Amphiarthrooseiksi

Amphiarthrooseiksi are joints with limited mobility, a category between synarthroses, which are immobile, and diarthroses, which are freely movable. These joints provide small, controlled movements that contribute to stability, posture, and the distribution of mechanical stresses in the skeleton. The tissue composition and joint anatomy limit movement while permitting function.

Structurally, amphiarthrooseiksi can be grouped into cartilaginous and fibrous types. Cartilaginous amphiarthrooseiksi include synchondroses, where bones are joined by hyaline cartilage, and symphyses, joined by fibrocartilage. Fibrous amphiarthrooseiksi, or syndesmoses, are joints where bones are bound by ligaments. All these arrangements restrict motion to a small range.

Prominent examples include the pubic symphysis and many vertebral joints, where the intervertebral discs and adjacent cartilage permit slight bending and compression. The distal tibiofibular joint is a fibrous amphiarthrosis that allows a small amount of motion important for load transmission in the ankle.

Functionally, amphiarthroses provide shock absorption and load sharing while maintaining stability. They have varying healing properties compared with diarthrotic joints; injuries such as symphyseal separations or syndesmotic injuries require careful management because motion can be restricted or pain can be produced by inflammation or degenerative changes.