The internal orifice of the uterus (or internal orifice of the cervix uteri or internal os) is an interior narrowing of the uterine cavity. It corresponds to a slight constriction known as the isthmus that can be observed on the surface of the uterus about midway between the apex and base.
Famous quotes containing the word internal:
“No real “vital” character in fiction is altogether a conscious construction of the author. On the contrary, it may be a sort of parasitic growth upon the author’s personality, developing by internal necessity as much as by external addition.”
—T.S. (Thomas Stearns)