instant movement
A sudden painful involuntary contraction of a muscle is called a muscle cramp. This can happen due to various reasons such as dehydration, muscle fatigue, or poor blood circulation. Stretching and massaging the affected muscle can help alleviate the discomfort.
a cramp or spasm.
Often it is called a cramp.
A cramp is a sudden over-shortening of a muscle. Cramps are involuntary and, often, severe. They can be extremely painful.
It is called a Tracheospasm
A painful and involuntary muscular contraction.
A painful muscle contraction is a cramp.
A muscle spasm caused by prolonged muscle contraction is called a "cramp." This localized involuntary contraction can be triggered by muscle fatigue, dehydration, or electrolyte imbalances. Cramps are usually sudden and can be painful, but they typically resolve on their own.
A painful contraction of a muscle is a cramp or charley horse.
It is called 'Cardiac Arrest". http://en.wikipedia.org/wiki/Cardiac_arrest
The suffix for sudden involuntary contraction of muscle is "-spasm." So, the condition you are referring to in the distal region of the stomach would be called "gastros- (stomach) -spasm."
Due to the forming of guided flow streams resembling those of venturi, the irreversibilities from a sudden contraction are less than those from a sudden expansion. That's why head losses due to sudden expansion are more than sudden contraction.