Anatomical Terminology and Planes of Motion

Anatomical Terminology and Planes of Motion

• Anatomical Directions: Medial (toward the midline), Lateral (away from the midline), Superior (above), Inferior (below) are examples.

• Planes of Motion:

  • Sagittal Plane: Divides the body into left and right halves. Examples include forward lunges (primarily flexion/extension).
  • Frontal Plane: Divides the body into front and back halves. Examples include jumping jacks (primarily abduction/adduction).
  • Transverse Plane: Divides the body into top and bottom halves. Examples include torso rotations (primarily twisting/rotation).

• Axes of Rotation:

  • Sagittal Plane: Rotates around the frontal axis. Examples of movement include flexion and extension.
  • Frontal Plane: Rotates around the sagittal axis. Examples include abduction and adduction.
  • Transverse Plane: Rotates around the vertical axis. Examples include rotational movements.

Joints, Connective Tissue, and Muscle Mechanics

• Joint Classifications:

  • Synarthrodial: Immovable joints (e.g., skull sutures).
  • Amphiarthrodial: Slightly movable joints (e.g., pubic symphysis).
  • Diarthrodial (Synovial): Freely movable joints (e.g., knees and shoulders).

• Tendons: Dense connective tissue that connects muscles to bones.

Biomechanics, Levers, and Motion

• Kinematics vs. Kinetics:

  • Kinematics: The study of motion (position, velocity, acceleration).
  • Kinetics: The study of forces causing motion.

• Lever Components:

  • Fulcrum: The pivot point
  • Force (Effort): The applied force
  • Resistance: The load being moved

• Lever Classes:

  • First Class: Fulcrum between force and resistance (e.g., seesaw).
  • Second Class: Resistance between fulcrum and force (e.g., wheelbarrow).
  • Third Class: Force between fulcrum and resistance (e.g., biceps curl, most common in the body).

• Torque: Rotational force around an axis. Causes angular motion, not linear motion.

• Lever System Advantages:

  • First Class: Balance, speed, or force, depending on moment arms.
  • Second Class: Force amplification (e.g., lifting heavy loads with less effort).
  • Third Class: Speed and range of motion amplification (e.g., human limbs).

• Angular vs. Linear Motion:

  • Angular: Movement around an axis (e.g., spinning).
  • Linear: Straight-line motion.

• Object Diameter and Linear Motion: Larger diameter leads to greater linear motion from angular rotation.

• Newton's Laws of Motion:

  • 1st Law (Inertia): An object stays at rest or in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
  • 2nd Law (Acceleration): Acceleration is directly proportional to the net force and inversely proportional to the mass. (F = ma).
  • 3rd Law (Action-Reaction): For every action, there is an equal and opposite reaction.

• Momentum vs. Inertia:

  • Momentum: (Mass × Velocity) A measure of motion that requires a force to change.
  • Inertia: Resistance to changes in motion.

• Impulse: Change in momentum due to an applied force over time.

• Acceleration: Rate of change in velocity.

• Ground Reaction Force (GRF): Reaction force exerted by the ground in response to an applied force. Greater on hard surfaces than soft surfaces.

• Types of Friction:

  • Static: Resistance between stationary objects (highest resistance).
  • Kinetic: Resistance between moving objects (less than static).
  • Rolling: Resistance of a rolling object (least resistance).