Stress (emotional/mental, physical, and/or chemical) that is perceived to be beyond one's ability to adapt to elicits a defense strategy in the body that starts with a decrease in blood supply to the higher brain centers (frontal lobes of the cortex) and a change in tone of the nervous system.
Information about the stressful event is mechanically stored in the spinal cord as vibratory mechanical tension - Adverse Mechanical Cord Tension (AMCT) - that involves areas of the spine where the protective coverings of the spinal cord connect to the vertebrae.
This adaptive defense strategy is characterized by a cascade of effects, such as a change in perceptions, an elongation of the spinal cord, a more rigid spinal structure with fixations and misalignments (vertebral subluxations); and altered posture reflecting this "armored" or "hyper-vigilant" state (i.e., head goes forward, spine and shoulders round forward, etc.).