Cartilage is a type of connective tissue in the body. It is made of cells called chondrocytes embedded in a matrix, strengthened with fibers of collagen and sometimes elastin, depending on the type. There are three different types: hyaline cartilage, elastic cartilage, and fibrocartilage. This tissue serves to provide structure and support to the body's other tissues without being as hard or rigid as bone. It can also provide a cushioning effect in joints.
This type of tissue is avascular, meaning that it is not supplied by blood vessels; instead, nutrients diffuse through the matrix. Cartilage is usually flexible, again depending on the type. Some of the bodily structures that include it are the ears, nose, ribcage, and intervertebral discs.
Hyaline cartilage makes up the majority of that found in the human body. It lines the bones in joints, helping them to articulate smoothly. This type contains mostly type II collagen fibers.
Elastic cartilage is more flexible than the other types because of the elastin fibers it contains. It is found in the outer ear, the larynx, and the Eustachian tubes, for example. This type provides the perfect balance of structure and flexibility and helps keep tubular structures open.
Fibrocartilage is the strongest and most rigid type of cartilage. It contains more collagen than hyaline, including more type I collagen, which is tougher than type II. Fibrocartilage makes up the intervertebral discs, connects tendons and ligaments to bones, and appears in other high-stress areas. Damaged hyaline cartilage is often replaced with fibrocartilage, which unfortunately does not bear weight as well due to its rigidity.
There are a few disorders associated with cartilage. Chondrodystrophies are a group of disorders in which it is ossified, or transformed into bone. Arthritis is characterized by the degradation of cartilage in the joints, leading to limited movement and pain. Achondroplasia is a disorder resulting in dwarfism. Benign tumors called chondroma can also arise in this tissue.