The Sacroiliac Joint | Sacral Nutation and Counter-nutation

The video tutorial explains the concepts of nutation and counter nutation of the sacrum, focusing on their roles in the stability and mobility of the sacroiliac (SI) joint. Nutation involves the anterior rotation of the sacrum's superior surface and posterior rotation of the inferior surface, while counter nutation is the reverse. The sacrotuberous ligament restricts nutation, and the long dorsal sacroiliac ligament restricts counter nutation. The video emphasizes the SI joint's low mobility, which is crucial for preventing dislocations and ensuring proper load transfer.

What is nutation and how does it affect the position of the sacrum?

Explain the role of the sacrotuberous ligament in restricting nutation.

How does the biceps femoris muscle contribute to the restriction of nutation?

Describe the movement of the sacrum during counter nutation.

What ligaments are involved in restricting counter nutation?

What is the significance of the low mobility of the SI joint?

Discuss the potential consequences of disruption to the sacrotuberous ligament.