Joints

• Fibrous joints are immovable and are connected by fibrous connective tissue.
• Pivot joint:

  • Structure: One bone articulates within a ring made of ligaments that secures it to another bone
  • Function: Only the first bone is moving, rotating
  • Location:
  • Atlantoaxial joint (Between the C1 & C2 vertebra)
  • Proximal radioulnar joint (the head of the radius rotates inside a ligamentous ring securing it to the ulna)
• Hinge Joint:

  • Structure: Between the rounded shape of one bone and trough-shaped of another bone, bone articulates like a hinge
  • Function: Flexion and extension
  • Location: Ankle, knee, interphalangeal, elbow joints
• Saddle Joint:

  • Structure: Between 2 bones that are saddle-shaped, each bone has articular surfaces that are concave in one direction and convex in the other
  • Function: Allows range of motion in 2 different axes
  • Location: Carpometacarpal joint of the thumb (between one of the bones on the wrist and the first metacarpal bone)
• Plane Joint:

  • Structure: Between 2 flat surfaces of 2 or more bones, they glide against each other
  • Function: Flexion, extension, inversion, and eversion
  • Location:
  • Intercarpal joints between the bones of the wrist
  • Intertarsal joint between the bones of the ankle
• Condyloid Joint:

  • Structure: Between the rounded oval surface of one bone and shallow oval depression of another bone
  • Function: Abduction, adduction, flexion, extension, circumduction
  • Location:
  • Radiocarpal joints (between the radius and the bones of the wrist)
  • Metacarpophalangeal joints (between the metacarpal bones of the palm and the first portion of fingers)
• Ball and Socket Joint:

  • Structure: Spherical head of one bone articulates within the cup-like or socket-shaped surface of another
  • Function: Multiple axial planes, abduction, adduction, flexion, extension, internal and external rotation, circumduction
  • Location: Glenohumeral (shoulder), Hip joints
• Cartilaginous Joints:

  • Types:
  • Synchondroses: bones connected by hyaline cartilage
  • Symphyses: bones connected by fibrocartilage
  • Function: Typically immobile, slightly moveable for flexion and extension
  • Location:
  • Epiphyseal plates (between first rib and the manubrium of the sternum)
  • Pubic symphysis
• Fibrous Joints:

  • Structure: Made of dense fibrous connective tissue
  • Function: Provide stability and strength, no movement
  • Location: Skull structures, Syndesmoses (distal tibia and fibula)
• Types of Body Movements:

  • Rotation: Turning or twisting a body part around its own axis
  • Circumduction: Circular movement
  • Abduction: Moving a body part away from the body's midline
  • Adduction: Bringing a body part closer to the body's midline
  • Depression: Moving a body part downward
  • Elevation: Lifting or moving a body part upward
  • Flexion: Bending a joint, bringing parts closer
  • Extension (and hyperextension): Straightening a joint, moving parts away
  • Plantar Flexion: Pointing the toes downward
  • Dorsiflexion: Lifting the toes upward
• Cartilages:

  • Articular (Hyaline) cartilage: smooth, frictionless surface for joints, shock absorber, structural support
  • Elastic cartilage: elasticity, resilience, flexibility
  • Fibrocartilage: support, rigidity, cushioning, shock absorption
• Cruciate/Collateral Ligament:

  • Anterior Cruciate Ligament (ACL): prevents excessive anterior forward movement of the tibia to femur, controls rotational stability in the knee
  • Posterior Cruciate Ligament (LCL): prevents excessive posterior backward movement of the tibia to the femur, controls rotational stability in the knee
  • Medial Collateral Ligament (MCL): resists valgus stress, provides medial stability on the inner side of the knee
  • Lateral Collateral Ligament (LCL): resists Varus stress, provides lateral stability on the outer side of the knee
• Another term for synovial joint is Diarthroses
• Pivot joints allow for rotation only.
• Another term for cartilaginous joints is amphiarthroses
• Another term for fibrous joints is synarthroses
• ACL - Lachman test:

  • Procedure: stabilize the thigh and try to move the tibia anterior relative to the femur by grabbing the tibia anteriorly
  • Positive sign of ACL injury: no firm end point + discomfort
• ACL - Pivot shift test:

  • Procedure: take the heel and put the leg into internal rotation, apply valgus stress, take the knee from full extension to flexion
• MCL - Valgus stress test:

  • Procedure: first in extension then apply valgus force, then at 30° flexion apply valgus force
• Meniscus tests:

  • Full flexion, valgus stress, and heel rotation or full flexion, internal rotation, and varus force, moving from flexion to extension
• ACL - AP draw test:

  • Procedure: sit on the foot and pull (the back of the knee) anteriorly
• Meniscus - Grind test: lies on stomach, put leg into 90° flexion, stabilize femur, apply axial load, move leg into internal and external rotation 
• Valgus


  pushing towards the center of the body 
• Varus


  Pushing away from the center of the body