General Biomechanics Principles Flashcards
First class lever
Two forces applied on either side of an axis
Effort - attempts to cause movement
Resistance - force that opposes movement
Example of first class lever in body
contraction of triceps at elbow joint
Second class lever
Two forces applied on one side of an axis
Resistance between the effort force and the axis of rotation
Example of second class lever in body
Few
Toe raises
Third class lever
two forces are applied on one side of an axis
Effort force closer to axis than resistance
Example of third class lever in body
Most are
Elbow flexion
Arthrokinematics
Movement between joint surfaces
Roll
One joint surface rolling on another
Ex - movement between femoral and tibial articular surfaces of knee
Glide
Pure translatory motion of one surface gliding on another
Ex - proximal phalanx at the head of the metacarpal bone of the hand
Spin
Rotation of the movable component of the joint
Ex - Radial head and humerus
Osteokinematics
Movement between two bones
Convex - Concave rule
Convex on concave = OPP
Concave on convex = SAME
Spine - Convex rule applies at the AO joint, below C2, concave rule applies
Resting or Loose-packed Position
Where capsule and other soft tissues are in most relaxed position
Minimal joint surface contact
May perform joint play and mobs in this position
Close-packed Position
Capsule and other soft tissue are maximally tensed
Maximal contact between joint surfaces
Joint play and mobs cannot be done in this position
Normal end feels
Soft (tissue approx)
Firm (capsular or ligamentous stretch)
Hard (bone and/or cartilage meet)
