Biomechanics Pt. 1 (8/30a) Flashcards Preview

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1

Biomechanics

Uses principles of engineering to model human movement

“The study of structure and function of biological systems by the means of the methods of mechanics” (Herbert Hatze 1974)

2

Kinematics

refers to the description of motion of a body without reference to the forces that caused the motion of the body

AKA describes motion only

3

Translational/linear motion

all points on rigid body in the same direction and same distance

EX: displacement of the body’s center of mass (approximately just anterior to sacrum in pelvis)

4

Rotational/angular motion

all points on rigid body move in circular path around pivot point

5

Axis of rotation

point that remains stationary or pivot point for angular motion

6

Linear kinematic measures

displacement (meters)

velocity (meters/second)

acceleration (meters/sec2)

7

Rotational kinematic measures

angular displacement (degrees)

velocity (degrees/second)

acceleration (degrees/sec2)

8

Do joints in the human body rotate, translate, or both?

Both

9

Center of mass (COM)

the balance point within a body, the point where gravity is assumed to act (center of gravity)

10

Center of gravity (COG)

point at which the weight of an object is concentrated

Depends on shape and mass distribution; position dependent

11

Active motion

any conscious or subconscious movement you do on your own

EX: lifting your knee, blinking, running, etc

12

Passive motion

movement that an external force physically makes you do

EX: a PT moving your knee into flexion to check ROM

13

Osteokinematics

Describes motion of a bone relative to cardinal plane of motion

angular motion

14

Frontal/coronal plane

PLANE: frontal/coronal
MOVEMENT: abduction/adduction
AXIS: anterior/posterior axis

15

Sagittal plane

PLANE: sagittal
MOVEMENT: flexion/extension
AXIS: medial/lateral axis

16

Horizontal/transverse plane

PLANE: horizontal/transverse
MOVEMENT: external/internal rotation
AXIS: longitudinal/vertical axis

17

Degrees of freedom (DOF)

number of permitted planes of angular motion at a point

18

Number of degrees of freedom

3 DOF = 1 for each angular plane

19

Exceptions to DOF in body

Not all joints allow 3 DOF

Hinge joint - 1 DOF (sagittal)

Pivot joint - 1 DOF (transverse)

Ball & socket joint - 3 DOF (frontal, sagittal, transverse)

20

Arthrokinematics

Describes motion between joint surfaces

translational motion

21

Most joints have at least a slightly curved shape, which creates a ____-____ relationship between surfaces

convex-concave

22

Joint play/Accessory joint motion

Translation motion arises from active muscles and natural laxity/looseness of a joint

23

DOF with joint play

Linear translational motion + angular motion

3 angular DOF + 3 linear DOF = 6 DOF

24

3 motions at joint surfaces

Roll
Slide/Glide
Spin

25

Roll (joint motion)

multiple points along a rotating articular surface contact multiple points on the other articular surface

26

Slide/glide (joint motion)

a single point on one articular surface contacts multiple points on another articular surface

27

Spin (joint motion)

a single point on one articular surface rotates on a single point on another articular surface

28

If you move the CONCAVE surface on the CONVEX surface...

the arthrokinematic motion between the surfaces will occur in the SAME direction as the osteokinematic motion

29

If you move the CONVEX surface on the CONCAVE surface...

the arthrokinematic motion between the surfaces will occur in the OPPOSITE direction as the osteokinematic motion

30

Closed packed joint position

best fit or most congruent position

Closed packed ligaments usually taut, motion between joint surfaces is minimal, more contact area, less space in joint