Lecture Notes: Classification of Joints

Introduction

• Joints classified based on:
  • Structural characteristics
  • Functional movement

Structural Classification

• Criteria:

  1. Presence or absence of a space: called a synovial cavity
  2. Type of connective tissue binding bones

• Types of Joints:

  1. Fibrous Joint
     • No synovial cavity
     • Bones held by dense irregular connective tissue
  2. Cartilaginous Joint
     • No synovial cavity
     • Bones held by cartilage
  3. Synovial Joint
     • Contains synovial cavity
     • Bones connected by dense irregular connective tissue of an articular (joint) capsule

Functional Classification

• Types of Movement:
  1. Synarthrosis: Immovable joint
  2. Amphiarthrosis: Slightly movable joint
  3. Diarthrosis: Freely movable joint

Focus: Structural Classification of Joints

• Each joint has both structural and functional classifications

Fibrous Joints

• Characteristics:

  • Lacks synovial cavity
  • Bones held together closely by dense irregular connective tissue
  • Permits little to no movement (classified functionally as synarthrosis or amphiarthrosis)

• Types of Fibrous Joints:

  1. Sutures
     • Composed of a thin layer of dense irregular connective tissue
     • Occur only between skull bones
     • Irregular interlocking edges for added strength
     • In older individuals: Immovable (Synarthrosis)
     • In infants/children: Slightly movable (Amphiarthrosis)
     • Important for skull and brain growth
  2. Syndesmosis
     • Greater distance between articulating surfaces than in sutures
     • Dense irregular connective tissue arranged as a ligament
     • Limits joint movement
     • Example: Distal tibiofibular joint (connects tibia and fibula)
       • Permits slight movement (Amphiarthrosis)
     • Gomphosis
       • Joint between tooth and jawbone
       • Healthy teeth: No movement
  3. Interosseous Membrane
     • Large sheet of dense irregular connective tissue
     • Binds neighboring long bones
     • Permits small amounts of movement
     • Examples:
       • Between radius and ulna in the lower arm
       • Between tibia and fibula in the lower leg