23 (885)

3. Only one inflection per locking: The spine is not rubbery; it has an inescapable rigidity (other-wise it could not fulfill its support function). So two changes of flexion from a treated to an adjacent locked segment are not possible. One cannot, for instance, induce both a change from dorsal to ventral flexion and a change from left to right lateral flexion for a single locking. This is equivalent to reąuiring that at least one of the flexions of the treated segment be the same as that of the adjacent locked segment. The relationship is shown schemati-cally in Fig. 11. The single exception is the case of double locking for treatment of the C2-C3 segment, where the occiput, atlas and axis must be moved as a unit.

The simplest inflections to constrain adjacent segment movement involve changes of flexion in the sagittal piane alone, and are used in treat-ments for pure ventral or pure dorsal flexion.

In generał, inflection in the frontal piane (lateral flexion) is adeąuate for locking caudal to or cranial to the segment treated in non-specific treatments. However, for specific treatments, locking both caudal to and cranial to the treated segment, as shown in Figures 8 and 9, is frequently used.

Fig. 11. Diagram of inflections and “transmitted” flexions that “go into” segment treated, with locking both cranial to and caudal to the segment treated. Case shown is that of Fig. 9B.

	SAGITTAL	FRONTAL	ROTATION
	PLANE	PLANE
LOCKING CRANIAL	Ventral	Left	Left
TO TREATED SEGMENT	Flexion	Lateral Flexion	Rotation
	\/	1
	inflection	transmission
	/\	nP
TREATED	Dorsal	Left	Right
SEGMENT	Flexion	Lateral Flexion	Rotation
		\/
	transmission	inflection
	1	/\
LOCKING CAUDAL	Dorsal	Right	Left
TO TREATED SEGMENT	Flexion	Lateral Flexion	Rotation