Trigger point is a sensitive area in the muscle or connective tissue (fascia) that becomes painful when compressed. Pressing on a trigger point can cause referred pain and can help identify the external area in the body generating the pain. On the other hand, trigger points can also be a point from which pain radiates throughout the muscle and fascia causing myofascial pain syndromes

Reference :spine-health, https://www.spine-health.com/glossary/trigger-point , july 08th,2019