Skeletal Articulations

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Skeletal Articulations

• Anatomical Kinesiology

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Classification of Joints

• Synarthroses (immovable) (syn together, arthron
  joint) Fibrous joints can absorb shock but
  permit little or no movement. Sutures and
  Syndesmoses.

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Classification of Joints

• Amphiarthroses (slightly immovable) (amphi on
  both sides) Cartilaginous joints absorbs shock
  permits limited movement. Synchrondrosis,
  Symphyses.

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Classification of Joints

• Diarthroses or synovial (freely movable)
  (diarthroses through joint indicating only
  slight limitations to movement capability).

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Characteristics of Diarthrodial Joints

• Articular cavity is present.
• Articular cartilage covers articulating bone
  surfaces.
• Joint is enclosed in an articular capsule

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Characteristics of Diarthrodial Joints

• The joint is lined with synovial membrane that
  secretes synovial fluid which lubricates
  nourishes.

• Whenever soft structures are frequently submitted
  to frictional rubbing on bony protuberance, may
  find bursae, small capsules lined with synovial
  membrane and filled with synovial fluid that
  cushion bones they separate.

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Characteristics of Diarthrodial Joints

• Another structure often associated with
  diarthrodial joints is tendon sheath. Tendons
  surrounded by cylindrical sac consisting of two
  layers of synovial membrane enclosing a cavity
  with synovial fluid.

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Categories of Diarthrodial Joints

• Gliding, Arthrodial, Plane.
• Nonaxial Allows sliding Articulating
  surfaces are nearly flat. Intermetatarsal,
  intercarpal, intertarsal, facet joints of
  vertebrae.

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Categories of Diarthrodial Joints

• Hinge, Ginglymus.
• Uniaxial Allows flexion and extension One
  articulating surface is spool-like (convex),
  other is concave. Elbow, interphalangeal,
  talocrural joint of the ankle.

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Categories of Diarthrodial Joints

• Pivot, Screw, Trochoid.
• Uniaxial Allows rotation Peglike pivot, as in
  joint between atlas and axis, or two long bones
  rolling around one another.

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Categories of Diarthrodial Joints

• Condyloid, Ovoid, Ellipsoid.
• Biaxial Movement forward backward and side to
  side Oval convex fits into reciprocal concave.
  2nd thru 5th metacarpal-phalangeal joints.

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Categories of Diarthrodial Joints

• Saddle, Sellar.
• Biaxial Permits flexion, extension, abduction,
  adduction, and circumduction both ends of convex
  surface tipped to fit into reciprocal concave
  surface. Thumb.

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Categories of Diarthrodial Joints

• Ball Socket, Spheroidal, Enarthrodial.
• Triaxial Spherical head of one bone fits into
  cup of the other bone. Hip, Shoulder.

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Categories of Diarthrodial Joints
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Planes of Motion

• Sagittal

2. Frontal
3. Transverse
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Articular Cartilage

• Functions 1) spreads loads at joint over wider
  area, and 2) allows movement with minimal
  friction and wear
• Characteristics soft, porous,
• and permeable tissue that is
• hydrated.

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Articular Fibrocartilage

• Possible Roles distribution of loads,
  improvement of fit, limitation of translation,
  protection of periphery of joint, lubrication,
  shock absorption.
• Tissue characteristics
• soft-tissue discs or
• menisci

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Articular Connective Tissue

• Tendons extensible, slightly elastic, not
  contractile
• Connect muscles to bones

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Articular Connective Tissue

• Ligaments extensible, slightly elastic, not
  contractile
• Connect bones to bones

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Joint Stability

• Shape of Articulating Bone Surfaces.
• Arrangement of Ligaments and Muscles.
• Other Connective Tissues.

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Shape of ArticulatingBone Surfaces
Although most joints have reciprocally shaped
articulating surfaces, these surfaces are not
symmetrical and there is one position of best fit.
Close-packed joint orientation contact between
surfaces is maximum.
Loose-packed any other joint orientation.
Ligaments tend to be slack.
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Arrangement of Ligaments and Muscles
Ligaments are discrete from joint capsule tough,
flexible, and somewhat elastic. Stress, if
prolonged, may cause stretching. If
overstretched, may never regain normal length.
Muscle arrangement usually pulls bones of joint
together, enhancing joint stability.
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Other Connective Tissue

• White fibrous connective tissue known as fascia
  surrounds muscles and bundles of fibers within
  muscle. The iliotibial band is fascia that
  crosses the lateral aspect of the knee.
• Skin on the exterior of body contributes to joint
  integrity.

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Joint Mobility

• Joint flexibility a term representing the
  relative range of motion allowed at a joint.
• Range of motion (ROM) angle through which a joint
  moves from
• anatomical position to the
• extreme limit of segment
• motion in a particular
• direction.

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Joint Mobility

• By definition, a joint is mobile. However, a
  joint must be sufficiently stable.
• Every joint finds a balance between mobility and
  stability.
• The more mobile a joint is, the less stable it
  is.
• Therefore mobility and stability are antagonistic
  concepts more of one means less of the other.

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Joint Mobility
Joint ROM is measured directionally in units of
degrees.
Flexion is from starting position to maximal
flexed position.
Extension is return to anatomical position.
Hyperextension is movement beyond the starting
point.
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Joint Mobility
Methods to Measure Joint ROM
Double armed goniometer one arm stationary
other moveable.
Leighton flexometer device attaches to a moving
body segment.
Electrogoniometer potentiometer located at axis
of rotation sends electrical current to recorder
as change joint position.
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Leighton flexometer
The Leighton Flexometer is a highly accurate, 360
degree, gravity type goniometer designed
specifically for measuring the flexibility of
major segmental movements of the body as an
aspect of fitness, rehabilitation and athletic
performance. It has a fully adjustable strap
attached allowing it to be fixed to virtually any
part of the body to provide many different
measurements. The unit consists of a twin
rotating dial construction with ingenious locking
mechanisms to ensure easy and accurate
measurements.
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Electrogoniometer
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Flexibility Injury
Is heightened when joint flexibility is extremely
high, extremely low, or significantly imbalanced
between dominant and nondominant sides of body.
Risk of Injury
Reduced flexibility with aging is primarily a
function of decreased activity.
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Techniques for Increasing Joint Flexibility

• Stretch (myotatic) Reflex
• Muscle spindles stimulated by muscle lengthening
  (passive stretch) cause muscle to contract when
  stretched
• Golgi tendon organs stimulated by active muscle
  contraction or passive muscle stretch cause
  relaxation after 5 to10 seconds of passive
  stretch
• Reciprocal inhibition antagonist muscle relaxes
  when the agonist contracts.
• Autogenic Inhibition antagonist muscle relaxes
  following its own contraction

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Stretching
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Common Joint Injuries

• Sprain stretch or tear of ligaments and
  connective tissues.
• Strain stretch or tear of muscle or tendon
• Dislocation displacement of articulating bones.
• Bursitis frictional irritation inflammation of
  bursae.

• Arthritis pathology involving joint
  inflammation.
• Rheumatoid Arthritis autoimmune disorder,
  thickening synovial membranes.
• Osteoarthritis non-inflammatory degenerative
  arthritis.