The vagina is a potential space that expands to permit
penile and foal passage. A transverse fold (remnant
of the hymen) overlies the external urethral orifi ce and
is the anatomic division between the vagina, which is anterior, and the vestibule, which is posterior. The
juncture between the vestibule and vagina is referred to
as the vestibulovaginal ring. When closed, this ring
restricts entry of air and debris into the upper tubular
tract. The vulva is limited to the external opening of the
tubular tract.