biomechanical principles

Question 1

biomechanics definition

Answer 1

=A field that combines the disciplines of biology and engineering mechanics and utilizes the tools of physics, mathematics, and engineering to quantitatively describe the properties of biological materials

Question 2

kinesiology

Answer 2

=The scientific study of human movement. Kinesiology addresses physiological, biomechanical, and psychological dynamic principles and mechanisms of movement.

Question 3

arthrokinetics

Answer 3

=A field that combines the disciplines of biology and engineering mechanics and utilizes the tools of physics, mathematics, and engineering to quantitatively describe the properties of movement of the joints

Question 4

what’s involved in biomechanics

Answer 4

static structures–> e.g. bones & ligs dynamic structures–> e.g. muscles & proprioceptors
neurological mechanisms–> central & local control, corrective measures. fedback & forward loops
physiological mechanisms–> vascularity, energy systems
time–> age, timelines, degeneration
external influencing factors–> gravity, inertia, ground reaction forces
biomechanical principles–> center of gravity, levers, torque, power, force, force coupling, form & force closure, roll, slide & spin
pathological processes–> degeneration, developmental issues, trauma, malnutrition

Question 5

forces

Answer 5

=push or a pull with an unequal force allowing an object/ limb to move as a result
6 types:
-tension
-compression
-bending
-shearing
-torsion
-combined loading

Question 6

newtons laws of physics

Answer 6

1st law of motion= every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force (e.g. football)
2nd law of acceleration= the acceleration of an object is dependent upon two variables - the net force acting upon the object and the mass of the object (e.g. heavier someone is= more energy needed to jump)
3rd law= for every action (force) in nature there is an equal and opposite reaction (e.g. jumping into ground- ground reaction in opposite direction)

Question 7

fulcrum

Answer 7

bone= lever & fulcrum= joint where bone moves around pivot point

effort force= from muscles–> applied to lever system at the point where tendons attach to bone serving as the lever

1st, 2nd & 3rd class levers= in OA, elbow & foot/ ankle joints

Question 8

torque

Answer 8

=a force that acts on a body through a lever arm–> the ability of a force to cause rotation on a lever
e.g.= the weight of the ball is causing a torque on the forearm with the elbow joint as the . The size of a torque depends on several things, including the distance from the pivot point to the force that is causing the torque.

Question 9

levers

Answer 9

made up of 3 parts: effort, load and fulcrum
effort= muscle
load= weight of body and resistance
fulcrum= joint
type 1–> extension/ flexion of skull on atlas (fulcrum in middle)
type 2–> plantar flexion of foot/ ankle on ball of foot (fulcrum, resistance, effort)
type 3–> elbow flexion (fulcrum, effort, resistance)

Question 10

concave, convex roll and slide principles

Answer 10

convex-concave surface movement= the convex surface rolls and slides in opposite directions. EG. GH

concave-convex surface movement= the concave surface rolls and slides in the same direction. EG; Elbow

function: Helps to maintain articular surface contact
Helps to maintain joint congruity through range of movement

Question 11

convex- concave examples

Answer 11

=the convex surface rolls and slides in opposite directions

Atlantooccipital; flexion/extension
Glenohumeral; abduction
Sternoclavicular; elevation
Wrist carpals on radial/ulnar deviation
Knee, flexion into extension (Getting up from sitting)
Knee extension into flexion (Sitting down)
Talocrural Dorsi/plantar flexion

Question 12

concave- convex examples

Answer 12

=the concave surface rolls and slides in the same direction. EG; Elbow

Elbow, ulnar humeral joint; flexion/extension

Question 13

spin examples

Answer 13

Glenohumeral flexion/extension
Screw home mechanism of knee on full extension.

Question 14

Occipitoatlanto Joint into flexion/extension

Answer 14

concave= atlas, convex= occiput rolls posteriorly & slides anteriorly
occiput is active. c1 is passive

Question 15

Glenohumeral joint into abduction

Answer 15

concave= Glenoid fossa of scapular, convex=Head of humerus, both rolls superiorly and slides inferiorly simultaneously.
The humerus spins during flexion/extension.
Scapular is fixed. Active movement is driven by humerus

Question 16

Sternoclavicular Joint into abduction

Answer 16

concave= menubrium, convex= Proximal clavicle
Both clavicle and manubrium are passive, active movement is driven by humerus and scapular

Question 17

Carpals into radial deviation

Answer 17

concave= radius, convex= proximal carpals
Movement driven actively by carpals, and passively allowed by distal radius and ulnar.

Question 18

Elbow into flexion/extension

Answer 18

concave= ulnar, convex= humerus
The humerus is passive in both flexion and extension, which is driven by active movement of the ulnar and radius

Question 19

knee flexion into extension (getting up from sitting)

Answer 19

Tibia is fixed and quadricep’s brings femur into extension.
The femur rolls anteriorly whilst sliding posteriorly.
The healthy force transmission through the patella and gradual relaxation of hamstrings to allow controlled elevation.
It is the cruciate ligaments that control the anterior/posterior slide of the tibia.

Question 20

knee extension to flexion (sitting down)

Answer 20

First for a knee to flex it must ‘unlock’ this is done by Politeus which medially rotates knee.
It is the Tibia that is fixed and the femur that is moving.
The femur is rolling posteriorly whilst sliding anteriorly.
There is an interplay between gradual contraction of hamstrings to flex knee and gradual controlled relaxation of quadriceps group to allowed controlled descent.
It is the cruciate ligaments that control the anterior/posterior slide of the tibia.

Question 21

Talocrural into plantar and dorsi flexion

Answer 21

concave= tibia, convex= talus
During dorsi flexion, the talus rolls anteriorly whilst it slides posteriorly on the calcaneum.
During plantar flexion, the talus rolls posteriorly and simultaneously slides anteriorly on calcaneum

Question 22

Screw-Home mechanism of Knee

Answer 22

Stabilising mechanism for tibiofemoral joint during extension.
Requires 10 degrees of external rotation during the last 30 degrees of extension.
It is mechanically linked to extension and flexion of knee and cannot be performed independently.
It maximizes overall contact area of adult knee.
Thus, favouring joint congruence and stability.
Remember Popliteus is the muscles that ‘unlocks’ the knee, prior to locomotion

Question 23

movement of a a joint perspectives

Answer 23

1. Proximal on distal eg: femur on tibia during flexion produced by a squat exercise
2. Distal on proximal eg tibia on femur during extension during a kick in football

Question 24

form and force closure

Answer 24

=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 is the term used to describe the other forces such as the ligaments and muscles acting across the joint to create stability.
Examples of this mechanism are the SIJ, talus and cuboid of the ankle and foot.

Question 25

types of movements

Answer 25

Concentric= the muscle tension rises to meet the resistance then remains stable as the muscle shortens
Eccentric= slow, lengthening muscle contractions
Isometric= tightening (contractions) of a specific muscle or group of 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

Question 26

force coupling around a pivot point

Answer 26

=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.
An example of force coupling around a pivot point is 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.
Another example of Force coupling is the scapula-humeral rhythm.