Overview
This lecture introduces angular motion, focusing on the three primary axes of rotation in the human body and their relevance to movement in sports and anatomy.
Clarification on Terminology
- "Axes" is the plural of "axis"; "axis" is singular.
- Accurate use of these terms is important in scientific contexts.
Definition of Angular Motion
- Angular motion refers to a body or part of a body moving in a circle or part of a circle.
- In humans, all rotation occurs at the joints.
Primary Axes of Rotation
- The body has many axes of rotation, but three are considered primary and pass through the center of mass.
Longitudinal Axis
- Runs vertically from the top of the head to the feet.
- Rotation around this axis results in twisting movements (e.g., turning in netball, slalom skiing, discus throw, 180° or 360° spins).
Transverse Axis
- Runs horizontally from hip to hip (side to side through the navel).
- Rotation around this axis causes forward or backward movements (e.g., somersaults, forward rolls, seat drops in trampolining).
Frontal (Anterior-Posterior) Axis
- Runs horizontally from front to back through the body.
- Rotation around this axis results in side-to-side movements (e.g., cartwheel, star jump, diving save in football).
- The technical term "anterior-posterior axis" is also acceptable.
Joint-Specific Axes
- Each joint can have its own axis of rotation (e.g., knee, elbow, shoulder).
- Part of the body can rotate independently around these joint-specific axes.
Key Terms & Definitions
- Angular Motion — movement of a body or part in a circle or part circle.
- Axis — a straight line about which rotation occurs; plural: axes.
- Longitudinal Axis — vertical axis running head to toe, responsible for twisting rotation.
- Transverse Axis — horizontal axis from hip to hip, responsible for forward and backward rotation.
- Frontal (Anterior-Posterior) Axis — horizontal axis from front to back, responsible for side-to-side rotation.
- Center of Mass — the point through which primary axes pass in the body.
Action Items / Next Steps
- Reflect on and find sports examples for each type of rotational movement.
- Memorize the three primary axes and their corresponding movements.
- Be precise in using "axis" and "axes" in written and verbal responses.