Lecture 6 - Angular Kinematics - relative vs. absolute angles

Question 1

Angular Motion:

Answer 1

Rotation about an axis

Most human movement involves rotation of a body segment around a joint

Question 2

Axis of rotation

Answer 2

is a line (real or imaginary) oriented perpendicular to the plane in which rotation occurs

Question 3

Review the Joint Motion, Plane of Motion, and Axis of Rotation table in Heidi’s Notes

Question 4

Two Types of Angles:

Answer 4

Relative
Absolute

Question 5

Relative angles:

Answer 5

Formed between the longitudinal axes of adjacent body segments

These angles occur between two segments that can each change orientation.

Question 6

Alternative Term for relative angle

Answer 6

Also known as joint angles

Question 7

example of relative angles:

Answer 7

elbow and knee joints

Ankle Angle
Knee Angle
Hip Angle
Elbow Angle

Question 8

Relative angle - Zero Degrees Posture:

Answer 8

Zero Degrees Posture: The posture representing zero degrees must be defined. Anatomical position is often used for this purpose. For instance, even though the ankle joint is around 90 degrees in the anatomical position, it can be measured as 0 degrees.

Question 9

Relative angle - Proportional to Muscle Length:

Answer 9

Joint angles are proportional to muscle length

Question 10

Absolute angle:

Answer 10

Angular orientation of a body segment with respect to a fixed line of reference (vertical or horizontal usually)

Question 11

Absolute angle - Consistent Measurement:

Answer 11

Absolute angles are measured consistently in the same direction from a single reference point.

Question 12

Absolute angle - Alternative Term:

Answer 12

Also known as a segment angle

Question 13

examples of absolute angles

Answer 13

Upper Arm Angle
Trunk Angle
Thigh Angle
Calf Angle

Question 14

Absolute angle - Application:

Answer 14

Absolute angles are particularly useful in studying activities such as lifting objects, especially in the context of issues like low back pain.

Question 15

Absolute angle - Independent Measurement:

Answer 15

A body segment’s absolute angle is measured in respect to a line, and it is not influenced by the orientation of other body parts.

Question 16

Absolute angle - Moment Arm Measurement:

Answer 16

Absolute angles are employed in biomechanics to measure the moment arm

Question 17

Tools for Measuring Angles:

Answer 17

Goniometer
Inclinometer

Question 18

Goniometer used to measure which type of angle?

Answer 18

Used for direct measurement of relative joint angles

Question 19

Goniometer:

Answer 19

Protractor with arms

• Centre placed over joint centre and the arms are aligned with the long bones
• “Elgon” is a goniometer with an electrical potentiometer at vertex

Question 20

Inclinometer:

Answer 20

A gravitationally based instrument that identifies the absolute angle of orientation of a body segment

• Like a level; measures the angle with respect to gravity