The vertical groove found on the median line of the upper lip, extending to the nose.
Comment:
Philtrum is modelled as the groove rather than the surface structure itself.; [taxon-note] "vestigial in humans. In humans, the philtrum is formed where the nasomedial and maxillary processes meet during embryonic development (colloquially known as Hulse lines). When these processes fail to fuse fully in humans, a cleft lip (sometimes called a 'hare lip') can result. A flattened or smooth philtrum can be a symptom of fetal alcohol syndrome or Prader-Willi syndrome"
Synonyms:
exact_synonym:
lip philtrum
related_synonym:
infranasal depression; medial cleft; philtral region of upper lip