| Joint or ligament | Description | Notes |
|---|---|---|
| iliolumbar ligament | a ligament that connects the transverse process of the L5 vertebra to the iliac crest | the iliolumbar ligament stabilizes the lumbosacral joint |
| lumbosacral joint | the articulation between the L5 vertebral body and the body of the first sacral segment | a symphysis; this articulation is characterized by all of the features of a typical intervertebral articulation which include: an intervertebral disk, anterior and posterior longitudinal ligaments, synovial joints between articular processes, ligamenta flava, interspinal and supraspinal ligaments; a strong iliolumbar ligament strengthens this joint |
| pubic symphysis | the midline joint uniting the superior rami of the two pubic bones | a symphysis; a fibrocartilage interpubic disk unites the bones; the subpubic angle in the female is greater than the subpubic angle in the male |
| sacroiliac joint | the articulation between the ala of the sacrum and the auricular surface of the ilium | a synovial joint; the fibrous articular capsule is thickened dorsally and ventrally to form the sacroiliac ligaments; because of the interlocking nature of the joint surfaces and the strong sacroiliac ligaments, only limited movement is permitted at the sacroiliac joint |
| sacrospinous ligament | the ligament that connects the ischial spine to the lateral surface of the sacrum and coccyx | together with the sacrotuberous ligament, it converts the greater and lesser sciatic notches into greater and lesser sciatic foramina |
| sacrotuberous ligament | the ligament that connects the ischial tuberosity to the lateral surface of the sacrum and coccyx | together with sacrospinous ligament, it converts the greater and lesser sciatic notches into greater and lesser sciatic foramina |