Synarthroosi

Synarthroosi, or synarthrosis in English, is a type of joint characterized by immobility or extremely limited movement. It is one of the three functional classifications of joints, the others being amphiarthrosis (slightly movable) and diarthrosis (freely movable). In a synarthrosis, the articulating bones are tightly joined by connective tissue, either fibrous or cartilaginous, which restricts motion and provides stability.

Fibrous synarthroses are connected by dense fibrous connective tissue. They include sutures, such as those between skull bones, and gomphoses, which anchor teeth in their sockets. Sutures typically ossify with age, strengthening the skull, while gomphoses permit little to no movement once the teeth are in place.

Cartilaginous synarthroses involve hyaline cartilage linking the bones. The classic example is synchondrosis, such as the temporary joints at growing points in the immature skeleton. These joints are usually immobile in adults, though they may be temporary and ossify over time to form a synostosis.

Functionally, synarthroses provide stability and protect underlying structures in areas where bones meet and require rigidity. They contrast with amphiarthroses and diarthroses, which permit progressively greater ranges of motion. Developmentally, many synarthroses are replaced by bone through ossification as part of normal growth and maturation.