Lecture Notes: Cartilaginous Joints

Overview

• Three Structural Classifications of Joints:
  • Fibrous
  • Cartilaginous
  • Synovial

Cartilaginous Joints

• Characteristics:
  • Bones united by cartilage (not fibrous tissue)
  • No joint cavity
  • Not highly movable
  • Types of movability: Amphiarthrotic and synarthrotic (not diarthrotic)

Types of Cartilaginous Joints:

Synchondrosis

• Definition:
  • Joints united by hyaline cartilage
  • Almost all are synarthrotic
• Characteristics:
  • Bar or plate of hyaline cartilage connecting bones
  • Hyaline cartilage is slightly movable and stretchable
• Examples:
  • Epiphyseal plates (growth plates):
    • Located between epiphysis and diaphysis of long bones
    • Separated by hyaline cartilage, thus a synchondrosis
  • Costal cartilages of ribs:
    • Ribs meet sternum with hyaline cartilage
    • Allows stretchability of thoracic cage during breathing

Symphysis

• Definition:
  • Joints united by fibrocartilage
  • Strong due to collagen fibers
  • Amphiarthrotic and slightly movable
• Examples:
  • Pubic symphysis:
    • Unites two halves of the pelvis
    • Composed of fibrocartilage
    • Allows flexibility and cushioning during walking
    • Relaxes during labor (hormone relaxin) to widen pelvic outlet
  • Intervertebral joints:
    • Separated by fibrocartilage in the lumbar spine
    • Allows spine flexibility and movability
    • Contains articular cartilage at bone ends but fibrocartilage in the joint center

Important Points

• Synchondrosis and Symphysis differ in cartilage type:

  • Synchondrosis: Hyaline cartilage
  • Symphysis: Fibrocartilage

• Functionality:

  • Synchondrosis generally offers less movement due to its structure of hyaline cartilage.
  • Symphysis allows more movement, such as in the spine and pelvis.