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Levers, image - Coggle Diagram
Levers
Lever systems in the body
Second class levers
Second class levers are composed of three elements, being effort, load, and fulcrum (as in the first class levers). The load is placed between the effort and the fulcrum, and is supported so. An example of these levers can be the ball of the foot, where the load that we support evolves into our toes.
Third class levers
Third class levers consist of a fulcrum, effort and load (in that same order). With the effort concentrated in the center of the lever system, an example of third class levers is seen biceps curls, where the effort is put in the muscle, whilst the weight is placed in the forearms (hands) and the movement is seen in the shoulders.
First class levers
The arrangement consists of the fulcrum being between the effort and load. The elbow is an example of a first class lever system, since it presents a relation (side and side from the fulcrum) where the triceps attach to the elbow joint, supporting the weight placed on the forearm. The effort is done by the triceps and other side supporting upper arm muscles, whilst the weight is placed below the elbow nearing the hand (as said before, forearm).
Mechanical advantages and disadvantages
First and second class lever systems provide a mechanical advantage, allowing you to move a certain weight or load from one place to an other effectively.
However, third class levers operate at a mechanical disadvantage, requiring great strength to move weight in an almost insignificant way. However, they are used in muscle strength training for this very reason. Their ineffectiveness reflects into effectiveness due to the demand that they place on your muscles, allowing you to preform simple exercises and gain significant muscle mass easily.
Planes and axes of movements
Planes of motion
Frontal plane
A plane in which you are in the same imaginary corridor, but in which you are facing the walls of the corridor, instead of facing both ends. Your movements in the plane consist of taking body parts out the sides and bringing them in again. Consider this a horizontal movement of your limbs, in which you lift them towards your side.
Transverse plane
This is imagined as a cylinder-shaped cage. As if you were trapped inside a soda can. In this case, you can only move in a rotational way.
Sagittal plane
Sagittal plane movements consists on bending and straightening your limbs, elbows, and knees. The sagittal plane is based off flexion and extension. It is imagined as a sharply narrow corridor, in which you can only move forth and bend your joints, and where you are facing the end of the corridor..
Major body axes
Frontal axis
A line that passes through the body horizontally form left to right. It is found in relation to the sagittal plane. A summersault can happen in the movement made in the frontal axis according to the sagittal plane.
Sagittal axis
The sagittal axis passes through the body from back to front, and is found in relation to the frontal plane. A cartwheel can be done in the relation between the transverse plane and the vertical axis.
Vertical axis
It is an axis passing from top to bottom of the body, and is found in relation to the transverse plane. A full twist can be done in this axis through the transverse plane.
