Continuation Joints of the Pelvis Recall that a joint as the name suggests is a meeting point or an articulation of two bones. The bony pelvis has four major joints as follows: Lumbosacral joint Sacrococcygeal joint Sacroiliac joint Pubic symphysis (or symphysis pubis) Lumbosacral joint It is a cartilaginous joint between the fifth lumbar vertebrae (L5) and the sacrum. This joint allows flexion, extension and minimal lateral rotation Sacrococcygeal joint It is an articulation between the apex of the sacrum and the base of the coccyx. It is slightly mobile allowing limited degree of flexion and extension. It is even more mobile in the female. This mobility increases the anteroposterior diameter of the pelvis during labour and defecation. It is a cartilaginous joint. Sacroiliac joint The sacroiliac joint is a synovial joint formed by the auricular surface of the sacrum and the ilium of the hipbones. There are right and left sacroiliac joints. These joints allow very little to no movement