... which includes the anterior two-thirds of the organ, is mobile, and the epithelium on its dorsal aspect is modified so as to form several varieties of papillae. A slight median depression is recognisable on the dorsum as far back as the vallate (circumvallate) papillae, which mark the boundary between the oral and pharyngeal parts. A double fold of mucous membrane—the frenum—connects the under aspect of the tip with the floor of the mouth and the mandible. On each side of the frenum, under the mucous membrane of the tip, are mucous glands—apical ... — Manual of Surgery Volume Second: Extremities—Head—Neck. Sixth Edition. • Alexander Miles