Cartilage

• Cartilage is being presented by Julie Watson
• The GDC learning outcomes include 1.1.5, 1.1.6 and 1.17

Learning Outcomes

• Describe composition and development of cartilage.
• Identify differences types of cartilage and where they are found.
• General function of cartilage types in the body.
• Prior human biology learning is expected.

General Info on Cartilage

• A firm, avascular, non-calcified connective tissue.
• Forms much of the temporary skeleton in the embryo / fetus.
• Frequently serves as a model or template for the bones of the skeleton.
• Present on articular surfaces of free-moving joints allowing for flexibility.
• The most important cartilage in the head and neck is the TMJ.
• Issues with the TMJ may have a significant impact, with patients presenting with limited opening and discomfort.
• Cartilage depends on surrounding connective tissue for cellular nutrition, called the perichondrium and described as a fibrous connective tissue sheath.
• Cartilage is made up of cells and a matrix which includes fibers / collagen/ intracellular substances

Matrix

• Ground substance.
• Highly hydrogenated gel composed of proteoglycan, chondronectin and water.

Fibres

• The type and number of fibers depends on the type of cartilage.
• Fibers can be up to 40% of the dry weight of cartilage, giving it strength.

Perichondrium

• Capsular sheath that surrounds cartilage.

Chrondroblasts and Chondrocytes

• Immature cells, chondroblasts, produce cartilage matrix.
• Mature chondroblasts, chondrocytes, maintain the cartilage matrix.

Types of Cartilage

• Hyaline
• Fibrous
• Elastic
• All cartilage starts as Hyaline but then modifies according to need.

Hyaline Cartilage

• The principle type of cartilage, particularly in the fetus and infants.
• Characterized by small groups of chondrocyte cells
• The matrix is smooth and solid.
• Appears as a smooth bluish white, glassy tissue.
• It is not easily repaired following injury.
• Locations include articulating surfaces of bone, Costal cartilages attaching the ribs to the sternum and cartilages of the larynx, trachea, and bronchi.

Fibrous Cartilage

• Dense, tough, and slightly flexible tissue.
• Characterized by groups of chondrocytes separated from each other by thick bundles of collagen fibers.
• Collagen fibers are arranged predominantly in tight parallel bundles.
• Locations include: intervertebral discs, knee and jaw joints, surrounding the rim of the bony sockets of the hip and shoulder joints, and the pubic symphysis.

Elastic Cartilage

• Elastic fibers feature in the intracellular matrix.
• The least common type of cartilage tissue.
• Location: pinna of the ear, epiglottis and forming part of the tunica media of blood vessel walls.