Final answer:
The two parts of the sacro-iliac ligament are the anterior sacroiliac ligament and the posterior sacroiliac ligament. They support the anterior and posterior aspects of the sacroiliac joint respectively.
Step-by-step explanation:
The two parts of the sacro-iliac ligament are the anterior sacroiliac ligament and the posterior sacroiliac ligament. These ligaments are crucial for the support of the sacroiliac joint, which connects the sacrum to the ilium part of the hip bone. The anterior sacroiliac ligament supports the anterior side of the joint, while the posterior sacroiliac ligament supports the posterior side. Additionally, the sacrospinous ligament and sacrotuberous ligament also play significant roles in pelvic stability by spanning between the sacrum and parts of the hip bone, but they are not considered parts of the sacro-iliac ligament itself.