The philtrum (Greek: philtron = love potion [ancient Greeks considered the philtrum to be one of the most erogenous spots on the human body]) is a vertical groove in the midline portion of the upper lip bordered by two lateral ridges or pillars. It lies between the base of the nose (subnasale) and the vermilion border (labiale superius), which is also designated as the nasolabial distance. The lower end of the groove and the ridges form the central portion of the Cupid's bow of the vermilion [see Carey et al., ].
Measurement of the nasolabial distance is inaccurate, because determination of short distances between soft tissue points is difficult and may be misleading [Méhes, ; Ward and Jamison, ]. Several surveys of normal values of philtral length in various population samples have been published. For details see a selection of such papers listed in Table I.
|Table I. Normal Values for Philtrum Length (Selected Studies)|
|Age of subjects/method||Country||References|
|13-42 weeks of gestation/sonography||Israel||Gull et al. |
|28-42 weeks of gestation/calipera or blunt compasses||Hungary||Méhes |
|27-41 weeks of gestation/caliper||Japan||Fok et al. |
|37-41 weeks of gestation/caliper||Japan||Tateishi and Kajii |
|1 month to 15 years/calliper||Japan||Igarashi and Kajii |
|1-18 years/caliper||North America||Farkas et al. |
|Birth to 14 years||USA||Feingold |
|Birth to 12 years/photo-anthropometry||Germany||Stengel-Rutkowski et al. |
|Birth to 97 years/rigid transparent caliper||Switzerland||Zankl et al. |
|a Caliper = sliding caliper in each case.|
Ideally the philtral length is measured with sliding calipers, but in practice it is typically performed with a transparent ruler [Hall et al., ]. Measurements should be performed in a neutral position, since facial expression can alter the landmarks. In addition to difficulties of measurement, significant ethnic, age and sex variations should also be considered [Stengel-Rutkowski et al., ].
Characteristics of the philtrum may be classified into quantitative traits and qualitative features: