Announcements

1
Announcements

• Important Dates (for you)
• Labor Day
• Monday, Sept 7 (sodont go to class)
• Research Lecture
• Promoting Motor Competency and Physical Activity
  in Children
• Jacqueline D. Goodway, Ph.D.
• School of Physical Activity and Educational
  Services, Ohio State University
• Thursday, September 3
• 600-900 pm
• Rm 75 Holden Hall
• Tahoka Study Interested?
• Please see me before you leave

2
Basic Concepts TerminologyPlanes Axes,
Joints, Vectors Scalars, Forces Moments

• ESS 4361-001
• Lecture 2
• Readings Notes and any review textbook

3
Overview

• Review of Basic Concepts
• Planes Axes
• Joints Degrees of Freedom
• Forces Moments of Force
• Begin reading and working through Ch 1
• 1st exam will be around Sept. 19th!

4
Part 1Methods and Measurement Tools
5
Anthropometry

• Measurement of the human body
• Tools
• Scales, tape measures, calipers, video, imaging,
  cadaver studies, regression equations,
  statistical equations, population statistics,
  geometric modeling
• Measures (of whole body as well as segments)
• BSIP (segment mass, com, moment of inertia)
• Height, weight, length, circumference, breadth,
  mass
• So, in what situations would anthropometry be
  useful?

6
Kinetics

• Measure of the forces causing or occurring as a
  result of motion
• Tools
• Force plates, tensiometers, strain gauges,
  dynamometers, accelerometers
• Measures
• Impact/ground reaction forces, joint moments,
  impulse, momentum
• So, in what situations would kinetics be useful?

7
Kinematics

• Measure of motion without regard for the forces
  that cause the motion.
• Tools
• Motion Analysis
• Modeling
• Measures
• Variables of space and time
• Position, Velocity, Acceleration
• So, in what situations would kinematics be useful?

8
Part 1 Review Planes, Axes Relative Position
9
Skeleton

• Axial Skeleton
• Head
• Neck
• Trunk
• Appendicular Skeleton
• Upper extremities
• Lower extremities

10
Reference Positions

• Anatomical Position
• Standard reference point
• Palms face front
• Fundamental Position
• Similar to anatomical position
• Arms more relaxed
• Palms face inward

11
Relative Position

• Medial toward midline of the body
• Lateral away from midline of the body
• Proximal toward point of attachment
• Distal away from point of attachment
• Superior toward the top of the head
• Inferior toward the bottom of the feet

12
Relative Position

• Anterior front, ventral
• Posterior back, dorsal
• Ipsilateral on the same side
• Contralateral on opposite sides

• Relative angle
• - Included angle between two segments

13
Relative Position
14
Planes Axes

• Plane
• Flat, two-dimensional surface
• Cardinal Planes
• Planes positioned at right angles and
  intersecting the center of mass
• Divide body into perfect halves
• Axis of Rotation
• Point about which movement occurs
• Perpendicular to plane of motion

15
Cardinal Planes

• Sagittal Plane
• Left Right halves
• Medio-lateral axis (frontal)
• Frontal (Coronal)
• Front Back halves
• Antero-posterior axis (sagittal)
• Transverse (Horizontal)
• Upper Lower halves
• Longitudinal axis (transverse)
• Many other planes exist

16
Form and Function

• Structure of the human musculoskeletal system
  somewhat dictates function
• Different joints allow rotations in only certain
  planes, while restricting motion in other planes
• Think of the joint structure and how the
  muscle-tendon complex crosses the joint
• Then think of the motion that is allowed at the
  joint
• Example Hip versus Knee

17
Part 2 maybe reviewJoints Degrees of Freedom
18
Types of Diarthrodial Joints
19
Types of Diarthrodial Joints
Plane or Gliding Joint Two flat surfaces slide
over one another (Ex Carpals)
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Other Types of Joints

• Synarthrodial or Fibrous
• Bones held together by fibrous articulations
• Little or no movement
• Example
• Sutures in skull
• Amphiarthrodial or Cartilaginous
• Hyaline cartilage or fibrocartilage holds joints
  together
• Little movement (but more than synarthrodial)
• Example
• Intervertebral discs

21
Degrees of Freedom

• Degrees of Freedom (DOF)
• Number of planes in which a joint can move
• 1 DOF
• Uniaxial (hinge joint)
• Example Inter-phalangeal (flex-extend)
• 2 DOF
• Biaxial
• Example Wrist (flex-extend, ulnar-radial
  deviation)
• 3 DOF
• Triaxial
• Example Shoulder (flex-extend, abd-add, IR-ER)

22
Summary of Joints

• 7 Types of Di-arthroidal Joints
• Hinge (elbow, inter-phalangeal)
• Pivot (radio-ulnar)
• Plane, Gliding (Vertebrae)
• Ellipsoid (metacarpal-phalangeal)
• Ball and Socket (hip, shoulder)
• Condylar (knee)
• Saddle (thumb)

23
Part 3 definitely reviewScalars, Vectors,
Forces Moments

• Reading NF, Chapter 1

24
Scalars, Vectors and Tensors

• Scalars
• Described by magnitude only
• e.g., mass, energy, power, mechanical work,
  temperature
• Vectors
• Have both magnitude and direction
• e.g., velocity, force, moment, acceleration
• Represented by arrows
• Tensors
• Term referring to all such quantities in physics
  (e.g. scalars, vectors, strain)

25
Magnitude and Direction

• Magnitude
• Positive number corresponding to the numerical
  measure of that quantity
• Direction
• Noted by either a drawn or directed vector
  (arrow)
• OR
• Noted by the /- sign associated with a
  magnitude, where or is associated with a
  left, right, up, down direction.

26
Force

• Force
• Vector quantity
• A force causes or tends to cause motion
  (acceleration) or a change in shape (deformation)
  of an object
• Push
• Pull
• Rub (friction)
• Blow (impact)

Force vectors are usually drawn as arrows
indicating direction and magnitude (length of
vector).
27
Force Characteristics

• Force is a Vector Quantity
• Magnitude
• Direction
• 2 Qualities of Force Application
• Point of application
• Line of application

28
Force Classifications

• Force Classifications
• External Forces
• e.g. Ground Reaction Forces (GRF)
• Internal Forces
• e.g. Muscle and Ligament Forces
• Another classification set can be
• Non-Contact
• Contact

29
Non-Contact Forces

• Newtons Law of Gravitational Force
• The force of gravity is inversely proportional to
  the square of the distance between attracting
  objects and directly proportional to the product
  of their masses.
• G universal gravitational constant (6.67
  10-11 Nm2/kg2)
• m1 mass of one object
• m2 mass of other object
• r distance between the mass centres of the
  objects

30
Gravitational Acceleration

• Force due to Gravity
• Fg -9.81 m/s2
• We use simply g
• Attractive force of the earth on an object
• Fg (G mobject Mearth) / r2
• Weight
• Weight m a m g
• g is acceleration due to gravity (same as Fg
  above)
• Bodyweight is body mass times gravitational
  acceleration

31
Ground Reaction Forces

• Person standing on the ground
• Force exerted by the body downward (F or Wt)
• Reaction force (Ry) exerted by the ground
• Equal in magnitude, and opposite in direction
• If the body moves then additional forces act

32
Forces during Locomotion

• During locomotion
• We exert forces on the ground to create ground
  reaction forces which propel our body along (e.g.
  forward, to the side, backward)
• Ground reaction forces can be measured using a
  force plate

33
Ground Reaction Force (GRF)

• Force equal in magnitude and opposite in
  direction to the force which is applied
• Force Platform

34
Linear versus Angular Motion

• Linear Motion
• Motion in a straight line or curvilinear path
• Rectilinear
• Curvilinear
• Path of motion never crosses back on itself
• Angular Motion
• All points of a body move through the same
  angular path (not necessarily the same distance)
• Motion of a point or object about an axis of
  rotation (fixed or translating)
• Doesnt have to complete the circle

35
Linear versus Angular Motion
36
Linear versus Angular Kinetics

• Linear Kinetics
• Line of force application is through the axis of
  rotation or COM
• No rotation
• Examples?
• Angular Kinetics
• Line of force application does not pass through
  the axis of rotation
• Thus causing rotation
• Examples?

37
Torque Moment of Force

• Moment of Force (Torque)
• A force that creates rotation about an axis
• Tendency of a force to cause rotation
• Equivalent terms
• Moment
• Moment of Force
• Torque
• SI unit is the Newton-meter
• Newton meter (Nm)

38
Basic ConceptsTorque Moment of Force

• M
• Moment (M, angular)
• F
• Force (F, linear)
• d
• Perpendicular (-) distance from the axis of
  rotation to the line of force application

39
Example
40
Basic ConceptsTorque and Moment Vectors

• Moment (Torque) that load creates about the elbow
• M F d-

If the load (W) is 50kg (assume frictionless
pulley) and d- is 8cm, what is the moment created
by the load?
41
Summary

• Basic Concepts and Terminology
• Planes Axes
• Joint Degrees of Freedom
• Scalars, vectors tensors
• Forces Moments of Force

42
For next time

• More Basic Concepts Review
• Newtons Laws
• SI Units
• Rigid Body Analysis
• Free Body Diagrams
• Statics
• Continue working through Chapter 1