Kinematics and articular movement Flashcards
(30 cards)
How many variables are needed for a complete description of the body?
A complete description of the total body (feet + legs + thighs + trunk + head + upper arms + forearms and hands = 14 segments) in 3D requires 15 data x 14 segments = 210 data variables.
If we make the following simplifications in symmetrical level walking:
- Sagittal plane movement
- Ignore the arm movement
- Consider head, arms, and trunk (HAT) to be a single segment
- Symmetry (we need to collect data from one lower limb only)
How many variables are needed for a complete description of the movement?
The data variables in this case (leg + foot + thigh + HAT= 4 segments, one plane) can be reduced to 9 (position, linear velocity and linear acceleration in x and y, and angle, angular velocity and angular acceleration in plane xy) x 4 segments = 36 variables.
What is angular motion?
The motion that occurs when all parts of a body move through the same angle but do not undergo the same linear displacement.
Definiton of absolute or segment angle
The segment angle or absolute angle of a segment is the angle relative to the right horizontal.
Definiton of relative or joint angle
This is the angle between longitudinal axes of two segments. The joint angle does not change with body orientation. A relative angle (e.g., the elbow angle) can describe the amount of flexion or extension at the joint.
Relative angles, however, do not describe the position of the segments in space.
Electrical potentiometer that can be attached to measure a joint angle
Goniometer
Force transducers designed to measure the reaction forces associated with a given acceleration
Accelerometer
Definition of raw data
Unprocessed data. Raw data contain additive noise (electronic noise, spatial precision of film digitizing system, or human error in film digitizing).
Degree to which a joint is allowed to move before restricted by the surrounding tissue such as
tendons, muscle, and ligaments.
Joint mobility
Refers to the degree of congruence between the articular surfaces. It depends on the shape, size, and arrangement of the articular surfaces, the surrounding ligaments, and the tone of the surrounding muscles.
Joint stability
Degrees of freedom of pivot and hinge joints
One (examples: knee and elbow joints).
Degrees of freedom of condyloid and saddle joints
Two (examples: carpometacarpal and metacarpophalangeal joints).
Degrees of freedom of ball and socket joints
Three (examples: hip and glenohumeral joints).
Definition of degree of freedom (d.o.f)
Number of independent motions that are allowed to the body.
Moment arm
Perpendicular distance between the axis and the line of action of the force.
Ratio between the resistance force and the action force
Mechanical advantage
The motion in which the relative angle
between the foot and the leg decreases
Dorsiflexion
The movement in which the lateral border of the
foot lifts so that the sole of the foot faces away from the midline of the body
Eversion
The action in which the relative angle between
two adjacent segments gets larger
Extension
The motion in which the relative angle between the foot and the leg increases
Plantarflexion
Movement in which the front or ventral surface rotates to face downward, as seen in the forearm and foot
Pronation
The plane that bisects the body into right and left sides
Sagittal Plane
Movement in which the back or dorsal surface rotates upward, as seen in the forearm and foot
Supination
The plane that bisects the body into top and bottom halves
Transverse (Horizontal) Plane
