Joints and Movements

Joints

Classification of Joints

  • Articulation

    • Site where two or more bones meet.

  • Functions of Joints

    • Give skeleton mobility.

    • Hold skeleton together.

  • Two Classifications

    • Functional Classification

    • Based on degree of movement allowed.

      • Synarthroses: Immovable joint.

      • Amphiarthroses: Slightly movable.

      • Diarthroses: Freely movable.

    • Structural Classification

    • Based on type of connective tissue that joins bones together:

      • Fibrous Joints: No movement (synarthroses).

      • Cartilaginous Joints: Allow very little motion (amphiarthroses).

      • Synovial Joints: Freely movable joints (diarthroses).

Structural Classification of Joints

  • Fibrous Joints

    • Sutures: Found only in the skull; toothlike projections from adjacent bones interlock with each other.

    • Syndesmoses: Joints in which ligaments connect two bones.

    • Gomphoses: Between root of a tooth and the alveolar process of the mandible or maxilla.

  • Cartilaginous Joints

    • Synchondroses: Hyaline cartilage present between articulating bones.

    • Symphyses: Joints where a pad or disk of fibrocartilage connects two bones (e.g., pubic symphysis).

  • Synovial Joints

    • Structures:

    • Joint Capsule: Sleevelike casing around ends of bones binding them together.

    • Synovial Membrane: Lines joint capsule and secretes synovial fluid.

    • Articular Cartilage: Hyaline cartilage covering articular surfaces of bones.

    • Joint Cavity: Small space between articulating surfaces of two bones.

    • Menisci: Pads of fibrocartilage located between articulating bones.

    • Ligaments: Strong cords of dense white, fibrous tissue holding bones together.

    • Bursae: Synovial membranes filled with fluid, cushioning joints and facilitating tendon movement.

Types of Synovial Joints

  • Nonaxial Joints: Flat articular surfaces (e.g., gliding joints).

  • Uniaxial Joints: Movement around one axis (e.g., hinge joints like elbow and knee, pivot joints).

  • Biaxial Joints: Movement around two perpendicular axes (e.g., saddle joints like the thumb, condyloid joints).

  • Multiaxial Joints: Movement around three or more axes (e.g., ball-and-socket joints like shoulder and hip).

Measurements of Range of Motion (ROM) at Synovial Joints

  • Range of Motion Assessment: Used to determine the extent of joint injury.

    • Measured actively or passively using a goniometer.

Angular Movements

  • Flexion: Decreases the angle between bones, bending part on another.

  • Extension: Increases the angle between bones, returning a part to anatomical position.

  • Hyperextension: Extending part beyond anatomical position.

  • Plantar Flexion: Increases angle between foot and leg.

  • Dorsiflexion: Decreases angle between foot and leg.

  • Abduction: Moves part away from median plane.

  • Adduction: Moves part toward median plane.

Circular Movements

  • Rotation: Pivoting a bone on its own axis.

  • Circumduction: Moving a part so that its distal end moves in a circle.

  • Supination: Turning palm side up.

  • Pronation: Turning palm side down.

Special Movements

  • Inversion: Turning sole of foot inward.

  • Eversion: Turning sole of foot outward.

  • Protraction: Moves a part forward.

  • Retraction: Moves a part backward.

  • Elevation: Moves a part up.

  • Depression: Lowers a part.

Arthritis

  • Introduction: Over 100 different types of inflammatory or degenerative diseases damaging joints.

  • Symptoms: Pain, stiffness, swelling of joint.

  • Acute Forms: Caused by bacteria, treated with antibiotics.

  • Chronic Forms: Include osteoarthritis, rheumatoid arthritis, gouty arthritis.