Human Anatomy: Joints and Joint Types

Joints

• Joints are the junctions between bones, which can be immovable, slightly movable, or freely movable.
• Joint terminology:
  • Arthro- and Articular- refer to joints.
  • Arthrology is the study of joints.
  • Articular surfaces are smooth, bony surfaces that come together to form freely movable joints.

Types of Joints

• Fibrous Joints:
  • Immoveable joints with no joint cavity.
  • Held together by fibrous connective tissue (ligaments, tendons).
  • Examples: skull bones (sutures), mandible bone to tooth (gomphosis joint).
• Cartilaginous Joints:
  • Joints held together with cartilage.
  • Allow more movement between bones than fibrous joints but less than synovial joints.
  • Examples: vertebral discs, pubic symphysis, mandibular symphysis.
• Synovial Joints:
  • Freely movable joints.
  • Articular cartilage covers the ends of bones.
  • Have a fibrous joint capsule containing synovial fluid.
  • Ligaments reinforce and stabilize the joint.
  • Examples: hinge, gliding, pivot, and ball and socket joints.

Cartilage

• Found in: larynx, trachea, bronchi, flexible portions of nose, external ear, and connects ribs to sternum.
• Functions:
  • Provides tough yet flexible support.
  • Reduces friction and acts as a cushion between joints.
  • Helps support weight during movement.
  • Important in embryonic development (most bones are first formed as cartilage and later replaced as bone).
• When damaged, cartilage has limited healing ability due to lack of direct blood supply, leading to issues like osteoarthritis.

Synovial Fluid

• Found in synovial joints.
• Helps to minimize friction in the joint and allow for free movement.
• Has a thick, viscous consistency similar to oil.
• Can be sampled through a "joint tap" for examination and analysis.