Cartilage functions to:

• (1) support the body

• (2) provide a framework

• (3) provide attachment sites for muscles

• (4) protect underlying tissues

• (5) helps provide flexibility

• (6) form structural models for growing bones

As an important aside: the first four listed functions above are all actually functions of bones as well.

A general description of cartilage from a connective tissue viewpoint would be that it consists of cells called chondrocytes contained in small chambers called lacunae. These lacunae are completely surrounded by intercellular matrix. The consistency of the ground substance is “gel-like.” The composition of the fibres varies with the type of cartilage.

Reminder:

No matter what the tissue, one characteristic common to all connective tissue is that it is composed mostly of an intercellular material called “matrix.”

matrix

matrix

matrix

matrixmatrix

Tissue cells are then contained in this intercellular matrix but are "far" apart, relatively speaking.

matrix

matrix

matrix

matrixmatrix

cells

It is actually the composition of this matrix which gives each type of connective tissue its individual characteristics. Matrix itself is actually composed of two different things. These are protein fibres and ground substance.

ground substance

protein fibres

Ground Substance is described as an amorphous (shapeless or formless), extracellular material which serves as a diffusion medium in the spaces around the cells and fibers, and it plays a major role in determining the physical nature of a connective tissue.

ground substance

The fibres consist of long protein molecules that are embedded in the ground substance. They are produced by the tissue cells which are themselves contained within the matrix. There are two types of fibres contained in the connective tissue we will study – collagen fibers made from collagen or “tropocollagen” molecules and elastic fibers made from elastin molecules.

Cartilage Description Once Again:

A general description of cartilage from a connective tissue viewpoint would be that it consists of cells called chondrocytes contained in small chambers called lacunae. These lacunae are completely surrounded by intercellular matrix. The consistency of the ground substance is “gel-like.” The composition of the fibres varies with the type of cartilage.

Chondrocytes

Lacunae

There are three different types of cartilage found in the human body. They are classified according to their fibre type (collagen or elastic) and the fibre density (fine or thick). These three are:

Elastic Cartilage

Fibrous Cartilage or “Fibrocartilage”

Hyaline Cartilage

3 Types of Cartilage Tissue

Hyaline -This is the most common type of cartilage in the body. It has a milky white, yet glassy appearance. This is due to the composition of its matrix. It consists of fine collagenous fibres embedded in a firm gel ground substance. This structure gives hyaline cartilage good strength with some flexibility. It is the “main structural” cartilage of the body and is used to replace bone wherever greater flexibility is needed. It is located throughout the body in places such as the ends of bones at many joints, the “soft" part of the nose, and the rings of the trachea and bronchial tubes. It is also the type of cartilage that makes up a great deal of the thoracic cage and the entire fetal skeleton.

Elastic -This is the least common type of cartilage found in the body. It has a yellowish appearance due to elastic fibres of elastin molecules in the intercellular matrix. Elastic cartilage is not very "strong" by comparison to hyaline cartilage, but it is much more flexible and it also has some elasticity. It is found in areas where its primary property, elasticity – the ability of a substance to return to an initial form after deformation – is of importance. The most obvious places where elastic cartilage can be found is in the external part of the ear and the epiglottis.

Fibrous -This type of cartilage has a duller, white appearance. It consists of thick collagenous fibres contained in a firm gel ground substance. It is very tough and has great tensile strength. The difference between it and hyaline is that fibrous cartilage has a much denser matrix which contains far fewer chondrocytes and thicker collagen fibres. The main function of fibrocartilage is to serve as a shock absorber for structures where excessive pressures are generated. It is therefore located in areas where great stresses are common. The intervertebral discs of the spinal column, the meniscus cartilage of the knee, and the cartilage of the symphysis pubis joint are all fibrous cartilage.

Dense (Regular) Connective Tissue• Fibrous connective tissue

– Tendons

– Ligaments

• Rigid Connective Tissue– Cartilage

• Hyaline• Elastic• Fibrous

Rigid Connective TissueCartilage

HyalineElasticFibrous

BoneCompactSpongy