 Like the eyelid, the foreskin is free to move after it separates from the glans, which usually occurs before or during puberty.The foreskin is attached to the glans by a frenulum, a highly vascularized tissue of the penis.The World Health Organization states that "[t]he frenulum forms the interface between the outer and inner foreskin layers, and when the penis is not erect, it tightens to narrow the foreskin opening.