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For the publishing house, see Philtrum Press.
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Philtrum visible at centre.
Dog philtrum.png
Dog philtrum
Precursor medial nasal prominence[1]
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Anatomical terminology

The philtrum (Latin: philtrum, Greek: φίλτρον philtron), or medial cleft, is a vertical groove in the middle area of the upper lip, common to many mammals, extending from the nose to the upper lip. Together with a glandular rhinarium and slit-like nostrils, it is believed to constitute the primitive condition for mammals in general.[2]


The philtrum in most mammals is a narrow groove, and may carry moisture from the mouth to the rhinarium or nose pad to keep it wet through capillary action. A wet nose pad is able to trap odor particles better than a dry one, thus it greatly enhances the olfactory system. For humans and most primates, the philtrum survives only as a vestigial medial depression between the nose and upper lip.[3]

The human philtrum, bordered by ridges, is also known as the infranasal depression, but has no apparent function. That may be because most higher primates rely more on vision than on smell and so no longer need a wet nose pad or a philtrum to keep the nose pad wet.[citation needed] Strepsirrhine primates, such as lemurs, still retain the philtrum and the rhinarium, unlike monkeys and apes.[4]



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.[5]


A study of boys with diagnosed autism spectrum disorders found that a broader than average philtrum is one of a cluster of physical abnormalities associated with autism.[6]

Society and culture[edit]

In Jewish mythology, Lailah, the Angel of Conception, lightly taps the infant's upper lip before birth, whereupon the infant forgets the Torah she has taught it.[7] Some people speculate that this is the cause of the philtrum, but it does not have a basis in traditional Jewish texts.[8]

In the film Key Largo (1947), Humphrey Bogart recounts a version of this legend to Lauren Bacall and Lionel Barrymore, as told to him by a fellow soldier. Another version is in the film Mr. Nobody (2009), with the angels of oblivion. And also in the film The Prophecy with christopher walken as gabriel.

See also[edit]

This article uses anatomical terminology; for an overview, see anatomical terminology.


  1. ^ hednk-032 — Embryo Images at University of North Carolina
  3. ^ Philip Hershkovitz,Living New World monkeys (Platyrrhini): with an introduction to Primates, University of Chicago Press, 1977, Vol. I, p. 16
  4. ^ Ankel-Simons, F. (2007). Primate Anatomy (3rd ed.). Academic Press. p. 394. ISBN 978-0-12-372576-9. 
  5. ^ FAS Clinical
  6. ^ Aldridge, Kristina; George, Ian D.; Cole, Kimberly K.; Austin, Jordan R.; Takahashi, T. Nicole; Duan, Ye; Miles, Judith H. (2011). "Facial phenotypes in subgroups of pre-pubertal boys with autism spectrum disorders are correlated with clinical phenotypes". Molecular Autism 2 (15). doi:10.1186/2040-2392-2-15.
  7. ^ Gabriel's Palace: Jewish Mystical Tales, p57
  8. ^ Babylonian Talmud; Niddah 30b