sínfises

Sínfises, or symphyses in English, are a type of cartilaginous joint in which two bones are joined by a pad or disc of fibrocartilage. They are classified as secondary cartilaginous joints and typically allow only limited movement (amphiarthrosis). The connecting fibrocartilage provides both strength and the ability to absorb mechanical stress, while the joint remains less mobile than a synovial joint. There is usually no synovial cavity in a symphysis.

Common examples include the pubic symphysis, where the pubic bones are united by a fibrocartilaginous disc and reinforced by ligaments such as the superior and inferior pubic ligaments; and the intervertebral joints between adjacent vertebral bodies, which are linked by fibrocartilaginous intervertebral discs composed of the nucleus pulposus and the annulus fibrosus. Some anatomical references also describe the manubriosternal joint, at least in earlier life, as a symphysis.

Structure and variation: A symphysis is characterized by a fibrocartilaginous interposed tissue that provides a smooth articulation surface and distributes load. Movement is constrained by surrounding ligaments and, in the case of intervertebral joints, by the discs and vertebral endplates. Over time, symphyses may ossify or fuse in some individuals.

Clinical relevance: Symphyseal joints can be involved in injuries or degenerative conditions. The pubic symphysis, in particular, may experience diastasis or pain following pelvic trauma, pregnancy, or childbirth, when hormonal changes increase ligamentous laxity to allow pelvic expansion.