There are three types of constipation.

Defecation is difficult as a result of reduced contraction of the intestinum crassum.

It is often the result of reduced tension or inadequate peristalsis of the intestinum crassum. Constipation of such kind is often associated with abdominal distension, loss of appetite, sense of incomplete emptying after a bowel movement. Habitual constipation is more common to women and aging people as a result of dietary habit and environment.

Spasmodic contraction occurs when the intestinum crassum is too nervous, thus making feces difficult to pass through or difficult to defecate. It is rather common for young people and is sometimes accompanied with lower abdominal pain. It is often the result of autonomic instability which makes the intestinum crassum hypersensitive.
Irritating bowel syndrome (IBS) characterized by repeated constipation and diarrhea is getting increasing popular as a result of intestinum crassum hypersensitivity from stress.

In general, the sense of bowel movement comes when feces are pushed outside the anus. However, if we try to hold the bowel, anal nerves will become slow in response, even when feces are in the anus, we do not feel the sense of bowel movement.
When there is a large amount of feces deposited in the anus, feces will turn hard after the water they contain is absorbed. This way, the feces will block the anus like a cover.