Chapter 6: Bone and Skeletal Tissues – Structure, Function, and Classification

Bone and Skeletal Tissues

This chapter introduces the structure and function of bone and skeletal tissues, focusing on cartilage types, bone classification, and the histological and functional aspects of the skeletal system.

Learning Objectives

• Describe the three types of cartilages and compare their composition and function.

• List and explain the functions of bones.

• Classify bone types and provide examples.

• Identify and describe bone markings.

• Distinguish between compact and spongy bone.

• Describe the substances that make up bone and their roles.

• Identify the cell types found in bone tissue.

• Describe bone structure from a histological perspective.

• Explain the processes of intramembranous and endochondral ossification.

• Differentiate between interstitial and appositional bone growth.

• Define rickets and osteoporosis, including causes, risk factors, and treatments.

Cartilages

Overview of Cartilage

Cartilage is a resilient and smooth elastic tissue, a rubber-like padding that covers and protects the ends of long bones at the joints and is a structural component of the rib cage, ear, nose, bronchial tubes, intervertebral discs, and many other body components.

• Locations: External ear, nose, articular surfaces of joints, costal cartilage, intervertebral discs, pubic symphysis, respiratory tubes, and menisci.

• Functions: Provides support, flexibility, and resilience; reduces friction at joints; absorbs shock.

Types of Cartilages

Classification and Structure

There are three main types of cartilage, each with distinct structural and functional properties.

• Hyaline Cartilage: Most abundant type; provides support with flexibility and resilience. Contains fine collagen fibers and chondrocytes in lacunae. Found in articular cartilage of joints, costal cartilage, nose, trachea, and larynx.

• Elastic Cartilage: Similar to hyaline but contains more elastic fibers, allowing it to tolerate repeated bending. Found in the external ear and epiglottis.

• Fibrocartilage: Contains thick collagen fibers, making it highly compressible and able to resist tension. Found in intervertebral discs, pubic symphysis, and menisci of the knee.

Type	Main Features	Locations
Hyaline	Fine collagen fibers, glassy appearance, chondrocytes in lacunae	Articular surfaces, costal cartilage, nose, trachea, larynx
Elastic	Elastic fibers, flexible, resilient	External ear, epiglottis
Fibrocartilage	Thick collagen fibers, strong, compressible	Intervertebral discs, pubic symphysis, menisci

Key Terms: Chondrocyte (cartilage cell), lacuna (small cavity housing a cell), matrix (extracellular substance).

Example:

• The meniscus in the knee joint is composed of fibrocartilage, providing shock absorption and stability.