One meaning of stricture is a nasty criticism, while the other is a sharp contraction of a tube or canal in the body. Either meaning can mean great pain to the person experiencing the stricture.
The noun stricture finds its roots in the Late Latin word strictūra, which came from the stem stringere, "to draw tightly." You might remember that meaning by its relationship with the word constrict, meaning "to tighten or draw in." The additional meaning, that of “a critical remark,” is often used in the plural form — like "the critical strictures against cheating."