Levers Types And Examples of Levers of the Body

 Examples of all three Orders of levers are found in the human body, but those of the 3rd Order are most numerous.

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Mechanical Advantage.
Lever at Home and at Work 

Ist Order. ➤

The feature of this Order is stability, and a state of equilibrium can be achieved either with or without mechanical advantage. One example of this type of lever is demonstrated during nodding movements of the head; the skull represents the lever, the

Atlanto-occipital joints the fulcrum, the weight is situated anteriorly in the face, and the effort is supplied by the contraction of the posterior Neck Muscles, applied at their attachment to the 

occipital bone,

 Another example is tilting movements of the pelvis on the femoral heads.

2nd Order➤

This is the lever of power as there must always be a mechanical advantage. An example in the lower limb is demonstrated when the heels are raised to stand on the toes. The tarsal and metatarsal sal bones are stabilised by muscular action to form the lever, the ful scrum is at the metatarsophalangeal joint, and the weight of the body is transmitted through the ankle joint to the talus The effort is applied at the insertion of the tendo-calcancum by the contraction Muscles

 In the arm, the action of Brachioradialis Muscle elbow joint can be taken as another example of a type of lever which relatively uncommon in the body.

3rd Order➤

 In the human body there are more examples of the 3rd Order of levers than of any other type.

mechanical disadvantage  in this type of levers first and second order livers, is the lever of velocity,

 he loss of mechanical advantage being outweighed by the advantage gained by speed and range of movement. Both in the days of primi- tive man and in modern times, speed and range of movement have often proved to be a greater asset than power.

When the lever is the forearm, the fulcrum is the elbow joint, and when the effort is supplied by the contraction of the Brachialis Muscle applied at its insertion, and the weight is some object held in the hand,

 it can be seen that a small amount of muscular contraction will be translated into a much more extensive and rapid movement at the hand.

The action of the Hamstring Muscles in flexing the knee is other simple example.

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Mechanical Advantage.
Lever at Home and at Work