Characteristics of Cartilage

Cartilage Characteristics

• A rubbery type of connective tissue, tough and resilient
• Lacks blood vessels, nerves, and lymphatics
• Receives nutrition through diffusion from the blood vessels of perichondrium
• Composed of mature cartilage cells (chondrocytes), fibers, and matrix
• Resists compression forces and friction
• Has a great capacity for growth through multiplication of chondroblasts (immature cartilage cells)

Types of Cartilage

Hyaline Cartilage

• Most widespread in the human body
• Matrix is translucent
• Cartilage cells are numerous, small, and rounded
• Found in:
  • Developing bones in fetuses
  • Epiphyseal plates of long bones
  • Articular cartilage in joints
  • Costal cartilage and xiphoid process
  • Larynx (except epiglottis)
• Ossification occurs in old age in certain sites (larynx and epiphyseal cartilages)

White Fibrocartilage

• Matrix is opaque due to rich collagen bundles
• Cartilage cells are few in number
• Found in:
  • Intervertebral discs (IVD)
  • Menisci
  • Articular discs
• Ossification does not occur in old age

Yellow Elastic Fibrocartilage

• Matrix appears yellow due to rich yellow elastic fibers
• Cartilage cells are abundant
• Found in:
  • Tip of the nose
  • Auricle of the ear
  • Epiglottis
• Ossification does not occur in old age

Knee Joint

• A major weight-bearing joint
• Stability depends on quadriceps and ligaments
• Articular surfaces are incongruent
• Subject to significant biomechanical stress daily, making it a common site of injury
• Unnatural movements (e.g., twisting, pivoting, sudden change of direction, or forceful blow) can cause injury

Patella Function

• Not mentioned in the text, but patella is not mentioned in the provided text

Fibrous Joints

• Three types: gomphosis, sutural joints, and syndesmosis

Gomphosis

• Cone-shaped root of a tooth fits into an alveolar socket of the maxilla or mandible
• Tooth is attached to the alveolar socket by a periodontal ligament
• Joint is immovable

Sutural Joints

• Found between bones of the skull (e.g., coronal suture: between frontal and parietal bones, sagittal suture: between parietal bones)
• Bones are bounded together by a sutural ligament
• In adults, sutures allow almost no movement between bones
• Sutural joints are present between bones that ossify in membrane
• Classified according to shapes of bone margins into:
  • Plane suture: median palatine suture
  • Serrate sutures: sagittal suture
  • Denticulate suture: lambdoid suture
  • Squamous sutures: parieto-temporal suture
  • Schindylesis: e.g., between the rostrum of the sphenoid and the ala of the vomer

Syndesmosis

• Bones are held together by an interosseous ligament
• Slight movement is possible
• Examples not provided in the text

Cartilaginous Joints

• Two types: primary cartilaginous joints (synchondrosis) and secondary cartilaginous joints (symphysis)

Primary Cartilaginous Joints (Synchondrosis)

• Articulating surfaces are connected via hyaline cartilage
• Joint is immovable
• Temporary in nature (after a certain age, cartilage plate is replaced by bone formation)
• Examples: between epiphysis and diaphysis (epiphyseal plate)

Secondary Cartilaginous Joints (Symphysis)

• Articulating surfaces are connected via fibrocartilage
• Joints are slightly movable
• Permanent joints that persist throughout life
• Found in the median plane
• Examples: elbow and knee joints
• Some joints are complex, with a fibrocartilaginous disc between articulated surfaces, dividing the joint cavity into two compartments

Classification of Joints

• Based on structures or function
• Functional classification:
  • Synarthroses (immovable): common in axial skeleton (fibrous-sutures)
  • Amphiarthroses (slightly movable): common in axial skeleton (secondary cartilaginous joints)
  • Diarthroses (freely movable): common in appendicular skeleton (synovial joints)