Joints or Articulations

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Chapter 8

• Joints or Articulations

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Why do we need them?

• Articulations are junctions between bones
• They bind parts of skeletal system together
• Make bone growth possible
• Permit parts of the skeleton to change shape
  during childbirth
• Enable body to move in response to skeletal
  muscle contraction

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Classification of Joints-Structural and Functional

• Fibrous Joints-lack a synovial cavity and permit
  little to no movement
• dense connective tissues connect bones
• between bones in close contact

• synarthrotic
• immovable
• amphiarthrotic
• slightly movable
• diarthrotic
• freely movable

• Cartilaginous Joints-lack a synovial cavity and
  allow little or no movement
• hyaline cartilage or fibrocartilage connect
  bones form a tight connection

• Synovial Joints-have a joint cavity
• most complex
• allow free movement

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Fibrous Joints

• 3 Types
• Syndesmosis
• Suture
• Gomphosis

• Syndesmosis
• long fibers connect bones
• amphiarthrotic
• distal ends of tibia and fibula

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Fibrous Joints

• Suture
• between flat bones (skull)
• synarthrotic
• thin layer of connective tissue connects bones
• Metopic suture of frontal bone usually fuses
  completely

• Gomphosis
• cone-shaped bony process in a socket
• tooth in jawbone
• synarthrotic

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Cartilaginous Joints

• 2 Types
• Synchondrosis
• Symphysis

• Synchondrosis
• bands of hyaline cartilage unite bones
• epiphyseal plate (temporary)
• between manubrium and first rib
• synarthrotic (immoveable)

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Cartilaginous Joints

• Symphysis
• pad of fibrocartilage between bones
• pubis symphysis
• joint between bodies of vertebrae
• amphiarthrotic

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Synovial Joints

• diarthrotic
• joint cavity allows joint to
• move freely
• synovial fluid-reduce friction, absorb
• shocks, supply oxygen and remove waste
• from chondrocytes
• joint capsule
• synovial membrane-inner layer
• of the articular capsule
• Articular cartilage covers ends
• bursae-reduce friction, cushion movement

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Types of Synovial Joints

• Condyloid Joint
• between metacarpals and phalanges
• Oval shaped projection fits into oval shaped
  depression

• Ball-and-Socket Joint
• hip
• shoulder
• Permit multiaxial movement

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Types of Synovial Joints

• Gliding Joint or Planar Joints
• between carpals
• between tarsals
• Articular surfaces are flat to slightly
• curved

• Hinge Joint
• elbow
• between phalanges

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Types of Synovial Joints

• Pivot Joint
• between proximal ends of radius and ulna and
  between axis and atlas

• Saddle Joint
• between carpal and metacarpal of thumb
• Modified condylar joint

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Types of Joint Movements

• abduction- movement away from midline
• Adduction-movement toward midline
• dorsiflexion-bend the foot at the ankle (stand
  on heels)
• Plantarflexion-bend foot at ankle toward inferior
  (stand on toes)
• flexion-decrease the angle
• Extension-increase angle of joint
• Hyperextension-continue extension beyond
  anatomical position

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Types of Joint Movements

• rotation-bone turns on longitudial axis
• Circumduction-one end remains stationary
• supination palm is up (hold soup)
• pronation-palm is down or facing the rear

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Types of Joint Movements

• eversion-turning sole of foot laterally
• inversion-turning sole medially
• protraction-/retraction
• elevation/depression

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Shoulder Joint

• ball-and-socket
• head of humerus and glenoid cavity of scapula
• loose joint capsule
• 4 bursae reduce friction-look up names
• ligaments prevent displacement
• very wide range of movement
• Rotator cuff- supraspinatus, infraspinatus, teres
  minor, subscapularis, work together to join
  scapula to humerus

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Shoulder Joint
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Elbow Joint

• hinge joint
• trochlea of humerus
• trochlear notch of ulna
• gliding joint
• capitulum of humerus
• head of radius
• flexion and extension
• many reinforcing ligaments
• Including radial collateral ligament
• and ulnar collateral ligament
• stable joint

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Elbow Joint
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Hip Joint

• ball-and-socket joint
• head of femur
• acetabulum
• Acetabular labrum is a fibrocartilage rim that
  increases depth of socket
• heavy joint capsule
• many reinforcing ligaments-like ischiofemoral
  and iiofemoral ligament
• less freedom of movement than shoulder joint

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Hip Joint
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Knee Joint

• largest joint and most complex
• medial and lateral condyles of distal end of
  femur
• medial and lateral condyles of proximal end of
  tibia
• femur articulates anteriorly with patella
• modified hinge joint
• flexion/extension/little rotation
• strengthened by many ligaments and tendons-PCL,
  ACL, tibial collateral ligament, fibular
  collateral ligament,
• menisci separate femur and tibia
• bursae include pre-patellar bursae which is
  often damaged when you bump the anterior knee

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Knee Joint
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Life-Span Changes

• Joint stiffness is an early sign of aging
• Regular exercise can prevent stiffness
• Fibrous joints first to strengthen over a
  lifetime
• Changes in symphysis joints of vertebral column
  diminish flexibility and decrease height
• Synovial joints lose elasticity

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Clinical Application

• Sprains- damage to cartilage, ligaments, or
  tendons
• associated with joints
• forceful twisting of joint http//physicaltherapy
  .about.com/od/sportsinjuries/a/strainvssprain.htm
  for difference between sprain and strain

Bursitis- inflammation of a bursa caused by
overuse of joint

• Arthritis-inflamed, swollen, painful joints
• Rheumatoid Arthritis-RA, autoimmune disease
• Osteoarthritis or OA-most common, wear and tear
• Gout-often strikes big toe, peanuts can
  aggravate this, excess uric acid
• crystals deposit in joints

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Disorders

• Cartilage injury-usually require surgery
• Dislocation (luxation)-forced bone out of
  alignment, usually downward displacement
• Partial dislocation is subluxation
• Bursitis-also known as housemaids knee, tennis
  elbow, student elbow (olecranon bursitis)
• Tendonitis-inflammation of tendon sheath, same
  type symptoms as bursitis