Cartilage

A firm but flexible connective tissue — softer than bone, tougher than soft tissue.

Three types

• Hyaline cartilage — the most common; covers joint surfaces and forms the nose and the rings of the airway.
• Elastic cartilage — springy; forms the external ear and the epiglottis.
• Fibrocartilage — tough and shock-absorbing; forms the discs between vertebrae and the menisci of the knee.

What it does

• Cushions joints and absorbs shock.
• Provides flexible structural support.
• Serves as a template from which most bones form before birth.

Key idea

Cartilage has no blood supply of its own, so it heals slowly and poorly — a major reason joint injuries are so persistent.