Courtesy: Sports Science Solutions, Lecture on Classification of Joints

 

Classification and Function of Joints

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Overview

• Joints (articulations) are points where two or more bones meet
• Functions:
  • Allow movement
  • Provide stability

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Basis of Classification

• Structure (type of tissue connecting bones)
• Function (degree of movement allowed)

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Skeletal System and Joints

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Total Bones

• 206 bones

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Divisions of Skeleton

Axial Skeleton (80 bones)

• Skull
• Vertebral column
• Ribs
• Sternum

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Appendicular Skeleton (126 bones)

• Upper limbs
• Lower limbs
• Shoulder girdle
• Pelvic girdle

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 Joints are formed where these bones meet

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Structural Classification of Joints

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Types

• Fibrous joints
• Cartilaginous joints
• Synovial joints

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1. Fibrous Joints

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Characteristics

• Connected by fibrous tissue
• Minimal or no movement

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Types

Suture

• Short fibrous connections
• Found in skull
• Movement: None (synarthrotic)

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Syndesmosis

• Connected by ligaments
• Example:
  • Distal tibiofibular joint
• Movement: Slight (amphiarthrotic)

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Gomphosis

• Peg-in-socket joint
• Example:
  • Tooth in alveolar socket
• Movement: None (synarthrotic)

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2. Cartilaginous Joints

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Characteristics

• Bones connected by cartilage

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Types

Synchondrosis

• Hyaline cartilage
• Examples:
  • Growth plate
  • First rib–sternum
• Movement: None

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Symphysis

• Fibrocartilage
• Examples:
  • Intervertebral discs
  • Pubic symphysis
• Movement: Slight

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3. Synovial Joints

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Characteristics

• Joint cavity present
• Contains synovial fluid
• Freely movable

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Function

• Diarthrotic (freely movable)

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Types of Synovial Joints

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Plane Joint

• Gliding movement
• Example:
  • Intercarpal joints

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Hinge Joint

• Movement in one plane
• Example:
  • Elbow joint

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Pivot Joint

• Rotation around axis
• Example:
  • Proximal radioulnar joint

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Condyloid Joint

• Oval surface articulation
• Example:
  • Metacarpophalangeal joints

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Saddle Joint

• Concave + convex surfaces
• Example:
  • Thumb carpometacarpal joint

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Ball and Socket Joint

• Multidirectional movement
• Examples:
  • Shoulder joint
  • Hip joint

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Functional Classification of Joints

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1. Synarthrotic

• No movement
• Examples:
  • Skull sutures
  • Gomphosis

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2. Amphiarthrotic

• Slight movement
• Examples:
  • Distal tibiofibular joint
  • Pubic symphysis

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3. Diarthrotic

• Freely movable
• Examples:
  • Synovial joints

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Axis-Based Classification of Synovial Joints

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Nonaxial

• No rotation around axis
• Example:
  • Plane joints

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Uniaxial

• Movement in one axis
• Examples:
  • Hinge joints
  • Pivot joints

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Movements

• Flexion/extension
• Rotation

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Biaxial

• Movement in two axes
• Examples:
  • Condyloid
  • Saddle joints

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Movements

• Flexion/extension
• Abduction/adduction
• Circumduction

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Multiaxial

• Movement in three axes
• Example:
  • Ball and socket joints

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Movements

• Flexion/extension
• Abduction/adduction
• Circumduction
• Rotation

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Examples of Joint Classification

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Distal Tibiofibular Joint

• Structural: Fibrous
• Type: Syndesmosis
• Function: Slight movement

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Pubic Symphysis

• Structural: Cartilaginous
• Type: Symphysis
• Function: Slight movement

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Shoulder Joint

• Structural: Synovial
• Type: Ball and socket
• Function: Freely movable
• Axis: Multiaxial

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Summary Points

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• Joints are classified by:
  • Structure
  • Function
• Structural types:
  • Fibrous
  • Cartilaginous
  • Synovial
• Functional types:
  • Synarthrotic
  • Amphiarthrotic
  • Diarthrotic
• Synovial joints further classified by:
  • Axis of movement