trigger zone

1:  trigger point After identifying and manually stabilizing the tender area in the taut band with the fingers, the needle is quickly passed through the skin and then into the trigger zone.—Robert D. Gerwin and Jan Dommerholt, in Pain Management: A Practical Guide for Clinicians, 6th edition, 2002

2:  chemoreceptor trigger zone Emesis experts believe that poisons somehow signal a chemical trigger zone, possibly in a region of the brainstem called the area postrema …—Tom Siegfried, The Dallas Morning News, 7 July 1997

3:  the site on an axon where action potentials are initiated that typically occupies the same region as the axon hillock The signal is passively transmitted along the neuron until it reaches the trigger zone where action potentials are generated …—Frank J. Cerney and Harold W. Burton, Exercise Physiology for Healthcare Professionals, 2001