24 (832)

Theoretically, there may be as many as four ways to achieve double locking, with segments cranial to and caudal to the treated segment locked. However, the requirement that the treated segment “receive" flexions from the adjacent locked segments limits the number of possible combina-tions for locking.

For instance, double locking is extremely difficult in the cervical spine itself, except for the C2-C3 segment, where the mechanical convenience pro-vided by the occiput, atlas, and axis moving as a unit permits cranial locking. Cervical segment treatment is also facilitated by the relatively exposed positions of the segments which makes direct manipulation possible. So the advantage offered by double locking may also be achieved through a single cranial/caudal locking. In this case, the Therapist can lock caudally to the segment treated and achieve segment treatment by holding and moving the cranial vertebrae involved. The opposite procedurę may also be used: locking cranial to the segment, and holding and moving the caudal vertebrae involved. Double locking is possible in the thoracic and lumbar spines.

The possible combinations for double locking are listed in Table 2-2.

Table 2-2. Combinations possible for double locking

Part of Spine	Segment Treated In				Locking Caudal to			Locking Cranial to
					Segment Treated			Segment Treated
	Flexions		Rotation	Flexions		Locked for	Flexions		Locked for
	Ventral/	Lateral		Ventral/	Lateral	rotation to	Ventral/	Lateral	rotation to
	Dorsal			Dorsal		2	Dorsal		2
Cervical C2-C3 only	Ventral	Right	Right	Either	Left	Right	Either	Left	Right
	Ventral	Left	Left	Either	Right	Left	Either	Right	Left
	Dorsal	Right	Right	Either	Left	Right	Either	Left	Right
	Dorsal	Left	Left	Either	Right	Left	Either	Right	Left
Cervical-	Ventral	Right	Right	Dorsal	Right	Right	Ventral	Left	Right
thoracic^1	Ventral	Left	Left	Dorsal	Left	Left	Ventral	Right	Left
	Dorsal	Right	Left	Dorsal	Left	Left	Ventral	Right	Left
	Dorsal	Left	Right	Dorsal	Right	Right	Ventral	Left	Right
Thoracic	Ventral	Right	Right	Ventral	Left	Right	Dorsal	Right	Right
& Lumbar	tt	"	tt	Dorsal	Right	Right	Ventral	Left	Right
	Ventral	Left	Left	Ventral	Right	Left	Dorsal	Left	Left
	tt	"	tt	Dorsal	Left	Left	Ventral	Right	Left
	Dorsal	Right	Left	Dorsal	Left	Left	Ventral	Right	Left
	tt	tt	"	Ventra!	Right	Left	Dorsal	Left	Left
	Dorsal	Left	Right	Dorsal	Right	Right	Ventral	Left	Right
		tt		Yentral	Left	Right	Dorsal	Right	Right

Notę: 1) Usually at the C7-T1 segment; may be in segments caudal to C7-T1, in cases where cervical behavior extends caudally into upper thoracic spine. Therapist must test patient to determine location of cervical-thoracic behavior transition.

indicates locking for rotation when used in illustrations.