The philtrum, also known as the infranasal depression, is the vertical groove located in the midline between the base of the nose and the upper lip. This feature is bordered by two raised ridges, called philtral columns, which extend down to form the Cupid's bow of the upper lip. The length of the philtrum is the distance between the base of the nose and the upper lip's vermilion border. While the appearance of the philtrum varies among individuals due to genetics, its development during pregnancy is a critical process.
The Anatomy and Development of the Philtrum
The Philtrum's Features
The philtrum's distinct shape is created by the philtral columns. The area below the nose and above the upper lip can also be referred to as the upper cutaneous lip or ergotrid. The dimensions of the philtrum, including its length, width, and depth, are largely genetically determined.
Embryological Origin
The philtrum is formed early in pregnancy, around the second or third month, when different parts of the face merge. Specifically, the medial nasal processes and maxillary processes join together to create this central upper lip region. If these processes do not fuse properly, it can result in a cleft lip.
Function: A Vestigial Remnant in Humans
Why Do Humans Have a Philtrum?
For humans and most primates, the philtrum is considered a vestigial structure, meaning it is a remnant of an anatomical feature that had a greater purpose in our ancestors. Our sense of smell is less crucial for survival compared to many other mammals, so the original function of the philtrum is no longer essential.
The Philtrum in Other Mammals
In many other mammals, such as dogs and cats, the philtrum is functional. It's a groove that helps transport moisture from the mouth to the rhinarium (the wet part of the nose), keeping it moist. This moisture helps animals trap scent particles and enhances their sense of smell.
Associated Medical Conditions
Genetic Syndromes
The appearance of the philtrum can be an indicator of certain genetic conditions. A smooth or short philtrum is a characteristic facial feature of Fetal Alcohol Syndrome (FAS), which results from alcohol exposure during pregnancy. A prominent and short philtrum is also seen in Smith-Magenis syndrome, while a wider philtrum has been linked to autism spectrum disorders. A genetic evaluation may be recommended if a philtrum appears unusually long or deep.
Nasolabial Folds: A Point of Confusion
It is important not to confuse the philtrum with nasolabial folds, also known as "smile lines." These are the creases that run from the sides of the nose to the corners of the mouth. Unlike the philtrum, nasolabial folds are primarily associated with aging, loss of skin elasticity, and repeated facial expressions.
Cosmetic Procedures and Treatments
Various cosmetic procedures are available to address concerns about the appearance of the philtrum or surrounding areas, such as a long philtrum or deep nasolabial folds.
| Concern | Procedure/Treatment | Outcome | Type |
|---|---|---|---|
| Long Philtrum | Bullhorn Lip Lift | Surgically shortens the philtrum, lifting the upper lip for a more youthful look. | Surgical |
| Deep Nasolabial Folds | Dermal Fillers | Injected substances (like hyaluronic acid) plump the creases, reducing their depth. | Non-surgical |
| Aging Skin/Fine Lines | Retinoids | Topical application of this vitamin A derivative stimulates collagen and reduces fine lines over time. | Topical |
| Downturned Mouth Corners | Corner Lip Lift | A small incision near the mouth corners repositions the lip to give a lifted appearance. | Surgical |
| Overall Facial Rejuvenation | Thread Lifting | Threads with cogs are inserted to lift and tighten sagging tissue, which can improve the appearance of nasolabial folds. | Minimally Invasive |
Conclusion: More Than Meets the Eye
The philtrum, the skin between your nose and mouth, is a small but significant facial feature with developmental and evolutionary roots. While largely non-functional in humans, its appearance can provide valuable clues about underlying genetic or developmental conditions. Understanding the distinction between the philtrum and nasolabial folds is also important for individuals considering cosmetic treatments. Whether for medical diagnosis or aesthetic enhancement, the philtrum remains a noteworthy element of facial anatomy.
For further reading on the intricate process of facial development, you can explore the resources available on the National Institutes of Health website.
