A cartilaginous joint is a joint where cartilage connects the bones. Cartilage is a tough but flexible connective tissue that comes in three types: hyaline (also called articular), elastic and fibrocartilage. Unlike the more common synovial joints, cartilaginous joints do not have a space (joint cavity) between the bones. The two types of cartilaginous joints are synchondroses and symphyses.
In a synchondrosis joint, a bar or plate of hyaline cartilage connects the bones. During childhood, these joints provide a place for bone to grow, but most synchondroses become immovable (synarthrotic) after childhood.
The skull contains a few synchondroses but the most common synchondroses are the epiphyseal plates that connect the diaphysis (shaft) and epiphysis (end of bone) regions in the long bones (such as the femur). Epiphyseal plates are temporary joints that eventually become synostoses (that is, the parts of the bones become completely fused). Another example of a synchondrosis joint is the joint between first rib and the manubrium of the sternum, which also eventually turns into solid bone.
In a symphysis joint, hyaline cartilage covers the articular surfaces of the bones. This cartilage fuses into a pad or plate of fibrocartilage. Because fibrocartilage is compressible and resilient, symphyses are slightly movable (amphiarthrotic). These joints provide strength and flexibility. Examples include the intervertebral joints (between the bones of the spine) and the pubic symphysis of the pelvis.
Other Types of Joints
In addition to cartilaginous joints, the human body has two other classes of joints: synovial and fibrous.
Synovial joints are freely mobile joints where ligaments generally connect the bones. These joints contain synovial fluid in a space (joint cavity) between the bones that helps create a cushion and smooth movement. Most of the joints in the human body are one of the six types of synovial joint: ball and socket, plane, hunge, pivot, condyloid or saddle.
The other type of joint is the fibrous joint, where dense (fibrous) connective tissue connects the bones. The three types of fibrous joints are suture, syndesmosis and gomphosis. Suture and gomphosis joints are completely immobile and syndesmosis joints have very little movement.