By William M. Maykel, DC, DIBAK
Presented at the International College of Applied Kinesiology-USA
Proceedings of the Annual Meeting, Winter, 1984, p. 79

The sacrum has multiple stress receptors having profound effects on the surrounding musculature. The most important of these is a pair of vertical receptors posterior sacral IBF’s (see picture). They are present in a very high percentage of category I and II’s, and are responsible for balance of the piriformis and gluteus maximus muscles. Correction of these receptors supercedes correction of the related cranial stress receptors. In my experience, the correction of the stress vectors on the sacrum saves a lot of unnecessary origin-insertion, golgi tendon, and muscle spindle correction.

Example of the usual pattern in a category
II-right pi, left as, ilia:

Positive challenge
Weak
piriformis
sacrum art Weak
gluteus maximus
LEFT RIGHT
Strong
gluteus maximus
Strong
piriformis
Correction is opposite the direction of challenge.