2) Label the lever class on the following diagrams A) Look at the dlagrams below

Question

2) Label the lever class on the following diagrams A) Look at the dlagrams below and determine whether it is first, second or third class lever. Label the Force, Axis, and Resistance. Force: Where the muscle originates on the bone. Axis: The joint the muscle crosses, where the motion occurs Resistance: The load that is being moved. Pronator Teres Brachioradialis (anterior view) Triceps brachi (posterior vicw) B) Look at the diagrams below of the Biceps brachili flexing the elbow. Describe what happens at each elbow range of motion in relation to the Bicep contraction. Discuss the force components. At what position is it the strongest? The weakest? Reference: Hinson, M.M. Kinesiology. 2 Ed. Wm. C. Brown Company Publishers, 1981

Explanation / Answer

2)

A)

Class-1 lever is the presence of fulcrum between the effort and load. The first, second and fourth diagrams show that they belong to class-1 lever.

Class-3 lever is the presence of effort between the fulcrum and load. The third diagram shows that it belongs to class-3 lever.

B)

Biceps contraction occurs maximally when the angle at the elbow is 130 degree.

At each of the angle at the elbow, the force component will be calculated as cos(x)/sin(x)

At 10degree – FC is 1.54

At 60degree-FC is 3.13

At 90degree- FC is 0.3

At 100degree- FC is 1.70

At 130degree- FC is 0.394

As the force at 60 degree is more, this position is likely to be strongest for the biceps contraction.

At 90 degree the contraction is weakest.

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