A synchondrosis (or primary cartilaginous joint) is a type of cartilaginous joint where hyaline cartilage completely joins together two bones. Synchondroses are different from symphyses (secondary cartilaginous joints), which are formed of fibrocartilage, and from synostosis (ossified junctions), which is the fusion of two or more bones. Synchondroses are immovable joints and are thus referred to as synarthroses.

Examples in the human body

Permanent synchondroses

• first sternocostal joint (where first rib meets the manubrium of the sternum)

• petro-occipital synchondrosis

Temporary synchondroses (fuse during development)

• epiphyseal plates

• apophyses

• synchondroses in the developing hip bone composed of the ilium, ischium and pubis

• spheno-occipital synchondrosis

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