These are tight places in certain muscles which cause pain elsewhere in the body. For example, tense muscles in shoulder can cause pain in fingers. This mobile application shows where the 70 different muscles in the body are, explaining how they work, along with detailed graphics.
You can view each muscle individually, or use the 'zones' view to see all the muscles of a specific area, the abdomen or the upper thigh, for example, reports the Daily Mail. There are also pointers on how to tackle muscle pain problems.
"Trigger and pressure points have been used in medicine for thousands of years, and the practice of acupuncture is based on this," says Arun Ghosh, general practitioner at the Spire Hospital, Liverpool.
"However, I would be very careful about using an app like this for a diagnosis. Some conditions are not obvious."
"For example, back pain high up the spine might well be caused by a disc injury lower down, rather than a muscle problem.""You always need proper scans and examinations to find where a problem begins," he adds.