<prompt> All of the following are components of vaginal sphincter, EXCEPT:External urethral sphincterInternal urethral sphincterBulbospongiosusPubovaginalis  <response>: Four muscles compress the vagina and act as sphincters:PubovaginalisExternal urethral sphincterUrethrovaginal sphincterBulbospongiosusRef: Clinically Oriented Anatomy By Keith L. Moore, Ahur F. Dalley, II, Anne M. R. Agur, 2013, Page 389. 