Unfortunately, the term sphincter isn't reserved just for one thing. There's another two sphincters around our pupils (one each), another two around our eyes, two sphincters in our esophagus (top and bottom), another one at the end of our stomach, one between ileum and colon, another one leading into the duodenum, the anus, two more in our urethra... Not to mention countless precapillary sphincters. Countless.