Structure and Functions of Cartilage Tissue
The Structure (Physical Description) of cartilage tissue in general
Cartilage is a connective tissue consisting of a dense matrix of collagen fibres and elastic fibres embedded in a rubbery ground substance. The matrix is produced by cells called chondroblasts, which become embedded in the matrix as chondrocytes.
That is, mature cartilage cells are called chondrocytes.
They occur, either singly or in groups, within spaces called lacunae (sing. lacuna) in the matrix.
The surface of most of the cartilage in the body is surrounded by a membrane of dense irregular connective tissue called perichondrium. This is important to remember especially because, unlike other connective tissues, cartilage contains no blood vessels or nerves except in the perichondrium.
There are three different types (structures) of cartilage that have slightly different structures and functions.
They are hyaline cartilage, fibrocartilage, and elastic cartilage. Each of these is described separately in the sections below.
1.0 Where in the body is hyaline cartilage tissue ?
Hyaline cartilage is the most abundant of the three types of cartilage.
It is found in many locations in the body, including:
- Bronchi, bronchial tubes, costal cartilages, larynx (voice-box), nose, trachea
- Covering the surface of bones at joints - especially in areas where damage due to wear may lead to osteoarthritis incl. e.g. the ends of the long bones, and also the anterior ends of the ribs.
- Embryonic skeleton (i.e. in the fetus).
2.0 The Structure of hyaline cartilage tissue
Hyaline cartilage consists of a bluish-white, shiny ground elastic material with a matrix of chondroitin sulphate into which many fine collagen fibrils are embedded. It contains numerous chondrocytes.
3.0 The Functions of hyaline cartilage tissue
Hyaline cartilage tissue provides smooth surfaces, enabling tissues to move/slide easily over each other, e.g. facilitating smooth movements at joints. It is also provides flexibility and support.
1.0 Where in the body is fibrocartilage tissue ?
- Calli (sing. callus), which is the tissue formed between the ends of the bone at the site of a healing fracture (blood clot -> granulation tissue -> cartilage -> bone);
- Intevertebral discs (i.e. the discs between the vertebrae of the spine);
- Menisci (cartilage pads) of the knee joint.
- Pubic symphysis, which is the position at which the hip bones join at the front of the body.
- Also in the portions of the tendons that insert into the cartilage tissue, especially at joints.
2.0 The Structure of fibrocartilage tissue
Fibrocartilage is a tough form of cartilage that consists of chondrocytes scattered among clearly visible dense bundles of collagen fibres within the matrix. Fibrocartilage lacks a perichondrium.
3.0 The Functions of fibrocartilage tissue
Fibrocartilage tissue provides support and rigidity to attached/surrounding structures and is the strongest of the three types of cartilage.
1.0 Where in the body is elastic cartilage tissue ?
- Auditory (Eustachian) Tubes;
- External Ear (Auricle);
- Epiglottis (the lid on the top of the larynx).
2.0 The Structure of elastic cartilage tissue
In elastic cartilage, which is yellowish in colour, the cartilage cells (chondrocytes) are located in a threadlike network of elastic fibres within the matrix of the cartilage. A perichondrium is present.
3.0 The Functions of elastic cartilage tissue
Elastic cartilages provides support to surrounding structures and helps the define and maintain the shape of the area in which it is present, e.g. the external ear.
See also the related page about the structure and functions of bone tissue.