Skeletal System Overview

Introduction to Bones and Cartilage

• Bones: Primarily provide support and protection to the body.
• Cartilage: Important component of the skeleton, similar to bones but with specific differences.
  • Watery and resistant to compression.

Components of the Skeleton

• Axial Skeleton: Includes torso and head.
• Appendicular Skeleton: Includes appendages, pectoral girdle, and pelvic girdle.

Types of Cartilage

Hyaline Cartilage

• Most common type of cartilage.
• Provides support and is crucial for bone production initiation.
• Example: Costal cartilages (connect sternum to ribs).

Fibrocartilage

• Strongest type of cartilage.
• Highly resistant to compression.
• Locations:
  • Menisci of the knee.
  • Pubic symphysis.
  • Discs in the vertebral column.

Elastic Cartilage

• Flexible due to elastin fibers.
• Examples:
  • Outer ear.
  • Epiglottis (facilitates air and food passage between lungs and esophagus).

Histological Features of Cartilage

• All types have chondrocytes inside lacunae.
• Primary matrix composed of collagen.
• Fibrocartilage: Collagen fibers and chondrocytes in alternating rows.

Bone Shapes

Long Bones

• Characterized by being longer than they are wide.
• Examples:
  • Humerus.
  • Phalanges.
  • Metacarpals.
  • Metatarsals.

Irregular Bones

• Complex shapes not fitting other categories.
• Examples:
  • Vertebrae.
  • Some facial bones.
  • Parts of the pelvic bone.

Flat Bones

• Thin, flattened, and often curved.
• Examples:
  • Sternum.
  • Ilium of the pelvic bone.
  • Skull bones.
  • Ribs.

Short Bones

• Roughly cube-shaped.
• Examples:
  • Carpal bones (wrist).
  • Tarsal bones (ankle).
  • Patella (kneecap) - a type of sesamoid bone.