ch 11 misc

Question 1

1st class lever

Answer 1

fulcrum between effort and load

mechanical advantage/disadvantage depends on placement of effort/load in relation to fulcrum

Question 2

1st class lever:
if effort is farther from fulcrum than load -

Answer 2

a heavy load can be moved but not far or fast

Question 3

1st class lever:
if effort is farther from fulcrum than load - a heavy load can be moved but not far or fast

Answer 3

a heavy load can be moved but not far or fast

Question 4

1st class lever example

Answer 4

head resting on vertebral column
fulcrum - formed by joint between atlas and occipital bone
effort - contraction of posterior neck muscles
load - weight of anterior portion of skulls

Question 5

2nd class lever

Answer 5

load is between fulcrum and effort
always produces mechanical advantage because load is always closer to fulcrum than effort
sacrifices speed and ROM for force
produces most force
uncommon in human body

Question 6

2nd class lever example

Answer 6

standing up on your toes
fulcrum - ball of foot
effort - contraction of the muscles of the calf which raise heal off ground
load - weight of the body

Question 7

3rd class lever

Answer 7

effort is between fulcrum and load
most common in body
always produces mechanical disadvantage because effort is always closer to fulcrum than load
favors speed and ROM over force

Question 8

3rd class lever example

Answer 8

elbow joint, biceps brachii muscle, and bones of arm and forearm
fulcrum - elbow joint
effort - contraction of biceps brachii muscle
load - weight of hand and forearm

other ex: shoulder

Question 9

mechanical advantage

Answer 9

load is closer to fulcrum than effort

only relatively small effort is required to move a large load over a small distance

Question 10

mechanical disadvantage

Answer 10

load is farther from fulcrum than effort

relatively large effort is required to move a small load (but at greater speed)

Question 11

origin

Answer 11

attachment of a muscle’s tendon to the stationary bone

usually proximal

Question 12

insertion

Answer 12

attachment of the muscle’s other tendon to the movable bone
usually distal
usually pulled toward origin

Question 13

prime mover (agonist)

Answer 13

produces desired motion

contracts to cause an action

Question 14

antagonist

Answer 14

motion oppose agonist
relaxes as agonist contracts
stretches and yields to the effects of prime mover

Question 15

synergist

Answer 15

steadies movement, facilitates work of agonist (wrist in neutral position when clenching fist)
contract and stabilize intermediate joints to prevent unwanted movements at intermediate joints aiding agonist
doesnt directly do work, helps agonist do work
stabilizes joint

Question 16

fixator

Answer 16

stabilizes proximal bone
similar in action to syngerist
stabilizes origin of prime mover so that prime mover can act more efficiently
steadies proximal end of a limb while movements occur at distal end