Final answer:
The inferior transverse axis of the sacrum is primarily involved in flexion and extension, which are anterior or posterior movements in the sagittal plane.
Step-by-step explanation:
The movement involved with the inferior transverse axis of the sacrum includes flexion and extension. Flexion is the action of bending or decreasing the angle between the bones of the joint, which in the case of the sacrum, refers to the forward bending movement. Extension, on the other hand, is straightening the joint or increasing the angle between the bones, equivalent to a backward bending movement. Both of these actions occur within the sagittal plane. The vertebral column's range of motion varies by region, with different degrees of flexion, extension, lateral flexion, and rotation possible. However, in the context of the sacrum, specifically the movement relative to the inferior transverse axis, the primary motions are flexion and extension.