PTSD (Post-Traumatic Stress Disorder) hinges on the interrelation of mind and body. However, exclusive emphasis on chemistry or psychology misses the point.
The point is the relationship between memory, sensation, and action (or movement).
Every traumatic event triggers some sort of impulse to action (or movement). If the event is intense enough or repetitive enough, that impulse to action becomes ingrained and habituated (memorized) as a chronic tension pattern, i.e., muscular involvement.
Every muscular tension pattern or action has a corresponding sensation. The habituated sensations of patterns formed during a traumatic event are the sensations of the event, itself, the sensations of the tension pattern formed in that event. However, the vary nature of habituation is its unconscious automaticity, so those sensations remain semi-conscious or unconscious impulses that get triggered and activated by similar, even remotely similar, events.
Bodywork, by contacting habituated muscular tension patterns, awakens corresponding habituated (and so, faded or semi-conscious) sensations. That's why bodywork triggers memories. However, it may or may not be sufficient to release the grip of those memories.
Somatic education, by awakening internal awareness of ones habituated states and by awakening from them into new patterns, supports a person's recovery from and growth past habituated trauma patterns. This principle and process is the basis of Peter Levine's work (although his work intervenes at the autonomic level and not the voluntary level).
In my view, both psychological and sensory-motor approaches to memory are needed.
somatic exercise for Startle Reflex