In short. Lip anatomy is usually described in four parts: the vermilion, the white roll, the philtrum and the orbicularis oris. The vermilion itself has a dry and a wet surface, and a plan aimed at the wrong part changes nothing the patient can see.
Key points
- The vermilion has a dry surface facing out and a wet surface facing the teeth.
- The white roll is a raised ridge, and a faded border is often this ridge flattening.
- Philtrum length decides whether an upper lip looks long, and it is skin rather than volume.
- Adding material cannot change philtrum length; relaxing the muscle can change position.
- The lips are among the best supplied areas of the face, which is why arterial injection is an emergency.
What are the two surfaces of the vermilion?
The vermilion is the coloured part of the lip, and it is two surfaces. The dry vermilion faces out and dries in the air; it has no hair follicles and no sweat glands, which is why it cracks rather than flakes. The wet vermilion faces the teeth and is kept moist by saliva.
The white roll and the border
Between the vermilion and the skin runs the white roll, a raised ridge that gives the lip its edge. A border that has faded is usually this ridge flattening rather than the lip losing height, and the two are treated differently.
What does the philtrum determine?
Above the upper lip, the skin runs from the base of the nose to the border, with two faint vertical columns and a shallow groove between them. This is the philtrum, and its length is the measurement that decides whether an upper lip looks long. Length here belongs to skin, not to volume, and it is the one thing on this site that adding material cannot change. Where the space is long and the vermilion is adequate, the finding is position rather than tissue.
The muscle that moves all of it
The orbicularis oris encircles the mouth and works as a sphincter, closing and pursing the lips. Its fibres also turn the vermilion outwards as it contracts. Other muscles converge at the corner of the mouth, and two groups matter here: those that lift the upper lip and decide how much gum shows when you smile, and those that pull the corners down. Both are findings about position, and both answer to relaxing the muscle rather than to adding volume.
Why the blood supply belongs in the decision
The lips are among the best supplied areas of the face. That is why a lip heals quickly, and it is also why the lip is one of the places where material injected into an artery rather than beside it is a recognised emergency. The same anatomy explains why the two routes differ as much as they do. An injectable adds material into a mobile, well-supplied layer and can be dissolved. An operation removes skin or tissue and cannot put it back.
Three questions that organise a lip assessment
Four parts answer three questions: is there enough tissue, where does the border sit, and what is the muscle doing. Volume, position and muscle are separate findings, and a plan aimed at the wrong one changes nothing the patient can see.
| Structure | What it is | What it does | What it explains |
|---|---|---|---|
| Dry vermilion | The coloured surface facing out, without hair follicles or sweat glands | Dries in the air | Why the lip cracks rather than flakes |
| Wet vermilion | The coloured surface facing the teeth | Kept moist by saliva | Why the lip has two surfaces that behave differently |
| White roll | A raised ridge between the vermilion and the skin | Gives the lip its edge | Why a faded border can be the ridge flattening rather than height loss |
| Philtrum | Skin from the base of the nose to the border, with two faint columns and a shallow groove | Its length decides whether an upper lip looks long | Why adding material cannot change a long upper lip |
| Orbicularis oris | A sphincter that encircles the mouth | Closes and purses the lips and turns the vermilion outwards | Why some position findings answer to relaxing the muscle |
| Muscles at the corner | Two groups, one lifting the upper lip and one pulling the corners down | Decide how much gum shows when you smile and where the corners sit | Why gum show and downturned corners are not volume problems |
| Lip arteries | The lips are among the best supplied areas of the face | They let a lip heal quickly | Why material injected into an artery rather than beside it is a recognised emergency |
When does a lip finding need medical review?
A sore, ulcer or white patch on the lip that has not healed in a few weeks needs review. So do severe pain, blanching or mottled skin during or after a lip injection, and a lip that is numb, or a mouth that does not close, after an operation.
Sources
Internal links
Frequently asked questions
What is the white roll, and why does it matter?
It is the raised ridge where the coloured part of the lip meets the skin, and it is the structure that makes a lip read as a lip rather than as a soft area. It catches light along its length, so a lip with a clear roll looks defined even when it is not especially full. It is also the structure that flattens first with age, which is why a border that has faded can be restored without making the lip noticeably larger.
Why does the upper lip have a philtrum?
It is where the two sides of the upper lip fuse before birth, which is why the two faint columns and the groove between them run vertically and why the groove sits exactly at the midline. It has no function in an adult mouth. Its importance here is that it is skin, not tissue, so its length is the measurement that decides whether an upper lip looks long, and it is the one thing on this site that added volume cannot change.
Does the lip really have its own blood supply?
It does. Arteries run on each side of the mouth between the muscle and the moist lining, and the supply is generous, which is why a cut lip bleeds freely and heals quickly. The same anatomy is why the lip is one of the places where an injection that enters an artery rather than passing beside it is a recognised emergency, and why practitioners who treat lips are expected to know what they would do if that happened.
Risks & Limitations
- A dissolvable gel filler can be broken down with an enzyme. Skin or tissue removed by an operation cannot be put back.
- Bruising and swelling after a lip injection are common and usually settle over one to two weeks.
- Repeated filler over years can accumulate in the lip, and dissolving may not return it to its untreated state.
- Every operation on the lip leaves a scar, and the lines above the border and the way the mouth closes can change.
When to Seek Care
- Severe pain, blanching or mottled skin during or after a lip injection, or a change in vision.
- A sore, ulcer or white patch on the lip that has not healed in a few weeks.
- A lip that is numb, or a mouth that no longer closes, after an operation.
- Fever with spreading redness, warmth or discharge, or a wound that opens.
References & Further Reading
- American Society of Plastic Surgeons (ASPS) — procedure and safety guidance
- National Institute for Health and Care Excellence (NICE, UK) — relevant guidance
- Cochrane Library — systematic reviews
- Chinese Medical Association Plastic Surgery Branch — clinical guidance
This page is patient education, not medical advice, and it does not cite individual studies. Discuss your own case with a qualified clinician. To arrange an assessment at Chongqing West District Hospital, see Contact & Consultation.