The indent above the lip is a common anatomical feature known as the philtrum. This distinct vertical groove is located in the midline of the face, positioned between the base of the nose and the upper lip. The philtrum is present in almost all individuals, contributing to the unique appearance of the human face and being a natural part of facial development.
What is the Philtrum?
The philtrum is a vertical groove found at the center of the upper lip, directly beneath the nasal septum. This groove is typically bordered by two raised ridges, often referred to as philtral columns, which extend downwards to meet the curve of the upper lip, forming the central portion of what is known as the Cupid’s bow. Its anatomical location connects the nose to the vermilion border of the upper lip.
This feature is shared among humans and many other mammals, although its appearance and potential functions can differ across species. In humans, it is primarily a visible indentation, contributing to facial structure and balance. The philtrum’s physical characteristics, such as its depth and width, can vary significantly from person to person.
The Philtrum’s Role and Formation
The philtrum’s existence in humans is a result of a process during embryonic development. It forms around the sixth to eighth week of gestation as different facial segments fuse together. Specifically, the medial nasal prominences, which are part of the developing face, merge in the midline to create this central groove. This fusion process is important for the proper formation of the middle part of the face, including the philtrum, the primary palate, and the central upper lip.
The philtrum serves as a visible reminder of this intricate developmental event. While it does not possess a known active function in adult humans, its formation is intertwined with the development of other facial structures. It may contribute to the flexibility of the upper lip for expressions and speech, though its primary significance lies in its developmental origin.
Normal Variations of the Philtrum
The appearance of the philtrum can vary naturally among individuals, and a wide range of forms are considered typical. Some people have a philtrum that is deep and pronounced, with distinct philtral columns. Conversely, others may have a flatter or less defined philtrum, which is a common variation. These differences are often influenced by genetic factors and contribute to the diversity of human facial features.
In some situations, an unusually smooth, flat, or absent philtrum can be associated with certain developmental conditions, such as Fetal Alcohol Syndrome (FAS). Most variations in philtrum depth or prominence are part of normal human diversity and do not indicate any underlying health concerns.