Cartilage Types

Types of Cartilage

• Hyaline cartilage is the embryonic form of cartilage, found in the ribs, joints, nose, larynx, and trachea.
• Fibrocartilage is a very strong and pliable connective tissue, found where tendons and ligaments meet bone, and in the menisci, sternoclavicular joint, and annulus fibrosus.
• Elastic cartilage is primarily found in the external ear, Eustachian tube, and epiglottis, and offers flexibility and resilience due to a mixture of elastic fibers.

Growth Pattern of Cartilage

• Cartilage grows in two ways: interstitial growth, where chondrocytes proliferate and divide, producing more matrix inside existing cartilage, and appositional growth, where fresh layers of matrix are added to existing matrix surface by chondroblasts in the perichondrium.

Perichondrium

• The perichondrium is a dense layer of connective tissue that surrounds most cartilage sites.
• Its outer layer contains collagen-producing fibroblasts, while the inner layer houses large numbers of differentiated fibroblasts called chondroblasts.

Chondroblasts

• Chondroblasts produce the elements of the extracellular matrix (ECM).
• Chondroblasts can be seen in the larger ears and noses of older individuals.

Contents of the Extracellular Matrix

• The ECM of cartilage contains three characteristic elements: collagen, proteoglycans, and non-collagenous proteins.

Functions of Cartilage

• Cartilage is a supple tissue that allows for facial movement and provides a lightweight supportive structure in the external ear and the tip and septum of the nose.
• Cartilage acts as a shock absorber, cushioning areas where bone meets bone and preventing abrasion and damage.
• A joint would not be able to bend without the flexibility of cartilage.
• Cartilage also plays a role in bone repair, where it provides a template for ossification.

Bone

• Bone is a modified form of connective tissue that is made of extracellular matrix, cells, and fibers.
• The high concentration of calcium and phosphate-based minerals throughout the connective tissue is responsible for its hard, calcified nature.

Embryology

• The neurocranium and viscerocranium originate from derivatives of the neural crest cells and paraxial mesoderm.
• The paraxial mesoderm also contributes to the formation of the axial skeleton, while the appendicular skeleton originates from the lateral plate mesoderm.

Introduction

• Cartilage is a semi-rigid but flexible avascular connective tissue found at various sites within the body.
• Cartilage function is more than structural and has different functions in the life cycle.
• In the embryo, cartilage provides support and is a precursor to bone.
• Embryonic cartilage either remains as cartilage or provides a substructure for endochondral ossification, meaning it also functions as a template for the rapid growth and development of the musculoskeletal system.

Learn about the different types of cartilage, including hyaline cartilage and fibrous cartilage, and their characteristics in the human body.