Joints in the Human Body System

Study Outline for Chapter 9: Joints

Key Terms

  • Classification of Joints: Understanding the types of joints in the human body is essential for studying biomechanics and anatomy.
    • Fibrous Joints:
    • Definition: Fixed joints that are bound together by collagen fibers.
    • Cartilaginous Joints:
    • Definition: Semi-movable joints that are connected by cartilage.
    • Synovial Joints:
    • Definition: Freely movable joints that allow for a wide range of motion.

Osteoarthritis and Synovial Joints

  • Bursae in Synovial Joints:
    • Definition: Small sacs filled with synovial fluid that cushion and reduce friction between joints.

Types of Synovial Joints (Refer to page 141)

  • Understanding the characteristics and examples of each type of synovial joint is crucial.
    1. Ball and Socket Joints:
    • Characteristics: Allow the widest range of motion.
    • Examples: Shoulder and hips.
    1. Pivot Joints:
    • Characteristics: Allow rotation.
    • Example: Joint in the neck (head rotation).
    1. Hinge Joints:
    • Characteristics: Allow back and forth movement (flexion and extension).
    • Example: Elbow joint.
    1. Saddle Joints:
    • Characteristics: Permit back and forth and side to side movement.
    • Example: Joint at the base of the thumb.
    1. Condyloid Joints:
    • Characteristics: Allow movement side to side.
    • Example: Wrist joint.
    1. Gliding Joints:
    • Characteristics: Allow bones to slide over each other.
    • Example: Joints in the feet.

Movement of Synovial Joints

  • Understanding the movements involved in synovial joints helps to analyze joint mechanics.
    1. Flexion and Extension:
    • Definition: Bending and straightening of a joint.
    1. Abduction and Adduction:
    • Definition: Movement away from (abduction) and toward (adduction) the midline of the body.
    1. Circumduction:
    • Definition: Circular motion of a limb.
    1. Supination and Pronation:
    • Definitions:
      • Supination: Turning the palm upward.
      • Pronation: Turning the palm downward.
    1. Rotation:
    • Definition: Bone spins either toward or away from the midline.
    1. Inversion and Eversion:
    • Definitions:
      • Inversion: Movement of the sole toward the midline.
      • Eversion: Movement of the sole away from the midline.
    1. Protraction and Retraction:
    • Definitions:
      • Protraction: Moves body parts forward.
      • Retraction: Moves body parts backward.

Key Synovial Joints

  • Understanding key joints helps to analyze common injuries and their implications.
    1. Shoulder:
    • Type: Ball and socket joint.
    • Common Issue: Dislocations (most commonly occurs).
    1. Elbow:
    • Type: Hinge joint.
    • Function: Allows flexion and extension.
    1. Knee:
    • Type: Modified hinge joint.
    • Function: Allows flexion, extension, and slight rotation.
    • Knee Injuries:
      • Anterior Cruciate Ligament (ACL): Common sports injury.
    1. Hip:
    • Type: Ball and socket joint.
    • Characteristics: Very stable due to deep acetabulum socket.

Arthritis and Surgical Replacement

  • Rheumatoid Arthritis:
    • Definition: Inflammation of a joint leading to pain, swelling, and stiffness.
  • Arthroplasty:
    • Definition: Surgical procedure that replaces a diseased joint with an artificial device or prosthesis.
    • Commonly performed on the hip and knee joints.