Bones and Skeletal Tissues: Structure, Function, and Development

Bones and Skeletal Tissues

Introduction

The study of bones and skeletal tissues is fundamental to understanding the human body's support, movement, and protection mechanisms. Knowledge of bone anatomy and remodeling is essential for diagnosing and treating bone diseases such as osteoporosis.

6.1 Skeletal Cartilages

Overview of Skeletal Cartilage

The human skeleton initially consists entirely of cartilage, which is gradually replaced by bone during development, except in regions where flexibility is required.

• Cartilage is a resilient, molded tissue composed primarily of water.

• It contains no blood vessels or nerves, making it avascular and non-innervated.

Perichondrium

• The perichondrium is a layer of dense connective tissue that surrounds cartilage, acting like a girdle.

• It helps cartilage resist outward expansion and contains blood vessels for nutrient delivery.

Cartilage Cells

• Chondrocytes are the primary cells of cartilage, encased in small cavities called lacunae within a jelly-like extracellular matrix.

Basic Structure, Types, and Location of Cartilage

Types of Cartilage

Type	Main Features	Locations
Hyaline Cartilage	Most abundant; provides support, flexibility, and resilience; contains fine collagen fibers	Articular (joints), costal (ribs), respiratory (larynx), nasal cartilage (nose)
Elastic Cartilage	Similar to hyaline cartilage but contains elastic fibers	External ear, epiglottis
Fibrocartilage	Thick collagen fibers; has great tensile strength	Menisci of knee, intervertebral discs

Key Points

• Hyaline cartilage is the most common type, providing smooth surfaces for joint movement and flexibility in respiratory structures.

• Elastic cartilage offers greater flexibility, found in structures that require shape retention after bending.

• Fibrocartilage is highly durable and resistant to compression, found in areas subject to heavy pressure and stretch.

Example

• The meniscus in the knee is an example of fibrocartilage, providing cushioning and stability.

• The epiglottis is an example of elastic cartilage, allowing it to bend and return to its original shape during swallowing.

Additional info: Cartilage plays a crucial role in early skeletal development and remains in adult joints to facilitate smooth movement and absorb shock.