With cranial extension, the sacral base moves in which direction?

With cranial extension, the sacral base moves in which direction?

• A. Anteriorly
• B. Posteriorly
• C. Superior
• D. Inferior

Answer: (A)

In the Primary Respiratory Mechanism, cranial and sacral motions are linked. When the cranium extends, the spheno-occipital relationship shifts so the sacrum undergoes nutation, meaning the base of the sacrum moves anteriorly. This anterior movement of the sacral base aligns with cranial extension. By contrast, cranial flexion would pair with counternutation, moving the base posteriorly. So the sacral base moves anteriorly with cranial extension.

In the Primary Respiratory Mechanism, cranial and sacral motions are linked. When the cranium extends, the spheno-occipital relationship shifts so the sacrum undergoes nutation, meaning the base of the sacrum moves anteriorly. This anterior movement of the sacral base aligns with cranial extension. By contrast, cranial flexion would pair with counternutation, moving the base posteriorly. So the sacral base moves anteriorly with cranial extension.