Levers In The Body

Question 1

What are levers in the body?

Answer 1

• muscles & their tendinous attachments & their relationships with the joints they cross in 3 class levers
• F = force/energy
• A = axis/fulcrum
• R = resistance

Question 2

What is the class 1 lever (FAR)?

Answer 2

• connection between the skull & spine i.e., atlanto-occipital joints (see-saw)
• force/energy = posterior neck muscles
• axis/fulcrum = cervical spine
• resistance = weight of anterior skull

Question 3

What is the class 2 lever (FRA)?

Answer 3

• person doing a calf raise i.e., plantarflexion at the ankle joint (wheelbarrow)
• force/energy = calf muscles
• resistance = body weight
• axis/fulcrum = MTP joints

Question 4

What is the class 3 lever (AFR)?

Answer 4

• the most common lever in the body i.e., elbow joint when lifting a book, tweezers, nail clippers
• gives an advantage to speed over strength
• axis/fulcrum = elbow joint
• force/energy = biceps muscle
• resistance = weight resting in hand