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.
External Oblique. The largest and most superficial flat muscle in the abdominal wall. Its fibres run inferomedially. As the fibres approach the mid-line, they form an aponeurosis (a broad flat tendon). In the mid-line, the aponeuroses of all the flat muscles become entwined, forming the linea alba.his is a long, paired muscle, found either side of the midline in the abdominal wall. It is split into two by the linea alba. The lateral border of the two muscles create a surface marking called the linea semilunaris.