All of the following are components of vaginal sphincter, EXCEPT:
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.
External urethral sphincter
Internal urethral sphincter
Bulbospongiosus
Pubovaginalis