Biomechanical concepts Flashcards
What is Biomechanics
Field that combines the disciplines of biology and engineering mechanics and utilises the tools of physics, mathematics, and engineering to quantitatively describe the properties of biological materials
Kinesiology
The scientific study of human movement.
Kinesiology addresses physiological, biomechanical, and psychological dynamic principles and mechanisms of movement.
Arthrokinetics
A field that combines the disciplines of biology and engineering mechanics and utilises the tools of physics, mathematics, and engineering to quantitatively describe the properties of movement of the joints
What’s needed to make things happen
- Static structures such as bones and ligaments, dynamic structures such as muscles, proprioceptors.
- Neurological mechanisms: involved: Central control, local control, corrective measures, feedback, and feedforward loops.
- Physiological mechanisms: Vascularity, energy systems (oxygen, ATP, Fe)
- Time: Age, timelines, degeneration
- External influencing factors: Gravity, inertia, ground reaction forces
- Biomechanical principles: center of gravity, levers, torque, power, force, force coupling, form and force closure, roll, slide, and spin.
- Pathological processes: Degeneration, developmental issues, trauma, malnutrition.
What is force
A push or a pull, with an unequal force allowing an object/limb to move as a result.
6 types of force
- Tension
- Compression
- Bending
- Shearing
- Torsion
- Combined loading - think Csp
Newton’s 1st Law of Motion
Football being kicked, will remain stationary until it is kicked and will continue at the same speed until it meets another force or resistance
Newton’s 2nd Law of Acceleration
Pulling something: you need a force to make something move and the heavier the mass the greater the force you need to move it. The bigger you are the more energy needed to jump the same height
Newton’s 3rd Law of Motion – For every action there is a reaction
If you jump the force applied to the ground has a reaction in making you jump in a different direction.
Most important to osteopaths - demos holistic view.
Torque
The ability of a force to cause rotation on a lever.
E.g. the contraction of ipsilateral ES muscles on individual vertebrae leading to a rotation movement and the subsequent torque force put through the laminae of the intervertebral discs. It is the variation in fibre direction of the laminae of the discs that copes with these forces.
Supination/pronation a good example of torque being produced.
Fulcrum
A joint where a bone (lever) can move around the pivot point.
The effort force is provided by muscles and is applied to the lever system at the point where the muscle’s tendon attaches to the bone serving as the lever.
E.g. OA joint
Levers
Made up of three parts, an effort, a load, and a fulcrum. In the human body, the effort is provided by the muscle (the muscles point of application/insertion), the load is the weight of the body and any additional resistance, and the fulcrum is the joint itself.
First-class Lever
EFL
Extension/flexion of skull on atlas
Second-class Lever
FLE
Plantar flexion of foot/ankle on ball of foot
Lever Type 3
FEL
Elbow Flexion
What are the Fundamental movements through joint surfaces
Exist between curved joint surfaces: roll, slide and spin.
These movements occur as convex surfaces move on concave surfaces.
Very rare for a pure single movement to occur during articulation, there is always some form of combined movement happening.
Roll
Via one bones’ articular surface moving against another bones articular surface
Slide
To prevent an undesirable translatory movement there has to be some degree of slide, otherwise the bone will lose traction/leverage during the movement.
Also the moving bone may find itself in an undesirable position. For instance the abduction of the humerus, if there wasn’t a degree of slide at the same time as rolling then the head of the humerus will impact the inferior surface of the acromium, causing damage and loss of power through compromised leverage.
Spin
Combined with rolling, best example is the knee during extension, spin occurs during the end of extension to lock the knee on full extension.
Movement of a joint considered from 2 perspectives
Proximal on distal eg: femur on tibia during flexion produced by a squat exercise.
Distal on proximal eg tibia on femur during extension during a kick in football.
Form closure
uses the shape of one bone in relation to bones to provide stability to the surrounding joints. For mobility to occur further joint compression and stabilisation is required to withstand a vertical load.
Force Closure
The other forces such as the ligaments and muscles acting across the joint to create stability.
E.g. SIJ, talus and cuboid of the ankle and foot.
What are the 3 types of contraction
Concentric - occurs when the muscle fibers contract and move closer together, causing the muscle to shorten and the joint to move. E.g. upward movement of a bicep curl.
Eccentric -occurs when the muscle fibers are contracting but the muscle is being stretched. Often occurs when the muscle is trying to slow down or control a movement. E.g. lowering phase of a bicep curl, when the muscle is working to control the weight as it is lowered.
Isometric - occurs when the muscle fibers contract, but the muscle does not shorten or lengthen. E.g. holding a weight in the same position, such as holding a plank position in yoga
What is the difference between movers and stabiliser muscles?
Movers are large muscles such as deltoid and will be able to move a whole limb
Stabilisers are small muscles that control the range of movement and accessory movements.
Open Chain exercises
End of the chain is unattached, EG, bicep curl, dumbbell press
Closed chain exercise
Both ends of the chain are fixed, EG: Squats
Force Coupling around a pivot point
2 opposing forces rotating around a pivot point. There are multiple forces at any given moment. These can be equal or unequal, depending on the function required and balance of moving elements such as muscles and balance of stabilising elements such as ligaments.
E.g. the balance of position of the pelvis around S2 and the hip joint. Excessive contraction of Psoas muscle will lead to an anterior rotation of pelvis, excessive contraction of the hamstring group will lead to a posterior rotation of the pelvis.
Every action has a reaction, One structure compensates for another.
