Principles of Manual Medicine
Sacral Nutation
Starting from the neutral position, lumbar extension (backward bending) results in sacral flexion (nutation), while lumbar flexion (foreward bending) results in sacral extension (counternutation).
Anterior nutation (
sacral flexion) is a nodding movement of the sacrum between the innominates, with the sacral base moving anteriorly and inferiorly and the sacral apex moving posteriorly and superiorly. Posterior nutation (
sacral extension) occurs when the sacral base moves posteriorly and superiorly and the sacral apex moves anteriorly and inferiorly (Click here to view an interactive animation of sacral flexion and extension from a
Front view
Top view)
The axis around which this anterior-posterior nutation occurs has been described differently by various investigators but appears to be related to the upper and lower limbs of the sacroiliac joint and their junction somewhere around S2 (
Click here to visualize the axis of sacral flexion/extension from an oblique view).
During anterior nutation, there is an inferior translatory movement of the sacrum. During posterior nutation, there is a superior translatory movement.
Bilateral symmetry of anterior/posterior nutation depends on the symmetry of the two sacroiliac joints. With asymmetry of a patient's two sacroiliac joints being so common, asymmetry of anterior/posterior nutation is also quite common.
Anterior nutation is called sacral flexion in the biomechanical model and sacral extension in the craniosacral model. Posterior nutation is called sacral extension in the biomechanical model and sacral flexion in the craniosacral model.
Join Dr. Philip E. Greenman, D.O., F.A.A.O., as he presents an overview of normal sacral flexion and extension.
Join Dr. Philip E. Greenman, D.O., F.A.A.O., as he presents an overview of pathologic sacral flexion and extension.
View the following video summary of pelvic nutation.
