Amphiarthrosen

Amphiarthrosen, or amphiarthroses, are joints that permit limited, but not immobile, movement. They occupy an intermediate position on the spectrum of joint mobility, between the immovable synarthroses and the freely movable diarthroses. The mobility of amphiarthroses is limited by connective tissue structures such as ligaments and cartilage, which provide stability while allowing some give under load.

Morphology and categories. Amphiarthroses can be classified by the type of connective tissue that joins the bones. Fibrous amphiarthroses, or syndesmoses, are linked by interosseous ligaments and permit modest motion; examples include the distal tibiofibular joint and the radioulnar interosseous membrane. Cartilaginous amphiarthroses include symphyses, in which bones are joined by fibrocartilage (as in the pubic symphysis and the intervertebral joints between vertebral bodies), and synchondroses, where bones are joined by hyaline cartilage and allow limited movement.

Examples and occurrences. The pubic symphysis is a classic cartilaginous amphiarthrosis that absorbs load and allows slight pelvic movement. Intervertebral joints between adjacent vertebral bodies function as symphyses, contributing to flexibility of the spine while maintaining stability. The distal tibiofibular joint represents a syndesmotic amphiarthrosis that maintains leg stability while permitting small amounts of motion, particularly during weight bearing.

Clinical relevance. Amphiarthroses are generally more susceptible to degenerative or traumatic changes than synarthroses but less prone to motion-related injury than diarthroses. Understanding their limited mobility helps explain how these joints contribute to stability and shock absorption in the axial and appendicular skeleton.