what is a phildrum?
Hi Heather, thanks for your great question.
The philtrum (Latin philtrum, Greek φίλτρον philtron), is a vertical groove in the middle area of the upper lip, common to many mammals, extending from the nose to the upper lip. Technically referred to as the medial cleft ...
See link for more information: http://en.wikipedia.org/wiki/Philtrum