The complex joint known as the sacroiliac (SI) joint connects the ilium, one of the pelvic bones, to the sacrum, the triangular bone at the base of the spine. Understanding the sacroiliac joint's anatomy is essential to comprehend how it works and the conditions that can affect it. Let's examine its structure and makeup in more detail. Bones: The articulation of the auricular surfaces of the sacrum and ilium results in the formation of the sacroiliac joint. Rough, asymmetrical regions with fibrocartilage cover the auricular surfaces. The synovial portion of the sacrum and the ilium together make up the majority of the joint. Ligaments: The sacroiliac joint is stabilized and supported by several ligaments. These consist of: Anterior sacroiliac ligament: This powerful ligament strengthens the front of the joint by joining the anterior surface of the sacrum to the iliac fossa. Posterior sacroiliac ligament: This ligament supports the back of the joint by joining the ilium to ...