Head & Neck Anatomy: Cartilage

• Cartilage is a firm, avascular (lacks blood vessels), and non-calcified connective tissue.
• It serves as a temporary skeleton during fetal development, forming a template for future bone growth.
• Cartilage is present on articular surfaces of free-moving joints, providing flexibility and cushioning.

Importance of Cartilage in the Head & Neck

• The most important cartilage is located in the head and neck.
• Issues with the temporomandibular joint (TMJ) can lead to discomfort and limit jaw opening, affecting oral health.

Structure of Cartilage

• Matrix consists of fibers (mainly collagen) and intercellular substances like proteoglycans, which give cartilage its flexibility and resilience.
• Ground substance is a highly hydrated gel composed of proteoglycans and water.
• Collagen fibers provide strength and account for 40% of cartilage's dry weight.
• Chondroblasts are immature cells responsible for producing the cartilage matrix.
• Chondrocytes are mature chondroblasts that maintain the matrix.
• Perichondrium is a fibrous connective tissue sheath surrounding the cartilage, providing nutrients.

Types of Cartilage

• There are three types of cartilage: hyaline, fibrocartilage, and elastic cartilage.

Hyaline Cartilage

• It is the most common type of cartilage, appearing smooth, bluish-white, and glossy.
• Its composition includes a small group of chondrocytes in a solid matrix.
• It functions as a temporary skeleton in the fetus and provides a smooth surface at joint articulations.
• It is located on articulating surfaces of bone, costal cartilages (attaches ribs to the sternum), in the larynx, trachea, and bronchi.
• It is not easily repaired after injury.

Fibrous Cartilage (Fibrocartilage)

• It is dense, tough, and slightly flexible, characterized by thick bundles of collagen fibers.
• Its composition includes groups of chondrocytes separated by dense collagen bundles.
• It provides strength and flexibility, often in areas under high stress.
• It is located in intervertebral discs, the knee, TMJ, pubic symphysis, and around the hip and shoulder joints.

Elastic Cartilage

• It contains elastic fibers in addition to collagen, making it more flexible than other types of cartilage.
• It provides elasticity while maintaining shape.
• It is located in the pinna of the ear, epiglottis, and parts of the tunica media of blood vessel walls.

Functions of Cartilage

• Cartilage provides structural support by forming a flexible and strong framework in the body, particularly during embryonic development.
• It provides joint cushioning by covering joint surfaces, allowing smoother movement and reducing friction between bones.
• Fibrocartilage, in particular, provides shock absorption in joints such as intervertebral discs and knees.
• Elastic cartilage allows structures like the ear and epiglottis to maintain shape while being flexible.