KINESIOLOGY OF THE MUSCULOSKELETAL SYSTEM

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KINESIOLOGY OF THE MUSCULOSKELETAL SYSTEM

• Dr. Michael P. Gillespie

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KINESIOLOGY

• Kinesis to move
• Logy to study

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VITRUVIAN MAN LEONARDO DA VINCI
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MUSCULORUM CORPORIS HUMANI - BERNHARD SIEGFREID
ALBINUS
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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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TWO TYPES OF MOTION

• 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.
• 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 bodys 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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TYPES OF MOVEMENT

• Active movement movement caused by stimulating
  a muscle.
• Passive movement movement caused by sources
  other than active muscle contraction.
• 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
• 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
  dUnites, the French name.

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COMMON CONVERSIONS BETWEEN UNITS
SI 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
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OSTEOKINEMATICS

• Osteokinematics describes the motion of bones
  relative to the three cardinal (principal) planes
  of the body.
• 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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CARDINAL PLANES OF THE BODY
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A SAMPLE OF COMMON OSTEOKINEMATIC TERMS
Plane 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
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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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DEGREES OF FREEDOM

• 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
• 1. The proximal segment can rotate against the
  relatively fixed distal segment.
• 2. The distal segment can rotate against the
  relatively fixed proximal segment.
• State the bone that is considered the primary
  rotating segment.
• 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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LOWER EXTREMITY OSTEOKINEMATICS

• The lower extremities perform both
  proximal-on-distal 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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DISTAL-ON-PROXIMAL PROXIMAL-ON-DISTAL KINEMATICS
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OPEN AND CLOSED KINEMATIC CHAINS

• 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

• 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
• Roll
• Slide
• Spin

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FUNDAMENTAL ARTHROKINEMATIC MOVEMENTS
Movement Definition Analogy
Roll (rock) Multiple points along one rotating articular surface contact multiple points on another articular surface A tire rotating on a stretch of pavement
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
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ARTHROKINEMATICS
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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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CLOSE-PACKED AND LOOSE-PACKED POSITIONS AT A JOINT

• 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 joints 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.
• Loose-packed position.
• All positions other than a joints close-packed
  position are referred to as the joints
  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.
• Newtons 2nd law of motion states that the force
  (F) is the product of the mass (m) times the
  acceleration (a) of the mass. Fma
• 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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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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LOADS FREQUENTLY APPLIED TO THE MUSCULOSKELETAL
SYSTEM

• Tension
• Compression
• Bending
• Shear
• Torsion
• Combined loading

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LOADING MODES
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LOADS FREQUENTLY APPLIED TO THE MUSCULOSKELETAL
SYSTEM
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LOADS FREQUENTLY APPLIED TO THE MUSCULOSKELETAL
SYSTEM
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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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STRESS-STRAIN RELATIONSHIP OF TISSUES
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INTERNAL EXTERNAL FORCES

• Internal forces are produced from structures
  within the body.
• Active forces are generated by stimulated muscle.
• Passive forces are generated by tension in
  stretched periarticular tissues (intramuscular
  connective tissues, ligaments, and joint
  capsules).
• External forces are produced by forced acting
  from outside the body.
• Gravity pulling on the mass of a body segment.
• An external load.
• Physical contact.

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INTERNAL EXTERNAL FORCES
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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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MUSCLE AND JOINT INTERACTION

• 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.
• 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.
• 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.