What structure helps prevent the sacrum from moving anteriorly during weight bearing?

The interosseous sacroiliac ligament plays a crucial role in stabilizing the sacroiliac joint during weight-bearing activities. It is a strong ligament located between the ilium and sacrum, directly supporting the joint by filling the space between the bones. This ligament effectively limits the anterior movement of the sacrum relative to the ilium, which is essential for maintaining pelvic stability and proper biomechanics during various activities such as walking, lifting, or standing.

In contrast, while the anterior longitudinal ligament and posterior longitudinal ligament are important for spinal stability by connecting vertebrae and reinforcing the vertebral column, they do not directly influence the position of the sacrum in the same way. The supraspinous ligament, which runs along the tips of the spinous processes of the vertebrae, also does not directly prevent the anterior movement of the sacrum. Therefore, the interosseous sacroiliac ligament stands out as the key structure in this context, emphasizing its importance in the mechanics of the pelvic region.