Phallus frenulum or prepuce frenulum is a fold of mucous membrane connecting the frenulum with the glans. Some believe that its fundamental function is to close the external outlet of the uriniferous tubule during penetration.
A vascular-nervous bundle runs in the frenulum.
Some patients have a congenital defect involving a too short frenulum, which causes discomfort/pain during erection, penetration and, in extreme cases, the frenulum may be sprained or torn. This is manifested with strong bleeding.
A short penis frenulum is treated by performing phallus frenuloplasty.