Cartilaginous joint

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Cartilaginous joints are joints where the bones are connected entirely by cartilage (hyaline or fibrocartilage). They allow more movement than fibrous joints but less than the highly mobile synovial joints. These joints also form growth regions in immature long bones and the intervertebral discs of the spine.

Two main types:
- Primary cartilaginous joints (synchondroses): bones are connected by hyaline cartilage and usually allow very little movement. They may ossify (turn into bone) with age. A common example is the growth plates between ossification centers in long bones.
- Secondary cartilaginous joints (symphyses): these joints involve fibrocartilage and sometimes hyaline cartilage, usually occurring at the midline. Examples include the pubic symphysis, intervertebral discs, and the manubriosternal joint (where the sternum meets the upper part of the sternum).

At a symphysis, the joint surfaces are covered with hyaline cartilage and separated by a thick pad of fibrocartilage. The gap between the bones can be narrow or wide:
- Narrow gaps: pubic symphysis, manubriosternal joint.
- Wide gaps: intervertebral discs between adjacent vertebrae.

The intervertebral disc is a thick fibrocartilaginous pad that unites adjacent vertebrae, provides cushioning, and allows small movements. This helps with lifting, running, and jumping.