KINESIOLOGY OF THE
MUSCULOSKELETAL
SYSTEM
Dr. Michael P. Gillespie
KINESIOLOGY
Kinesis – to move
Logy – to study
VITRUVIAN MAN – LEONARDO DA
VINCI
Dr. Michael P. Gillespie
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MUSCULORUM CORPORIS HUMANI BERNHARD SIEGFREID ALBINUS
Dr. Michael P. Gillespie
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KINEMATICS
Kinematics describes the motion of a body
without regard to the forces or torques that
produce the motion.
 In biomechanics the term body can describe the
entire body or any of its parts. It can describe
specific regions, segments, or bones.
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Dr. Michael P. Gillespie
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TWO TYPES OF MOTION
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Dr. Michael P. Gillespie
Translation – a linear motion in which all parts
of a rigid body move parallel to and in the same
direction as every other part.
Rectilinear – translation in a straight line.
 Curvilinear – translation in a curved line.
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
Rotation – a motion in which an assumed rigid
body moves in a circular path around some pivot
point.
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TRANSLATION & ROTATION
Movement of the body as a whole is described as
translation of the body’s center of mass (located
just anterior to the sacrum).
 The movement of the body is powered by muscles
that rotate the limbs.
 The phrases “rotation of a joint” and “rotation of
a bone” are used interchangeably.
 The pivot point for angular motion is called the
axis of rotation.
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Dr. Michael P. Gillespie
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TYPES OF MOVEMENT
Active movement – movement caused by
stimulating a muscle.
 Passive movement – movement caused by
sources other than active muscle contraction.
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Dr. Michael P. Gillespie
Push from another person
 Pull of gravity
 Tension in stretched connective tissues
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VARIABLES AND UNITS OF
MEASUREMENT RELATED TO
KINEMATICS

Variables related to kinematics
Position
 Velocity
 Acceleration
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Dr. Michael P. Gillespie
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Units of measurement
Translation – meters or feet
 Rotation – degrees or radians
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INTERNATIONAL SYSTEM OF UNITS
This system is widely accepted in many journals
related to kinesiology and rehabilitation.
 It is abbreviated SI, for Systeme International
d’Unites, the French name.
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Dr. Michael P. Gillespie
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COMMON CONVERSIONS BETWEEN
UNITS
English Units
1 meter (m) = 3.28 feet (ft)
1 ft = 0.305 m
1 m = 39.37 inches (in)
1 in = 0.0254 m
1 centimeter (cm) = 0.39 in
1 in = 2.54 cm
1 m = 1.09 yards (yd)
1 yd = 0.91 m
1 kilometer (km) = 0.62 miles
(mi)
1 mi = 1.61 km
1 degree = 0.0174 radians (rad)
1 rad = 57.3 degrees
Dr. Michael P. Gillespie
SI Units
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OSTEOKINEMATICS

Sagittal plane – runs parallel to the sagittal suture of
the skull and divides the body into right and left
sections.
 Frontal plane – runs parallel to the coronal suture of
the skull and divides the body into anterior and
posterior sections.
 Horizontal plane (transverse) – runs parallel to the
horizon and divides the body into upper and lower
sections.
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Dr. Michael P. Gillespie
Osteokinematics describes the motion of bones
relative to the three cardinal (principal) planes of
the body.
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CARDINAL PLANES OF THE BODY
Dr. Michael P. Gillespie
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A SAMPLE OF COMMON
OSTEOKINEMATIC TERMS
Common Terms
Sagittal Plane
Flexion and extension
Dorsiflexion and plantar flexion
Forward and backward bending
Frontal Plane
Abduction and adduction
Lateral flexion
Ulnar and radial deviation
Eversion and inversion
Horizontal Plane
Internal (medial) and external
(lateral) rotation
Axial rotation
Dr. Michael P. Gillespie
Plane
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AXIS OF ROTATION
Bones rotate around a joint in a plane that is
perpendicular to an axis of rotation.
 The axis is typically located through the convex
member of a joint.
 The shoulder allows movement in all three
planes and therefore has three axes of rotation.
 The axes of rotation are depicted as stationary;
however, in reality, each axis shifts slightly
throughout the range of motion.
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Dr. Michael P. Gillespie
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DEGREES OF FREEDOM
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Dr. Michael P. Gillespie
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Degrees of freedom are the number of independent
directions of movements allowed at a particular joint.
A joint can have up to three degrees of angular freedom which
correspond to the three cardinal planes.
For purposes of kinesiology, degrees of freedom indicates the
number of permitted planes of angular motion at a joint.
Strictly speaking, from an engineering perspective, degrees of
freedom would also include translational (linear) as well as
angular movement.
Natural laxity within the joint structure allows for some
translation. This is referred to as accessory movement or joint
“play”.
The amount of passive translation can be used clinically to
asses the integrity of the joint. Excessive translation can
indicate ligament injury or laxity.
Abnormal translation can affect active movements and lead to
increased intra-articular stress and microtrauma.
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OSTEOKINEMATICS

Movement of a joint can be considered from two
perspectives:

State the bone that is considered the primary
rotating segment.
Dr. Michael P. Gillespie
1. The proximal segment can rotate against the
relatively fixed distal segment.
 2. The distal segment can rotate against the
relatively fixed proximal segment.
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Tibial-on-femoral movement
 Femoral-on-tibial movement
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UPPER EXTREMITY
OSTEOKINEMATICS
Most routine movements of the upper extremity
involve distal-on-proximal segment kinematics.
 We bring objects held by the hand either closer to
or further away from the body (i.e. eating and
throwing a baseball).
 The proximal segment is stabilized by muscles,
gravity or inertia.
 The distal segment segment rotates with fairly
free movement.
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Dr. Michael P. Gillespie
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LOWER EXTREMITY
OSTEOKINEMATICS
The lower extremities perform both proximal-ondistal and distal-on-proximal segment
kinematics.
 These kinematics are apparent in walking during
the stance phase and the swing phase.
 Kicking and squatting are also good examples of
distal-on-proximal and proximal-on-distal
kinematics respectively.
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Dr. Michael P. Gillespie
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DISTAL-ON-PROXIMAL & PROXIMALON-DISTAL KINEMATICS
Dr. Michael P. Gillespie
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OPEN AND CLOSED KINEMATIC
CHAINS
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Dr. Michael P. Gillespie
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The terms “open” and “closed” are typically used to
indicate whether the distal end of an extremity is
fixed to the earth or some other immoveable object.
An open kinematic chain describes a situation in
which the distal segment of the kinematic chain is not
fixed to the earth or other immoveable object.
A closed kinematic chain describes a situation in
which the distal segment of the kinematic chain is
fixed to the earth or another immoveable object.
From an engineering perspective, the terms apply to
the kinematic interdependence of a series of
connected rigid links.
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ARTHROKINEMATICS
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
Roll
 Slide
 Spin
Dr. Michael P. Gillespie
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Arthrokinematics describes the motion that occurs
between the articular surfaces of joints.
The shapes of articular surfaces range from flat to
curved. Most joint surfaces are at least slightly
curved. One side is convex and the other is concave.
This convex-concave relationship improves joint
congruency (fit), increases the surface area to
dissipate forces, and helps to guide the motion
between joints.
The fundamental movements that exists between
curved joint surfaces are as follows:
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FUNDAMENTAL
ARTHROKINEMATIC MOVEMENTS
Definition
Analogy
Roll (rock)
Multiple points along A tire rotating on a
one rotating articular stretch of pavement
surface contact
multiple points on
another articular
surface
Slide (glide)
A single point on one
articular surface
contacts multiple
points on another
articular surface
A non-rotating tire
skidding across a
stretch of icy
pavement
Spin
A single point on one
articular surface
rotates on a single
point on another
articular surface
A toy top rotating on
one spot on the floor
Dr. Michael P. Gillespie
Movement
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ARTHROKINEMATICS
Dr. Michael P. Gillespie
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ARTHROKINEMATIC PRINCIPLES OF
MOVEMENT
For a convex-on-concave surface movement, the
convex member rolls and slides in opposite
directions.
 For a concave-on-convex surface movement, the
concave member rolls and slides in similar
directions.
 Manual therapy techniques can take advantage
of these principles by applying external forces to
assist or guide the natural arthrokinematics of
the joint.
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Dr. Michael P. Gillespie
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CLOSE-PACKED AND LOOSEPACKED POSITIONS AT A JOINT
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Close-packed position.
The pair of articular surfaces within most joints “fits” best in
only one position, which is usually at the end of the range of
motion.
 This position of maximal congruency is referred to as the
joint’s close-packed position.
 In this position, most ligaments and parts of the capsule are
pulled taut, which provides stability.
 Accessory movements are minimal.
 Used in standing.
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Dr. Michael P. Gillespie
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Loose-packed position.
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All positions other than a joint’s close-packed position are
referred to as the joint’s loose-packed positions.
The ligaments and capsule are relatively slackened.
There is an increase in accessory movements.
The joint is least congruent near its midrange.
Biased towards flexion.
Used during long periods of immobilization.
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KINETICS
Kinetics is the branch of study of mechanics
that describes the effect of forces on the body.
 A force is a push or pull that can produce, arrest,
or modify movements.
 Forces either move or stabilize the body.
 Newton’s 2nd law of motion states that the force
(F) is the product of the mass (m) times the
acceleration (a) of the mass. F=ma
 The standard international unit of force is the
newton (N): 1 N = 1 kg x 1 m/sec2. The Englosh
equivalent of the newton is the pound (lb): 1 lb =
1 slug x 1 ft/sec2 (4.448 N = 1 lb).
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Dr. Michael P. Gillespie
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MUSCULOSKELETAL FORCES
Load – A force that acts on the body is often
referred to generically as a load.
 Forces or loads that move, fixate, or otherwise
stabilize the body also have the potential to
deform and injure the body.
 Any tissue weakened by disease, trauma, or
prolonged disuse may not be able to adequately
resist the application of loads placed upon it.
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Dr. Michael P. Gillespie
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LOADS FREQUENTLY APPLIED TO
THE MUSCULOSKELETAL SYSTEM
Tension
 Compression
 Bending
 Shear
 Torsion
 Combined loading
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Dr. Michael P. Gillespie
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LOADING MODES
Dr. Michael P. Gillespie
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LOADS FREQUENTLY APPLIED TO
THE MUSCULOSKELETAL SYSTEM
Dr. Michael P. Gillespie
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LOADS FREQUENTLY APPLIED TO
THE MUSCULOSKELETAL SYSTEM
Dr. Michael P. Gillespie
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STRESS-STRAIN RELATIONSHIP OF
TISSUES
Stress is applied to a tissue with a resultant
strain on that tissue.
 Initially, the tissue will respond with an elastic
strain. It will stretch; however, it can return to
its prior state.
 With continued stress, the tissue will eventually
reach a yield point. The tissue will begin to
undergo plastic deformation.
 If the stress continues, the tissue will reach an
ultimate failure point. At this point, the tissue
completely separates and loses its ability to hold
any level of tension.
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Dr. Michael P. Gillespie
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STRESS-STRAIN RELATIONSHIP OF
TISSUES
Dr. Michael P. Gillespie
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INTERNAL & EXTERNAL FORCES

Internal forces are produced from structures
within the body.

External forces are produced by forced acting
from outside the body.
Dr. Michael P. Gillespie
Active forces are generated by stimulated muscle.
 Passive forces are generated by tension in stretched
periarticular tissues (intramuscular connective
tissues, ligaments, and joint capsules).

Gravity pulling on the mass of a body segment.
 An external load.
 Physical contact.
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INTERNAL & EXTERNAL FORCES
Dr. Michael P. Gillespie
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VECTORS
Forces are depicted by arrows that represent a
vector.
 A vector is a quantity that is completely specified
by its magnitude and direction.
 In order to completely identify a vector in a
biomechanical analysis, its magnitude, spatial
orientation, direction, and point of application
must be known.
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Dr. Michael P. Gillespie
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MUSCLE AND JOINT INTERACTION
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Dr. Michael P. Gillespie
Muscle and joint interaction refers to the
overall effect that a muscle force may have on a
joint.
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TYPES OF MUSCLE ACTIVATION

Isometric activation
A muscle is producing a pulling force while maintaining a constant
length. Greek isos (equal) and metron (measure or length).
 The internal torque is equal to the external torque.
 There is no muscle shortening or rotation at the joint.
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Concentric activation
A muscle produces a pulling force as it contracts (shortens).
Concentric means “coming to the center”.
 The internal torque exceeds the external torque.
 The contracting muscle creates a rotation of the joint in the direction
of the contracting muscle.
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Dr. Michael P. Gillespie
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Eccentric activation
A muscle produces a pulling force as it is being elongated by another
more dominant force. Eccentric means “away from the center”.
 The external torque exceeds the internal torque.
 The joint rotates in the direction dictated by the larger external
torque.
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CONTRACTION
The term contraction is often used synonymously
with the term activation, regardless of whether
or not the muscle is really shortening,
lengthening, or remaining at a constant length.
 The term contract literally means to be “drawn
together”.
 Technically, contraction of a muscle occurs
during concentric activation only.
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Dr. Michael P. Gillespie
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