Cartilaginous joints are connected entirely by cartilage (fibrocartilage or hyaline). Cartilaginous joints allow more movement between bones than a fibrous joint but less than the highly mobile synovial joint. An example would be the joint between the manubrium and the sternum. Cartilaginous joints also forms the growth regions of immature long bones and the intervertebral discs of the spinal column.
Where the connecting medium is hyaline cartilage, a cartilaginous joint is termed a "synchondrosis," or a "primary cartilaginous joint. " A synchondrosis joint is the first sternocostal joint (where the first rib meets the sternum). In this example, the rib articulates with the sternum via the costal cartilage. (The rest of the sternocostal joints are synovial plane joints. )
Sometimes, this is a temporary form of joint called an "epiphyseal growth plate," where the cartilage is converted into bone before adult life. Such joints are found between the epiphyses and diaphyses of long bones, between the occipital and the sphenoid and for some years after birth, between the petrous portion of the temporal and the jugular process of the occipital bone. The epiphyseal plate is a hyaline cartilage plate in the metaphysis at each end of a long bone. The plate is found in children and adolescents; in adults, who have stopped growing, the plate is replaced by an epiphyseal line. In puberty, increasing levels of estrogen, in both females and males, leads to increased apoptosis of chondrocytes in the epiphyseal plate. Depletion of chondrocytes due to apoptosis leads to less ossification, and growth slows down and later stops when the entire cartilage have become replaced by bone, leaving only a thin epiphyseal scar, which later disappears.