Arthrology and Classification of Joints

Types of Joints

• Diarthroses predominate in the limbs and are also called synovial joints or diarthrodial joints.

Synovial Joints

• Plane: Flat articular surfaces that allow for short gliding movements.
• Hinge: Cylindrical end of one bone fits into the trough of another bone, allowing for angular movement in one plane.
• Pivot: Rounded end of one bone fits into a ring formed by another bone, allowing for rotation.
• Condyloid: Egg-shaped articular surface fits into the oval concavity in another, allowing for flexion, extension, abduction, and adduction.
• Saddle: Has both convex and concave areas, allowing for flexion, extension, abduction, adduction, and circumduction.
• Ball and socket: Spherical head of one bone fits into a round socket in another, allowing for the most freedom of movement, including flexion, extension, abduction, adduction, circumflexion, and rotation.

Classification of Joints

• Classification based on function: Synarthroses, Amphiarthroses, Diarthroses.
• Classification based on structure: Fibrous joints, Cartilaginous Joints, Synovial Joints.

Classification of Joints by Movement/Function

• Synarthroses: immovable joints (sutures).
• Amphiarthroses: slightly movable joints (cartilaginous connection).
• Diarthroses: freely movable joints (synovial).

Classification of Joints by Structure

• Fibrous joints: composed of fibrous (inelastic) connective tissue, non-movable.
• Cartilaginous Joints: formed by cartilage, semimovable.
• Synovial Joints: movable joints, contain a joint capsule of synovial membrane.

Synovial Joints

• No direct union between the bone ends, joint cavity inside the articular capsule is filled with synovial fluid.
• Extracapsular ligaments hold the bones in position, Intracapsular ligaments control degree and direction of movement.
• Articular surface is very smooth and covered with cartilage called hyaline or articular cartilage.

Arthrology

• Arthrology is the scientific study of joints and articulations.