorten and will cause flexion of the elbow whereas a muscle crossing posterior to the elbow joint will cause extension. Keeping this in mind, a muscle located on the lateral surface of the shoulder will shorten and lift the arm up into abduction.
Isotonic Contraction
tension remains constant as the muscle shortens or lengthens. There are two types of isotonic contractions: concentric or shortening and eccentric or lengthening contractions.
Concentric or shortening Contraction
tension created overcomes the resistance and moves one attachment of the muscle toward the other.
Eccentric or lengthening Contraction
muscle slowly lengthens as it gives in to an external force which is greater than the force it is exerting. The muscle gradually returns to its normal resting length.
Isometric or Static Contraction
muscle remains contracted with no change in its length. This occurs when the muscles which are working against each other counterbalance one another. Example: attempting to lift something which is too heavy to move or pushing against a wall.
Agonist
a muscle which is directly responsible for effecting a movement, also called the prime mover.
Antagonist
a muscle whose contraction produces a movement exactly opposite from that of the agonist.
Synergist
muscles which contract at the same time as the prime mover. Generally speaking synergistic action of muscles is thought to be a team effort to produce a more efficient movement. However synergistic action may occur in normal or pathological situations.
Stabilizer
Located proximal to the moving part
