You may also have diarrhea or a fever. It is sometimes called stomach flu, but it is not the flu. Germs like viruses and bacteria can cause it. You can catch it from someone else who has it, or you can get it from food poisoning. Food poisoning can happen if you eat foods that contain harmful germs.
The circular muscle located at the entrance and exit to the stomach is called the sphincter. So for this question, you are talking about two distinct sphincters. This anatomical structure is able to open, and contract or close as needed.
The transverse abdominis (TA) muscle is the front wall of the inner core. It is the deepest layer of the abdominal. muscles and the fibers of the muscle run horizontally across the abdomen. When this muscle contracts the. abdomen pulls inward. There needs to be balance between the four layers of the abdominal muscles.