Joints

• Joints

  • The site which 2 or more bones meet
  • Joint types:
  • Fixed/fibrous
  • Cartilaginous
  • Synovial
• Fixed/Fibrous Joints

  • No movement occurring at joint.
  • Bones held in place by fibrous connective tissue
  • Very strong and difficult to damage
  • Skull, teeth and jaw
• Cartilaginous

  • Held in place by cartilage allowing slight movement.
  • Pubic symphysis, vertebral joints, ribs and sternum.
• Synovial

  • Freely moveable, amount of movement limited by ligaments, muscles and tendons.
  • Commonly injured
  • Six types:
  • Ball and socket
  • Hinge
  • Pivot
  • Gliding
  • Saddle
  • Condyloid ellipsoid
• Ball and Socket

  • Spherical head of one bone fits into a socket
  • Movement - flexion and extension, abduction and adduction, rotation.
  • Shoulder and hip joint.
• Hinge

  • The convex surface of one bone fits into the concave surface of another
  • Movement - in one plane only. Flexion/extension
  • Elbow/knee, ankle, phalanges (fingers).
• Pivot

  • Rounded, pointed or conical end of one bone articulates with a ring of bone and ligament.
  • Movement - rotation
  • Atlas/axis (vertebra) and radius/ulna (forearm)
• Gliding

  • Two bone with relatively flat surfaces in contact with each other.
  • Movement - side to side and back and for the movement.
  • Carpal bones (hand), tarsal bones (foot), sternum/clavicle and scapula/clavicle.
• Saddle

  • Thumb joins the palm of the hand
  • Bones are saddle shaped (convex/concave)
  • Movement - side to side and back and forth movement.
• Condyloid/ellipsoid

  • Slightly convex bone fits into a slightly concave bone
  • Movement - in 2 directions only (up and down or side to side)
  • Radius/Carpals/phalanges (hand/fingers)
• Synovial Joint Structure

  • Freely moveable
  • Synovial cavity - space between articulating surface
  • Articular cartilage on the bone surfaces.
• • Articular capsule - 2 layered capsule enclosing the joint
  • Fibrous capsule - outer layer, consisting of dense fibrous connective tissue.
  • Attached to the periosteum of the articulating bones
  • Flexible to permit movement yet strong to resist dislocation.
• • Synovial membrane - inner layer, loose connective tissue.
  • Inner surface is well supplied with blood capillaries.
  • Lines entire joint cavity except articular cartilage.
• • Articular discs - fibrocartilage discs dividing the synovial cavity into 2.
  • Knee - meniscus
• • Synovial fluid - secreted by synovial membrane and fills cavity.
  • Joint lubrication
  • Nourishes articular cartilage
  • Phagocytic cells remove micro-organisms and debris from wear and tear.
• • Accessory ligaments - hold bones together
  • Bursae - little sacs of synovial fluid
  • Positioned to prevent friction between a bone and ligament/tendon or bone and skin
• • Flexion - bending. Decreases angle between articulating bones
• • Extension - straightening. Increases angle between articulating bones
• • Abduction - movement away from the midline
• • Adduction - movement towards the midline
• • Rotation - movement of a bone around its long axis.