Coupled MotionThe orientation of the facets in the thoracic spine results in both neutral (Type I) and nonneutral (Type II) motion mechanics. The coupling of rotation and sidebending is a complex issue in thoracic regions, depending upon the relative location of the verterbal segments and whether rotation or sidebending is the primary motion.

T1-T3 most commonly exhibit nonneutral (Type II) motion mechanics as a carryover from the lower cervical spine (Click here to visualize coupled right sidebending during normal right rotation of thoracic vertebrae T1-T4 from a -- side view -- front view -- top view).

In general, when the thoracic spine is in the neutral position, sidebending and rotation are coupled to opposite sides (Type I) when sidebending is introduced first (Click here to visualize coupled right rotation during normal left sidebending of thoracic vertebrae T4-T8 from a -- side view -- front view -- top view).

Sidebending and rotation are coupled to the same side (Type II) when rotation is introduced first (Click here to visualize coupled right sidebending during normal right rotation of thoracic vertebrae T4-T8 from a -- side view -- front view -- top view).

Join Dr. Philip E. Greenman, D.O., F.A.A.O., as he discusses Type I and Type II motion mechanics of thoracic vertebrae.

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