Types of Fibrous Joints

Overview of Joint Classifications

• Three structural classifications of joints:
  • Fibrous
  • Cartilaginous
  • Synovial
• Fibrous joints:
  • Made of dense fibrous connective tissue
  • No cavity; bones linked by connective tissue
  • Typically immovable (synarthrotic), but mobility depends on fiber length

Characteristics of Fibrous Joints

• Dense Fibrous Connective Tissue:
  • Vascularized connective tissue proper
  • Densely packed with fibers, providing strength
• Movement:
  • Shorter fibers lead to immovable joints (synarthrotic)
  • Longer fibers offer slight movability

Types of Fibrous Joints

1. Sutures

   • Rigid, interlocking joints of the skull
   • Allow growth during youth
   • Short fibers enable limited expansion and movability
   • As one ages, sutures ossify and fuse (synostosis), becoming completely immovable
   • Example: Junction of sphenoid and temporal or parietal bones

2. Syndesmoses

   • Bones connected by ligaments (dense regular connective tissue)
   • Longer fibers allow for some movability
   • Fiber length varies, influencing degree of movement
   • Example:
     • Tibiofibular joint (limited movement)
     • Interosseous membrane between radius and ulna or tibia and fibula (allows slight movement)
   • Offers limited movement, classified between synarthrosis and amphiarthrosis

3. Gomphoses

   • Peg-in-socket joints
   • Teeth in alveolar sockets
   • Held by periodontal ligament (gomphosal fibers)
   • Teeth are not bone but structurally similar; more akin to nervous system and skin developmentally
   • Immobile, thus synarthrotic

Key Concepts

• Synarthrosis: Immovable joint
• Amphiarthrosis: Slightly movable joint
• Synostosis: Fusion of bones after ossification

These notes summarize the types and characteristics of fibrous joints, detailing their structure, examples, and functionality.