Foundations of Biomechanics I: Kinematics Flashcards Preview

DPT 726: Orthopaedic Foundations > Foundations of Biomechanics I: Kinematics > Flashcards

Flashcards in Foundations of Biomechanics I: Kinematics Deck (22)
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-study of motion
-requires knowledge of: anatomy, physiology, neurology, physics, growth and development



-an area within kinesiology
-apply mechanics to human body
-study mechanics of life
-science that examines internal and external forces acting on a body and the effects produced by these forces


Scalar Quantities

-has magnitude but no direction
-specified by a single number
-many quantities in biomechanics may become completely specified by their magnitudes
-ex: mass, volume, time, length, speed, shoe size, temp
-obey ordinary laws of addition, subtraction, multiplication, and division


Vector Quantities

-has magnitude and direction
-characterized by: a point of application, direction and line of action, quantity or magnitude
-often symbolized with arrows
-ex: velocity, acceleration, muscular force, gravity, friction
-obey ordinary laws of addition, subtraction, multiplication, division



-science --> description of motion
-no concern re: forces causing motion
-describes: type of motion, direction of motion, quantity of motion, location of motion
-clinical examples: goniometer, videotape, stop watch, PTs knee flexed to 90 degrees



-science --> effect of forces
-concern with forces that stop, cause, or change motion
-describes: magnitude of force, direction of force, type of force, location of force
-clinical examples: dynamometers, force plates, MMT, cybex


Linear Motion

-aka rectilinear motion
-object moves along linear path
-all of object's parts travel: exactly the same distance, in the same direction, at the same time
-individual points move at equal velocities
-ex: person in w/c, sled going downhill, head receiving Tx


Rotary Motion

-object moves along circular path
-all object's parts travel: through same arc, in the same direction, at same time
-movement occurs about an axis
-axis may be external or internal to body
-individual points move at different velocities
-ex: bending at elbow, raising a tilt table, marching band turning a circle


Coupled Motions

-aka general motion
-combination of linear, rotary, or curvilinear motions
-ex: lungs, riding bike, lower extremity during gait
-most human motion


Describing Joint Function: Kinematic Chains

-combo of several joints utilizing several segments
-an attempt to describe collective joint actions
-can exert way more force with closed kinematic chain than with open


Open Kinematic Chain

-distal segment moves freely in space
-movement of distal segment is less predictable
-ex: waving goodbye, follow through on jump shot, swing phase of gait


Closed Kinematic Chain

-distal segment is fixed
-movement of all joints fairly predictable
-motion at one joint influences motion at another joint(s)
-ex: pushups, stance phase of gait, opening a door



-describes gross movement of bones
-what we see
-aka anatomic or physiological ROM
-measured clinically with goniometer or inclinometer



-study of movements of joint surfaces during joint motion
-define motion not by action of long axis but by joint surface
-describing the hinge instead of the door
-aka non-physiologic or accessory motion
-what's happening internally


Arthrokinematic Terminology: Roll

-each point on moving joint surface contacts a new point on other surface
-i.e. tire rolling down road
-occurs in the direction of the swing of the bone


Arthrokinematic Terminology: Slide

-one point on moving joint surface contacts new poins on other surface
-i.e. tire sliding on ice
-direction of slide determined by the shapes of joint surfaces


Concave-Convex Rule

-slide and roll occur in the same direction
-slide occurs in same direction of long bone segment
-ex: tibia extending on a stabilized femur, proximal phalanx moving on metacarpal


Concave-Convex Rule

-slide and roll occur in opposite directions
-slide occurs in opposite direction of long bone segment
-ex: femur extending on stationary tibia, metacarpal moving on phalanx


Close-Pack Position

-joint surfaces are matched perfectly or are congruent
-maximum area of surface contact between joint surfaces
-ligaments and capsule taut
-cannot be distracted
-ex: extended tib-fib joint, extended humeroulnar joint, extended interphalangeal joint


Loose-Pack Position

-all other positions
-joint surfaces not perfectly matched
-ligaments and capsule slack
-joint surfaces can be distracted
-ex: flexed tib-fib joint, flexed humeroulnar joint, flexed IP joint


Arthrokinematics in Knee

-tibiofemoral joint
-patellofemoral joint
-close pack position and loose pack position are different for these joints


Take Home Messages

-physical therapists use kinematics daily to describe the types of motion they see clinically
-scalar and vector quantities have different characteristics and tell us different things
-human movement is comprised of linear, rotary, and coupled types of motion, and these motions can often occur simultaneously
-osteokinematics and arthrokinematics describe the motion of skeletal system in very different ways