Levers

Question 1

A joint forms the ____ and the muscle crossing a joint applies ____ to move a weight/resistance.

Answer 1

A joint forms the axis (fulcrum) , and the muscles crossing a joint applies force to move a weight/resistance.

Question 2

What is the:

1. Lever
2. Lever arm
3. Fulcrum
4. Torque

Answer 2

1. Lever - The bone
2. Lever arm - The distance the lever creates
3. Fulcrum - The pivot point of the lever (usually the joint)
4. Torque - The degree to which a force rotates an object on a joint

Question 3

What is a

1. First class lever
2. Second class lever
3. Third class lever

Answer 3

1. First class lever:
   - The axis is between the resistance (weight) and the force.
   - e.g. Resistance (weight) is the head, the axis is the joint and the force comes from posterior muscles attaching to the skull.
2. Second class lever:
   - The resistance (weight) is between the axis and the force.
   - e.g. Axis is formed by metatarsaphalageal joint, the force is applied to the heel by the gastrocenimus/soleus muscle.
3. Third class lever: (most common)
   - The force is applied between the resistance (weight) and the axis.
   e. g. join is the axis, resistance is forearm, writs and hand and the force is the bicep muscle when contracted.

Question 4

If 2 muscles of the same strength cross a joint which would produce more torque?

Answer 4

The one that is father a way from the joint would be perceived as stronger

Question 5

The muscle that inserts ___ to the joint will produce a ____ range of movement

Answer 5

The muscle that inserts closer to the joint will produce a greater range of movement

Question 6

The ___ the ROM, the ___ the muscle

Answer 6

The greater the range of movement, the weaker the muscle

Question 7

Name examples of a class 1, 2 and 3 lever

Answer 7

1. Seated dumbell overhead tricep extension
2. Standing calf raise
3. Seated bicep curls, leg curl and leg extension