What is Cartilage?
Cartilage is an important structure in human body and is present in many parts of the body. It is not hard but is firm and stiff and slightly flexible. Due to this cartilage helps to bind to other tissues and usually acts as a binding between bone and muscles and provides support to the parts it is attached to.
Characteristics of Cartilage
Cartilage is a type of connective tissue, which is flexible in nature and does not have any blood or nerve supply. It derives its nutrition with diffusion from other cells and tissues. Due to lack of blood supply, if a cartilage gets injured or damaged, the healing can be very slow and is difficult to repair. Cartilage is made of numerous fibers, which differ from each other. Based on these differences, cartilage can be classified into three types and their location and function varies accordingly.
Cartilage is found in joints like knees, elbows, ankles, etc. between the spinal vertebrae, at the end of the ribs, linings of windpipe (trachea) and voice-box (larynx) and the respiratory airways (bronchioles) in the lungs. Cartilage is also present in the tip of the nose, the outmost part of ears, which make these structures little flexible.
What is the Function of Cartilage in a Joint?
Cartilage contains substances like proteins and certain nutrients that serve various functions like:
- Cartilage provides mechanical support to the adjoining structures. Cartilage also helps in easy movements of the joints and protects bones and muscles from damage.
- Cartilage serves as a cushion where the bone and the muscles get attached or in between two bones to avoid friction and damage to the bones.
Types of Cartilage and Its Location and Function
There are primarily three types of cartilage:
Hyaline Cartilage – This cartilage appears glassy, hence the name (hyalos means glassy in Greek) and is located in the tip of the nose, larynx, trachea and the junction where the ribs get attached to the breastbone (sternum). It is made up of thin fibers of collagen and is the weakest of all the three types. Although it is able to support weight bearing joints and is flexible and rubbery but its capacity of healing and regeneration is poor.
Functions of Hyaline Cartilage Include:
- Hyaline cartilage attaches well to the bones that need to be in place and facilitates movement of the joints.
- Hyaline cartilage provides smooth surface for movement at the joints and reduces friction of joints.
- It supports the parts to which it is attached and promotes growth of the long bones.
Fibrocartilage – This type of cartilage has a lot of collagen fibers, is tough, inflexible and is supposed to be the strongest of all three types of cartilage. Fibrocartilage is located at the front of the pelvic bone (pubic symphysis), intervertebral disc, shoulder joint, temporomandibular or the jaw joint and the menisci in the knee joint. The unique location of this cartilage makes it responsible for peculiar functions, which include:
- Fibrocartilage acts as a shock absorber in between joints, vertebrae and other structures, thus preventing damage to the bones when performing routine or high impact activities.
- When fibrocartilage is present in specific type of joints like ball and socket joint, e.g. shoulder joint, it makes provision or deepens sockets for proper movement of the joint, so as to prevent dislocation of the ball from the socket.
- It provides firmness to the joint, while allowing the required degree of movement.
Elastic Cartilage – This type of cartilage provides elasticity, is more flexible and is located in the lobe of outer ear, epiglottis (a part above the larynx) and the larynx.
Functions of elastic cartilage include giving shape and elasticity to the part. In case of parts like epiglottis, which need to be moved when required, elastic cartilage offers free movement to the parts and aids in effective functioning of the part. It also provides support and strength to the structures.
What Happens if Cartilage Wears Away or Gets Damaged?
Certain conditions can affect the cartilage resulting in improper functioning of cartilage or damage to joints or structures.
Injury or trauma to the joint commonly occurring in sportspersons or after accidents, can result in tearing of the cartilage, which can further increase friction of the bones and cause joint pain. Osteoarthritis is a degenerative condition, in which the cartilage thins or wears off due to excessive usage or wear and tear causing pain and difficulty in moving the joint.
Cartilage in ribs can get inflamed in costochondritis and cause rib pain. Cartilage cushion in spinal vertebrae, if damaged due to aging or trauma, can cause protrusion or herniation of spinal disc, causing back pain or nerve compression.
Certain genetic conditions or autoimmune conditions affecting the cartilage or connective tissue can cause easy damage to the cartilage and result in specific complaints.