Sacroiliac joint
Articulatio sacroiliaca
Definition
The sacroiliac joint is an amphiarthrodial joint, formed between the auricular surfaces of the sacrum and the ilium.
The articular surface of each bone is covered with a thin plate of cartilage, thicker on the sacrum than on the ilium. These cartilaginous plates are in close contact with each other, and to a certain extent are united together by irregular patches of softer fibrocartilage, and at their upper and posterior part by fine interosseous fibers. In a considerable part of their extent, especially in advanced life, they are separated by a space containing a synovia-like fluid, and hence the joint presents the characteristics of a diarthrosis.
The ligaments of the sacroiliac joint are:
- Anterior sacroiliac ligament
- Interosseous sacroiliac ligament
- Posterior sacroiliac ligament