symfysen

Symfysen (singular: symfys; English: symphyses) are a class of joints in the skeleton classified as secondary cartilaginous joints (amphiarthroses). In these joints, the neighboring bones are joined by a pad of fibrocartilage, and the joint surfaces are typically covered by hyaline cartilage. The resulting structure allows limited movement while providing stability and shock absorption.

A defining feature of symphyses is the fibrocartilaginous interposed disc or pad that unites the bones. This configuration is seen in several key joints, most notably the pubic symphysis between the pubic bones and the intervertebral joints between adjacent vertebral bodies (the intervertebral discs). The mandibular symphysis, where the two halves of the mandible fuse, is another example. Movement at symphyses is small, but it can contribute to flexibility and load distribution in the spine and pelvis.

Common locations and functions include stabilizing the pelvis and spine while permitting limited translational and rotational movement. The pubic symphysis acts as a midline support of the pelvic ring and can widen during childbirth under hormonal influence. Intervertebral symphyses provide cushioning between vertebrae and allow modest spine flexion, extension, and lateral bending.

Clinical relevance varies by site. Pubic symphysis diastasis can occur after trauma or during late pregnancy, causing pelvic pain. Degenerative changes can affect intervertebral discs, contributing to back pain and reduced mobility. Understanding symphyses helps explain certain patterns of spinal and pelvic biomechanics and related pathologies.