filtrum

Filtrum is a term used in anatomy to refer to a groove or channel, most notably the philtrum—the vertical groove on the midline of the upper lip that runs from the base of the nose to the center of the lip. In some sources, filtrum is used as an alternative or historical name for the philtrum.

In human anatomy, the philtrum (filtrum) is formed by the fusion of the medial nasal prominences with the maxillary prominences during embryonic development. The upper lip’s central groove is flanked by philtral ridges on each side, which give the area its characteristic shape. The philtrum plays a minor cosmetic and sensory role, with no major function attributed beyond aiding facial expression.

Development and variation are common topics related to the filtrum. The depth and visibility of the philtrum vary among individuals and can be affected by age, scarring, or weight changes. Clinically, a smooth or abnormally shallow philtrum can be associated with certain congenital conditions, most notably fetal alcohol spectrum disorders, where diminished philtral definition is a recognizable facial feature. Abnormalities such as cleft lip can involve disruption of the philtral groove.

Outside human anatomy, filtrum may appear in older or non-human anatomical literature to describe similar midline grooves in other species, though the term philtrum remains the standard designation for the corresponding feature in humans. Overall, the filtrum serves as a descriptive term for a midline facial groove with particular emphasis on the upper lip region.