The labial arteries are a pair of blood vessels that supply the upper and lower lips, branching off the facial artery as it travels up alongside the mouth. The superior labial artery feeds the upper lip, while the inferior labial artery feeds the lower. Both are small, averaging about 1.3 mm in diameter at their origin, yet they carry enough blood flow to make the lips one of the most vascular structures on the face. That rich blood supply is why lips heal quickly after injury, blush easily in the cold, and bleed with surprising vigor when cut.
Where Exactly Do They Run
Both labial arteries branch from the facial artery near the corner of the mouth. The superior labial artery typically branches just above the corner, while the inferior labial artery branches just below it. From there, each vessel curves toward the midline of its respective lip, where it meets and joins (anastomoses with) its partner from the opposite side, forming a vascular loop that keeps blood flowing even if one side is interrupted.
Most of the time, these arteries take a winding, tortuous path rather than running in a straight line. In a large cadaveric study, the superior labial artery followed a twisted course in nearly 80% of specimens. That tortuous shape matters clinically: it means the vessel can be unexpectedly close to the surface at one point and deeper at another, even within the same lip.
In terms of depth, the most common location for both arteries is the submucosal plane, the layer of tissue sitting just beneath the inner lining of the lip and above the orbicularis oris muscle. An ultrasound study found that roughly 59% of labial arteries sat in that submucosal layer, about 36% ran within the muscle itself, and only around 5% were in the subcutaneous layer closer to the skin surface. The superior labial artery averaged about 5.6 mm deep from the outer lip surface, while the inferior labial artery sat about 5.2 mm deep. A separate cadaveric dissection measured the superior labial artery at about 4.5 mm deep along the upper lip, running between the oral mucosa and the orbicularis oris muscle just above the junction where the pink of the lip meets the inner mucosa.
A Vessel That Varies Enormously From Person to Person
If there is one thing the anatomical literature hammers home about the labial arteries, it is their variability. Unlike some blood vessels that follow the same path in nearly everyone, the labial arteries differ in their branching pattern, their course through the lip, and even whether they are present at all.
The superior labial artery is the more consistent of the two, showing up in roughly 87% of cadavers in one study. The inferior labial artery was present in about 78%. When the inferior labial artery was present, it showed two distinct behaviors: a smaller fraction followed a “typical” course running along the vermilion border of the lower lip, while the majority took a horizontal path through the middle of the lower lip area, a pattern called the horizontal labiomental artery pattern. A literature review confirmed that the labial arteries display wide variability in their path, presence, and location across individuals. A separate study identified four distinct distribution patterns for the superior labial artery alone, with the most common type accounting for about 70% of cases.
A meta-analysis combining cadaveric and imaging data found that while the arteries reliably meet at the midline, their position becomes much less predictable in the paramedian zones, the areas off to either side of center. This positional scatter has direct consequences for anyone working near the lips, whether with a scalpel, a needle, or a suture.
Why Lip Fillers Make the Labial Arteries So Clinically Relevant
The explosion of injectable lip fillers over the past two decades has turned the labial arteries from a niche anatomy topic into an urgent safety concern. Hyaluronic acid filler, the most popular material for lip volumization, is injected directly into the lip tissue. If a needle or cannula punctures or compresses a labial artery, the consequences range from a localized bruise to tissue death and, in rare but devastating cases, blindness.
The risk stems from the arteries’ position. Because most labial arteries run in the submucosal plane, and filler is typically injected into or near that same layer, the needle and the artery occupy overlapping territory. Ultrasound mapping of healthy volunteers showed that the superior and inferior labial arteries are spread across all parts of the oral mucosa, leading researchers to recommend very superficial injection approaches to reduce the chance of hitting a vessel. One technique specifically designed to stay in a safer zone uses a short 4-mm needle to place filler into the subcutaneous plane of the lip, above the depth where most labial arteries sit.
Ultrasound guidance has emerged as a tool to map the arteries before injecting. Because the vessels vary so much from person to person, even an injector with detailed anatomical knowledge cannot reliably predict where a given patient’s labial arteries lie without imaging. Pre-procedural ultrasound can reveal the artery’s depth, course, and any unusual branching, allowing the clinician to plan injection points that avoid the vessel.
What Goes Wrong When Filler Hits an Artery
Most filler complications in the lips are mild: bruising, swelling, temporary lumpiness. But vascular compromise, where filler blocks blood flow through the labial artery or a connected vessel, is the complication that keeps practitioners up at night. When filler material enters an artery or compresses one from outside, it can cut off the blood supply to the downstream tissue, causing skin blanching that progresses to tissue necrosis if not treated quickly. Beyond mild complications, vascular blockage, infections, and delayed-onset nodules can cause substantial harm to the patient.
The most feared complication is not local but distant. The labial arteries connect, through a network of small branches, to the blood supply of the nose and, via the ophthalmic artery, to the eye. Under certain conditions, filler material injected into the labial artery can travel backward (retrograde embolism) through these connections and block blood flow to the retina, causing partial or complete blindness. Research has verified that persistent connections between facial arteries and the eye’s blood supply can serve as channels for filler emboli to reach the globe. These events are rare, but they are not theoretical: case reports have documented them, and the anatomy explains how they happen.
Treatment for vascular compromise typically involves immediate injection of hyaluronidase, an enzyme that dissolves hyaluronic acid filler, directly into the affected area. Ultrasound can help identify whether the filler has entered the vessel or is compressing it from outside, guiding the hyaluronidase injection in real time for more precise treatment.
The Labial Artery in Reconstructive Surgery
Surgeons rely on the labial arteries for more than just avoiding them. In reconstructive procedures for lip defects, whether from cancer resection, trauma, or congenital conditions, the labial artery serves as the lifeline for tissue flaps used to rebuild the lip.
The most well-known example is the Abbé flap (also called the Sabattini-Abbé cross-lip flap), a technique used when a significant portion of one lip needs to be replaced. A wedge of tissue is taken from the opposite lip and rotated into the defect, staying attached to the labial artery as its blood supply. For instance, a flap taken from the left lower lip would be fed by the right superior labial artery. The labial arteries sit at the level of the vermilion border, and the surgeon must carefully dissect the orbicularis oris muscle at that level to preserve the vascular pedicle deep to the muscle. The flap remains connected for roughly two to three weeks while new blood vessels grow into it from the surrounding tissue, after which the pedicle is divided and the connection to the donor lip is released.
This technique works precisely because the labial arteries are reliable enough at the midline and robust enough to support a tissue flap on their own. The artery’s tortuous course actually helps here, providing a bit of slack that allows the flap to be rotated without kinking the vessel.
Trauma and Unexpected Bleeding
The labial arteries sit close to the surface in a part of the body that takes a lot of incidental punishment: biting the lip, dental work, sports injuries, falls. When one of these vessels is severed or torn, it can bleed with a force that surprises anyone who thinks of a lip wound as minor.
A published case described a patient who developed pulsatile arterial bleeding from the lip after a dental appointment. Simple packing and tranexamic acid-soaked gauze failed to control the hemorrhage, and the patient required figure-of-eight sutures placed in a procedure room to stop the arterial bleed. The point of the report was not that the situation was exotic but that it was under-recognized: clinicians who expect lip bleeding to stop with pressure alone may be caught off guard by a lacerated labial artery.
Delayed hemorrhage is another scenario. A lip laceration that is sutured or seems to heal normally can later develop a pseudoaneurysm, a bulging weak spot in the damaged arterial wall that eventually ruptures. A case report documented exactly this sequence after a traumatic lower lip laceration: initial repair, apparent healing, then delayed bleeding from a pseudoaneurysm of the inferior labial artery. These cases are uncommon, but they underline that any lip wound deep enough to reach the submucosal layer has the potential to involve a labial artery.
For anyone managing a lip laceration at home or in the field, the practical takeaway is straightforward: if direct pressure does not stop lip bleeding within ten to fifteen minutes, or if the bleeding is visibly pulsatile (spurting in time with the heartbeat), seek medical attention. The labial artery may need to be sutured directly.
Caliber-Persistent Labial Artery
Not every labial artery concern involves injury or injection. A condition called caliber-persistent labial artery (CPLA) is a vascular anomaly in which the artery enters the submucosal tissue of the lip without shrinking in diameter as it normally would. The result is a visible or palpable pulsating bump on the lip, usually the lower lip, that can be mistaken for a tumor, cyst, or mucocele.
CPLA is benign, but the mimicry matters. Clinicians who do not recognize it may order a biopsy or attempt surgical removal, which can trigger severe bleeding because the oversized artery is fully functional. As one case series emphasized, excisional biopsy or surgical removal of these lesions can have a dangerous outcome with profuse hemorrhage. The condition is typically diagnosed by its pulsatile nature and its tendency to blanch when compressed, and Doppler ultrasound can confirm blood flow through the lesion without the need for cutting.
CPLA tends to show up in older adults and is thought to result from age-related changes in the arterial wall, where the vessel loses its normal taper as it branches into smaller caliber segments. It requires no treatment if the patient is asymptomatic, though some people seek care because the pulsating lump is cosmetically bothersome or anxiety-provoking.
Imaging the Labial Arteries
For decades, knowledge of labial artery anatomy came almost entirely from cadaveric dissection. That changed with high-frequency ultrasound, which can visualize these small vessels in living patients in real time. Ultrasound studies have done much to refine our understanding of where the arteries actually sit. A study using ultrasonography in 60 healthy volunteers mapped the positions of the superior and inferior labial arteries relative to the vermilion border, finding the vessels distributed throughout the oral mucosa and not confined to a single predictable depth or path.
Color Doppler ultrasound can show blood flow within the vessel, helping distinguish the artery from surrounding tissue, and pulsed-wave Doppler can confirm the arterial waveform. This matters in two contexts: pre-procedural planning for fillers or surgery, where knowing the exact location of the artery reduces the risk of vascular injury, and diagnosis of conditions like caliber-persistent labial artery, where imaging confirms the vascular nature of a suspicious lip lump without an invasive biopsy.
CT angiography and MR angiography can also visualize the labial arteries, but these modalities are overkill for most clinical situations. Ultrasound is portable, inexpensive, radiation-free, and can be performed chairside in a dermatology or plastic surgery office. Its main limitation is operator dependence: the arteries are small, and identifying them requires practice and a high-frequency linear probe.
The Labial Arteries in Other Primates
The labial arteries are not unique to humans. Research on the arterial supply of the mouth and jaw in neotropical primates found that the inferior and superior labial arteries are present in multiple primate genera, and the overall vascular pattern of the mandible and maxilla resembles the human arrangement. The study noted that while the general blueprint is similar across species, notable variations exist in the specific branching of these vessels from genus to genus. This shared anatomy reflects the common evolutionary heritage of primate faces and suggests that the basic labial arterial supply is an ancient feature of primate facial vascularization, not a recent human-specific development.
1PubMed Central. Facial artery: anatomical variations in the perioral region in cadavers РSection: Results 2PubMed. Anatomy of the Superior and Inferior Labial Arteries Revised: An Ultrasound Investigation and Implication for Lip Volumization РSection: RESULTS 3PubMed. A typical pattern of the labial arteries with implication for lip augmentation with injectable fillers РSection: RESULTS 4JPRAS Open. Anatomical variations of the superior labial branch of the facial artery РSection: Abstract 5PubMed. Anatomical Variations in the Course of Labial Arteries: A Literature Review РSection: RESULTS 6PubMed Central. Anatomical Distribution of the Superior and Inferior Labial Arteries: A Cadaveric, Systematic Review, and Meta-analysis Study РSection: RESULTS 7PubMed Central. Lip Augmentation Using Hyaluronic Acid Filler and a 4-mm Needle: A Safer, More Natural, and Predictable Approach РSection: Abstract 8PubMed. Positional relationship of superior and inferior labial artery by ultrasonography image analysis for safe lip augmentation procedures 9PubMed. Verification of Embolic Channel Causing Blindness Following Filler Injection РSection: CONCLUSION 10Operative Techniques in Otolaryngology-Head and Neck Surgery. Lip reconstruction using the Sabattini-Abb̩ cross-lip flap РSection: Technique 11Academic Medicine & Surgery. Labial Artery Hemorrhage After a Dentist Appointment РSection: CASE PRESENTATION 12PubMed Central. Post Traumatic Inferior Labial Artery Pseudoaneurysm After Lip Laceration: Case Report РSection: Abstract 13PubMed Central. Caliber-persistent labial artery: report of 3 cases