Anatomical Position and Biomechanics

Kinesiology

• Kinesiology comes from the Greek words "kinesis" meaning to move, and "ology" which means science.
• It is the scientific study of movements.
• Movement, or motion, involves a change in place, position, or posture relative to some point in the environment.
• The study of human movement is a broad field encompassing anatomical, physiological, psychological or mechanical human movement evaluation.

Biomechanics

• Biomechanics combines the prefix "bio," meaning life, with the field of mechanics, the study of forces' actions.
• It is the study of human movements using physics.
• Biomechanics studies forces acting on/generated within a body, and these forces' effects on tissues, fluid, or materials used for diagnosis, treatment, or research.
• Mechanical kinesiology equals biomechanics.

Biomechanics: Kinematics versus Kinetics

• Biomechanics has two components: kinematics and kinetics.
• Kinematics is descriptive analysis.
• Kinetics is causal analysis.
• Kinematics involves qualitative analysis (naming and evaluating).
• Kinematics involves quantitative analysis (counting and measuring).
• Kinetics involves statics, the study of the body in a state of rest.
• Kinetics involves dynamics, the study of the body in a state of motion.

Kinematics

• Kinematic analysis describes movement, determining how fast an object is moving, how high it goes, or how far it travels.

Kinetics

• Kinetics studies the causal analysis of motion, examining forces that produce or change motion.
• Linear force causes linear motion and angular force causes angular motion.
• Pushing on a table might move it, depending on the push direction and strength.
• A push or pull between objects that may or may not result in motion is called a force.
• Kinetic movement analysis is more complex than kinematic analysis to comprehend and evaluate because forces cannot be seen, and only their effects can be observed.

Force

• Force has the physical quantity to accelerate or decelerate an object or change its state.
• Force has the physical quantity to change the shape of an object.
• FORCE (N) = MASS (KG) × ACCELERATION (m/s²).
• Anything that can do work is called force.
• Force is a vector quantity with magnitude and direction, and has 4 characteristics.
• The magnitude of the force is indicated by the length of the arrow.
• The direction of the force is indicated by the arrow's head.
• The point of application is indicated by the tail of the arrow, equivalent to the point of insertion.
• Line of application denotes the angle of pull, indicated by the angle of the arrow with the horizontal line.

Internal Force

• Active internal forces come from muscles.
• Passive internal forces come from ligaments, capsules, and joint reaction forces.

External Force

• Main types of External force include:
  • Gravity
  • Ground reaction force
  • Friction
  • Resistance
  • Pressure

External Forces: Gravity

• When releasing an object above the ground it falls because gravitational force attracts it to Earth.
• The force of gravity on an object is its weight.
• Weight (N) = mass (kg) x gravitational constant (g).
• W (in Newtons) = M (in kg).
• g (gravitational constant) = 9.8 m/s2 or ≈ 10.
• Gravity acts on a body at its mass center, and the force size depends directly on body mass/weight.

Gravitational Force Vectors

• Magnitude = body weight.
• Direction = downward.
• Point of application (POA) = COG (center of gravity).
• Line of application (LOA) = 90 degrees.

Ground Reaction Force (GRF)

• GRF’s magnitude is equal and its direction is opposite to the gravity force or body weight.
• Gravity and GRF constitute a forces pair, named as action and reaction forces.
• Magnitude = body weight.
• Direction = upward.
• POA (Point of application) = contact with ground.
• LOA (Line of application) = 90 degrees.

Frictional Force

• Frictional force is needed to slide one surface over another.
• Maximal frictional force depends on how firmly surfaces are pressed together.
• Frictional force depends on nature of materials in contact and their effects, due to surface roughness.
• Force vector magnitude = varying.
• Direction = opposite to movement direction.
• POA (Point of application) = contact area between surfaces.
• LOA (Line of application) = 0 degrees.

Pressure

• Pressure = total force applied per unit area of force application.
• Can be expressed by the equation:
  • P = F/A where:
    • P=Pressure
    • F=Force
    • A=Contact Area
• Enlarging contact area spreads force over a larger area, reducing pressure.
• Force vector magnitude = varying.
• Direction = perpendicular on surface.
• POA (Point of application) = contact area between surfaces.
• LOA (Line of application) = 90 degrees with surface.

Resistance

• Resistance reduces movement or stops a moving object.
• Resistance is directly related to surface area
• Resistance = aA (contact area).
• Improving body movement improves air or water resistance is reduced.
• Force Vector:
  • Magnitude-varying
  • Direction-perpendicular on the surface
  • POA (Point of application) = contact area between surfaces.
  • LOA (Line of application = 90 degrees with surface.

Anatomical Position

• Anatomical position is the standard reference point for describing anatomical parts and human movement.
• The subject in anatomical position is:
  • Standing upright with feet flat on the floor
  • Arms at the side of the body
  • Facing the observer
  • Palms are facing forward (supinated)

Fundamental Position

• The fundamental position is similar to anatomical position
• In fundamental position the arms are at the sides
• In fundamental position the palms face the body

Planes of Motion

• There are three planes used to describe segmental and body movements:

Sagittal Plane

• Sagittal plane is a vertical plane
• The sagittal plane cuts the body into right and left sides

Frontal Plane

• Frontal plane also called the Coronal plane
• Frontal plane is a vertical plane, that cuts the body into anterior (front) and posterior (back) parts

Transverse plane

• Transverse plane is a horizontal plane
• The transverse plane cuts the body into superior and inferior parts

Anatomical Axes

• An axis is a point around which a body or body segment rotates.
• There are three axes of rotation.
• Each axis is associated with a motion plane and is perpendicular to that plane.

1-Frontal Axis (Medio Lateral Axis

• The Frontal axis passes through the body from side to side
• It is perpendicular to the sagittal plane.
• Flexion and extension movements happen in the sagittal plane around the frontal axis.

2-Sagittal Axis (Antero Posterior Axis

• The Sagittal axis passes through the body from front to back
• It is perpendicular to the Frontal plane.
• Abduction and adduction occur in frontal plane around the sagittal axis.

3-Longitudinal Axis

• Longitudinal axis passes through the body from top to bottom
• It is perpendicular to the transverse plane.
• Rotation occurs in transverse plane around longitudinal axis.

Movements in the Sagittal Plane Around Frontal Axis

• Example movements include flexion and extension, common in cycling and running.
• Flexion at a joint results in a decrease of the angle between two segments that meet at the joint.
• Extension at a joint results in an increase of the angle between the two segments that meet at the joint.
• When movement goes beyond extended position, it's called hyperextension.

Movements in the Frontal Plane Around Anteroposterior Axis

• Examples of these Movements include abduction and adduction.
• Abduction happens when a body part is moved away from body midline, like shoulder, hip, and fingers.
• Adduction happens when a body part moved towards body midline, like shoulder, hip, and fingers.

Movements in the Transverse Plane Around Longitudinal Axis

• These Movements include medial, lateral rotation, and twist.
• Rotation: movement of a bone around own axis, called a pivot.
• Internal (medial) rotation: turning/rotating towards midline, like forearm turning towards body
• External (lateral) rotation: rotation away from midline, like forearm turning away from body.

Pronation

• Pronation is when the forearm and hand rotate so palms face down

Supination

• Supination is when the forearm and hand rotate so palms face up. A good way to remember this is holding a cup of soup.

Questions cover anatomical position, planes of motion, axes of rotation, and biomechanical principles. These questions test understanding of movement analysis, forces, pressure, and their application in human movement.