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Overview of Skeletal Cartilages

Apr 9, 2025

Skeletal Cartilages

Introduction

  • Cartilage is a type of skeletal tissue.
  • Most of the skeleton initially starts as cartilage, especially in embryos and fetuses.
  • Cartilage remains in areas requiring flexibility, e.g., rib cage.

Characteristics of Skeletal Cartilage

  • Made of resistant, molded cartilage tissue, primarily water.
  • Lack of blood vessels and nerves, hence no bleeding or pain.
  • Nutrient supply via surrounding perichondrium.
    • Perichondrium: Dense connective tissue that surrounds cartilage, resists outward expansion, and contains blood vessels for nutrient delivery.

Composition

  • Made of chondrocytes: mature cartilage cells in small cavities (lacunae).
  • Chondrocytes maintain the jelly-like extracellular matrix of cartilage.

Types of Cartilage

  1. Hyaline Cartilage

    • Provides support, flexibility, and resilience.
    • Most abundant, contains collagen fibers.
    • Locations: joints (ends of bones), ribs, larger airways (larynx, trachea), nasal cartilage.
  2. Elastic Cartilage

    • Similar to hyaline but with more elastic fibers.
    • Locations: external ear, epiglottis.
    • Function: Allows flexibility and recoiling to original shape.
  3. Fibrocartilage

    • Toughest type due to thick collagen fibers.
    • High tensile strength, resists compression.
    • Locations: menisci of knee, intervertebral discs, pubic symphysis.
    • Function: Provides structural support, allows for slight movement and flexibility.

Growth of Cartilage

  • Appositional Growth

    • Occurs in perichondrium, new matrix laid down at cartilage surface.
    • Analogous to the layering of pearls.
  • Interstitial Growth

    • New cartilage forms from within.
    • Similar to tree growth, new material found deeper within.

Calcification of Cartilage

  • Occurs during normal bone growth and aging.
  • Can calcify due to injury or trauma, leading to hardened cartilage.
  • Calcified cartilage is not true bone due to its avascular nature.