Module 01 · Data Sheet
Lip anatomy by depth, not by diagram
Surface anatomy, layer anatomy and where the labial arteries actually sit — compartment by compartment, midline to commissure, in millimetres.
≈78%
Labial arteries lying submucosal (posterior) rather than subcutaneous
4–6 mm
Typical depth of the SLA from the vermilion surface
≤2.5 mm
Depth ceiling for the subdermal/superficial vermilion safe corridor
10–15 mm
Distance from the commissure to the labial artery origin
Surface anatomy — what you can see and mark
Vermilion border / white roll
The light-catching ridge. Product sits intradermal to subdermal — 0.5–2 mm, never deeper.
Philtral columns & dimple
Paired subdermal ridges converging on Cupid’s bow. Depth 1–2 mm; deeper placement flattens rather than defines.
Cupid’s bow
The double peak. Its height, not its volume, reads as youth.
Wet–dry line (Glogau–Klein point)
The surface marker that most closely tracks the labial artery beneath it.
Central & lateral tubercles
Three upper, two lower. Volume belongs here, superficially, or nowhere.
Oral commissure & modiolus
A muscular junction, not lip tissue. Skin-plane work only.
Compartment map & layer anatomy
Select a compartment. The cross-section redraws with the artery window for that zone against a fixed 0–9.5 mm depth ruler.
upper lip · artery depth by compartment
lower lip · artery depth by compartment
upper lip
High consequenceZ2 — Medial body
- Surface landmark
- Between the philtral column and the mid-pupillary line (≈8–15 mm from midline)
- Artery depth
- 4–6 mm · Submucosal in ≈75–80%; intramuscular in ≈15–20%
- Vessel
- Main SLA trunk, usually at or just deep to the wet–dry (Glogau–Klein) line.
- Working corridor
- Vermilion body 1.5–2.5 mm from the dry vermilion surface; avoid needle angles that drive posteriorly.
- Note
- This is the classic “plump the body” zone and the commonest site of intra-arterial events in the upper lip.
Table 1 · Layer-by-layer depths
| Layer | Depth (mm) | Character | Vascular content |
|---|---|---|---|
| Vermilion epithelium / skin | 0–0.6 | Thin, non-keratinised over the vermilion; keratinised above the white roll. No fat pad over the dry vermilion. | — |
| Subdermal / superficial areolar plane | 0.6–2 | The plane of vermilion hydration, white-roll definition and philtral column support. Product here is visible, mobile and low risk. | Only terminal arterioles — arterial catastrophe is uncommon but bruising is not. |
| Orbicularis oris — pars marginalis / peripheralis | 2–5.5 | The muscular body. Pars marginalis rolls the vermilion outwards; pars peripheralis is the sphincteric ring above and below. | Intramuscular labial artery variants (≈17–22% of upper lips, more often laterally). |
| Submucosal plane (labial glands) | 5.5–8 | Minor salivary glands, loose areolar tissue — and the usual home of the labial arteries. | Superior/inferior labial artery in the majority of specimens (≈70–80% submucosal). |
| Wet mucosa | 8–9.5 | Inner surface. Total lip thickness at rest is commonly 8–12 mm, thinner laterally, thickest at the central tubercle. | — |
Table 2 · Artery depth by compartment
| Lip | Compartment | Distance from midline | Artery depth | Dominant plane | Consequence |
|---|---|---|---|---|---|
| upper | Z1 — Philtral / central tubercle | Philtral columns, Cupid’s bow, central tubercle (0–8 mm from midline) | 3.5–5.5 mm | Submucosal, posterior third of the lip body | Moderate |
| upper | Z2 — Medial body | Between the philtral column and the mid-pupillary line (≈8–15 mm from midline) | 4–6 mm | Submucosal in ≈75–80%; intramuscular in ≈15–20% | High |
| upper | Z3 — Lateral body | Mid-pupillary line to 10 mm short of the commissure (≈15–22 mm from midline) | 5–7 mm | Increasingly intramuscular as you travel laterally | High |
| upper | Z4 — Commissure / modiolus | Within 10 mm of the oral commissure | 6–8.5 mm | Deep, intramuscular, adjacent to the modiolar convergence | Critical |
| lower | Z1 — Central lower tubercles | Midline sulcus and the paired central tubercles (0–8 mm from midline) | 4–6 mm | Submucosal | Moderate |
| lower | Z2 — Medial body | ≈8–15 mm from midline | 4.5–6.5 mm | Submucosal in ≈60–70%; intramuscular in ≈25–30% | High |
| lower | Z3 — Lateral body | ≈15–22 mm from midline | 5.5–7.5 mm | Intramuscular / deep submucosal | High |
| lower | Z4 — Commissure / modiolus | Within 10 mm of the oral commissure | 6.5–9 mm | Deep intramuscular, at the modiolus | Critical |
Table 3 · The vessels that matter
Superior labial artery (SLA)
- Origin
- Facial artery, 10–15 mm lateral/superior to the oral commissure
- Plane distribution
- Submucosal ≈70–80% · Intramuscular ≈15–20% · Subcutaneous ≈2–5%
- Mean depth
- ≈4–6 mm from the vermilion surface (shallower medially, deeper laterally)
- Course
- Runs horizontally at or just deep to the wet–dry line, posterior to the muscle in most specimens, arcading across the midline.
Inferior labial artery (ILA)
- Origin
- Facial artery, 10–20 mm lateral/inferior to the commissure; may arise as a common labial trunk
- Plane distribution
- Submucosal ≈60–70% · Intramuscular ≈25–30% · Subcutaneous ≈5%
- Mean depth
- ≈4.5–7 mm from the vermilion surface
- Course
- Higher anatomical variability than the SLA — absent, duplicated or replaced by horizontal labiomental branches in a substantial minority.
Facial artery (perioral segment)
- Origin
- External carotid
- Plane distribution
- Deep to the platysma/depressor anguli oris, then subcutaneous as it ascends
- Mean depth
- ≈6–10 mm at the mandibular border, rising to ≈4–5 mm near the alar base
- Course
- The commissure is a junction, not a lip — the vessel is larger and the consequences of cannulation reach the nose and eye.
Table 4 · Injection planes and what each one buys you
| Plane | Depth | Indication | Vascular consequence |
|---|---|---|---|
| Intradermal | 0.5–1.0 mm | Vermilion border blur, fine perioral rhytides, skin-quality boosters | Low |
| Subdermal | 1.0–2.5 mm | White roll, philtral columns, Cupid’s bow, commissure support | Low |
| Superficial vermilion body | 1.5–3.0 mm | Hydration, eversion, tubercle definition | Moderate |
| Intramuscular (orbicularis) | 3.0–5.5 mm | Rarely indicated for filler; toxin territory (micro-dose, ≤2 mm above the border) | High |
| Submucosal | 5.5–8.0 mm | Volumising “from behind”; the artery’s preferred address | Critical |
Depth is meaningless without entry angle and vector
A 4 mm needle entered at 90° from the vermilion surface finishes in the submucosal plane. The same needle at the same point, entered at 30° and advanced 5 mm, stays in the superficial vermilion. Record depth, angle and travel together — a depth number on its own describes nothing reproducible. Lateral compartments are thinner, so identical geometry lands deeper relative to the vessel.
How to read these numbers
Depths are pooled averages from cadaveric dissection, CT-angiography and Doppler ultrasound series. Published means differ by measurement plane (skin surface vs mucosal surface vs vermilion), by fixation method and by cohort. Treat each range as a probability window, not a boundary: labial arteries are duplicated, absent or displaced in a meaningful minority of patients, and prior filler distorts every plane on this page. Ultrasound is the only way to know the depth in the patient in front of you.
Source literature
- Cotofana S, et al. The Anatomy of the Facial Vein and the Superior Labial Artery: Implications for Filler Injections. Aesthetic Surgery Journal.
- Tansatit T, Apinuntrum P, Phetudom T. A Typical Pattern of the Labial Arteries with Implication for Lip Augmentation with Injectable Fillers. Aesthetic Plastic Surgery.
- Lee SH, et al. Topographic Anatomy of the Superior Labial Artery for Dermal Filler Injection. Plastic and Reconstructive Surgery.
- Kim YS, et al. Ultrasonographic Evaluation of the Labial Arteries in Living Subjects. Dermatologic Surgery.
- Cotofana S, Lachman N. Anatomy of the Facial Fat Compartments and Their Relevance in Aesthetic Surgery. JDDG.
- Scheuer JF, et al. Anatomy of the Facial Danger Zones: Maximizing Safety During Soft-Tissue Filler Injections. Plastic and Reconstructive Surgery.