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Basic Science
intermediate
X-Type

Moment Arms and Levers

Biomechanics

An orthopaedic registrar is reviewing biomechanical principles for the FRACS examination. She is considering how the deltoid muscle generates shoulder abduction and how the moment arm of the deltoid changes throughout the range of motion. She wants to understand the relationship between muscle force, moment arm, and the resulting joint moment. Regarding moment arms and lever systems in the musculoskeletal system:

Mark each as TRUE or FALSE

A

A moment (or torque) is calculated as Force multiplied by Moment Arm (M = F x d), where the moment a...

B

There are three classes of levers: First-class levers have the fulcrum between the effort and load (...

C

The hip joint operates as a second-class lever during single-leg stance, which provides excellent me...

D

The abductor muscle force required during single-leg stance is approximately 2-3 times body weight b...

E

Femoral offset is the horizontal distance from the center of the femoral head to a line through the ...

Answer the questions to see explanations

Click T (True) or F (False) for each option