sacral base

sacral base,

n the uppermost posterior part of the first sacral segment, which articulates with the fifth lumbar vertebral segment.
References in periodicals archive ?
Although there is some controversy regarding what constitutes ideal posture of the pelvis in the sagittal plane, it is generally considered to be a position of anterior tilt such that the sacral base angle measures approximately 30 degrees.
As anterior pelvic tilt and therefore the sacral base angle increases, the lumbar spine must compensate by commensurately increasing its lordosis; similarly, if the sacral base angle decreases, the lumbar spine compensates by decreasing its lordosis (Figure 3).
Righting the tilt posture of the pelvis to a healthy sacral base angle will then allow for the return of a healthy lumbar lordotic curve.