The cartilaginous joints are a group of joints in the skeleton of humans and other vertebrate animals that are made up mainly of a flexible connective tissue called cartilage.
Joints are the junction sites between the bones of the skeleton of vertebrate animals, that is, they are the places in the skeleton where adjacent bones are found that, thanks to the presence of other more flexible tissues, form a connection that usually allows movement from one to the other.
There are different types of joints and their classification can be structural or functional:
Most fibrous joints are immobile joints, that is, they are synarthrosis; all synovial joints are diarthrosis (free movement) and, for the most part, cartilaginous joints are amphiarthrosis, i.e. that have little movement.
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Cartilaginous joints are made up of fibrocartilage or hyaline cartilage-type connective tissue. These joints allow more movement than fibrous joints, but less than synovial joints..
Fibrocartilaginous joints are usually very resistant to bending or pulling, as they are made up of bundles of thick collagen fibers. Hyaline cartilage joints, on the other hand, are less
Cartilaginous joints are very common between the epiphyses and diaphyses of long growing bones. The epiphyses are the widest areas of the bones, that is, the proximal and distal ends. The diaphysis, on the other hand, corresponds to the thinnest part, located between the epiphyses.
During the growth and development of long bones, these regions are joined together by hyaline cartilage, as if they were three separate bones that articulate with each other before fusing into one piece. This allows the bones to grow in length and therefore they are temporary joints..
The site where these joints are located is known as the epiphyseal plate or growth plate and they are described as immobile joints or synchondrosis.
The rib cage has some permanent cartilaginous joints. A good example corresponds to the joints that allow fusion between the pieces of the sternum (sternebrae), as well as the sternocostal joint that facilitates the union between the first rib and the manubrium (one of the pieces of the sternum) thanks to the presence of rib cartilage.
The sacral vertebrae, that is, those found in the sacral region of the spine forming the sacral bone, are attached to each other through transitory hyaline cartilage
The other vertebrae of the spine, on the other hand, are joined together thanks to the presence of what is known as joint discs, which are formed by fibrocartilage.
The pubic portions of the left and right hips are joined together thanks to the presence of a fibrocartilaginous joint known as pubic symphysis, which provides an extremely tight and strong bond between both bones.
Depending on where they are located, the cartilaginous joints fulfill different functions in the body. Among the most important are:
In the skeleton of vertebrates there are two types of cartilaginous joints: the synchondrosis and the symphysis. These joints can be primary (temporary) cartilaginous joints or secondary (permanent) cartilaginous joints, according to its duration in the body.
Synchondroses are cartilaginous joints in which the connecting bones do so through hyaline cartilage. They can be temporary or permanent.
The most common synchondroses are those found in the epiphyseal plate of long growing bones, a type of temporary joint that allows the lengthening of bones during growth, that is, before their ossification (replacement by bone).
The ilium, ischium and pubis of the hip bone are also temporarily attached by hyaline cartilage during the growth of children and adolescents. When the growth of these bones stops, the cartilage is replaced by bone, allowing the fusion of the three bone segments.
The same is true for the sacral vertebrae, which represent the last vertebrae in the spine. Initially these vertebrae are separated by hyaline cartilage that is eventually replaced by bone and that allows the fusion of these to form the sacral bone.
A permanent synchondrosis is one that is present between the first rib and the manubrium (in the sternum), where both bones are articulated by the costal cartilage.
Symphyses are cartilaginous joints in which the bones articulate through fibrocartilaginous tissue, making them particularly resistant to different forces and pressures..
Symphyses are generally classified as amphiarthrosis, as they allow a certain amount of movement between the bones that they bring into contact..
Of this type, the most important joints are those that form the intervertebral discs of the spine, as these are responsible for allowing a small amount of movement between the vertebrae, in addition to cushioning the weight of one on the other, which is essential for various bodily activities.
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