Superior Labial Research Articles

Three-Dimensional Computed Tomography Scanning Study of the Superior Labial Artery in Chinese Individuals for Assessing Filler Injection Safety.

Lip filler injection is one of the most common minimally invasive cosmetic procedures involving the face; however, vascular complications are not uncommon. The aim of this study was to investigate the anatomy of the superior labial artery (SLA) and provide precise topographic information for dermal filler injection into the lips. Computed tomography (CT) scans of 52 cadaveric heads injected with lead oxide were obtained. We then used Mimics software to construct 3D images of the SLA described by a coordinate system based on the bilateral external auditory canal and the left orbit. This study aimed to classify the SLA in the Han Chinese population, measure its diameter at specific points, and determine the thickness of the lip at those points. Ultimately, we utilized a thermal imaging technique to illustrate the course and depth of the SLA within the lip. The objective of this study was to provide safe guidance for clinical injections. In this study, the SLA was successfully identified in all cadavers. The mean overall diameter of the superior labial arteries was 1.36±0.28 mm. The superior labial artery showed a general course from deep to shallow with an average depth of 5.68±1.68 mm from the oral commissure to the midline. There are anatomical differences in the superior labial arteries among Chinese people. Furthermore, 3D CT images can digitally elucidate the exact positions of the superior labial artery via a coordinate system, improving the safety of upper lip filler injections in clinical settings. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

The branching patterns and termination points of the facial artery: a cadaveric anatomical study.

The facial artery is an important blood vessel responsible for supplying the anterior face. Understanding the branching patterns of the facial artery plays a crucial role in various medical specialties such as plastic surgery, dermatology, and oncology. This knowledge contributes to improving the success rate of facial reconstruction and aesthetic procedures. However, debate continues regarding the classification of facial artery branching patterns in the existing literature. We conducted a comprehensive anatomical study, in which we dissected 102 facial arteries from 52 embalmed and formaldehyde-fixed Vietnamese cadavers at the Anatomy Department, University of Medicine and Pharmacy, Ho Chi Minh City, Vietnam. Our investigation revealed eight distinct termination points and identified 35 combinations of branching patterns, including seven arterial branching patterns. These termination points included the inferior labial artery, superior labial artery, inferior alar artery, lateral nasal artery, angular artery typical, angular artery running along the lower border of the orbicularis oculi muscle, forehead branch, duplex, and short course (hypoplastic). Notably, the branching patterns of the facial artery displayed marked asymmetry between the left and right sides within the same cadaver. The considerable variation observed in the branching pattern and termination points of the facial artery makes it challenging to establish a definitive classification system for this vessel. Therefore, it is imperative to develop an anatomical map summarizing the major measurements and geometric features of the facial artery. Surgeons and medical professionals involved in facial surgery and procedures must consider the detailed anatomy and relative positioning of the facial artery to minimize the risk of unexpected complications.

THE RELATIONSHIP BETWEEN THE LOCALIZATION OF LABIAL ARTERIES USING ULTRASONOGRAPHY FOR LIP AUGMENTATION PROCEDURES: A LITERATURE REVIEW

Introduction:Lips, being among the most prominent facial features, have hyaluronic acid fillers as one of the most commonly used procedures to enhance their shape and volume. However, these procedures can present complications, many of which are relatedto injury to the labial arteries. The superior labial artery (SLA) and inferior labial artery (ILA) of the lips originate from the facial artery and cross various layers of the lips. Objective: The aim of this study is to conduct a literature review on the relationship between the localization of the superior and inferior labial arteries using ultrasonography as a method in the context oflip augmentation. Methodology: For that, a search was conducted in the "Pubmed'' database using the descriptors “labial artery anatomy” AND “ultrasonography” in English, considering articles published in the last 5 years. Finding 23 results, of which 3 articles were selected, including clinical research articles and excluding the ones that didn't fit the scope of this work. Literature Review:The analyzed studies presented conflicting results regarding the location of labial arteries, differing in their recommendations for injection sites, with a preference for superficial locations in the mucosal and submucosal planes as the safest locations. All of them used ultrasonography to obtain more precise numbers on artery positioning.Conclusion:As suggested by the analyzed studies, when performing various non-invasive cosmetic procedures, ultrasound-guided injections minimize the occurrence of side effects and can provide good safety and efficiency.

Facial artery: anatomical variations in the perioral region in cadavers.

In recent years, there has been an increase in reports of perioral vascular complications resulting from filler injections, such as necrosis of the lip or alar rim, occlusion, and in severe cases, blindness. Conversely, the use of perioral arterial flaps is becoming more prevalent in the treatment of cleft lips, cancer, and trauma. A thorough understanding of perioral arteries is essential to minimize complications and maximize the success of these flaps. However, the course of the facial artery (FA) in the perioral region remains incompletely understood. The aim of this study was to describe the variations of the FA in the perioral region. We dissected 52 embalmed and formaldehyde-fixed Vietnamese cadavers. We then studied the size and distribution of perioral arteries in 102 specimens. The superior labial artery (SLA) was the most common branch, occurring in 87.25% of cadavers, followed by the inferior labial artery (ILA) at 78.43%. The SLA primarily originated above the mouth corner (cheilion), accounting for 91.01% of cases, and predominantly exhibited a tortuous course within the submucosa (78.65%). The ILA's branching pattern varied, but it was primarily located below the cheilion (91.25%). The ILA also followed a twisted path, generally within the submucosa. The ILA exhibited two patterns: the typical pattern, distributed at the vermilion border of the lower lip (8.82%), and the horizontal labiomental artery pattern, which ran horizontally in the middle of the lower lip area (69.61%). At their origin, the SLA and ILA had average external diameters of 1.29 mm and 1.28 mm, respectively. Numerous anatomical variations in the FA in the perioral region were found. A detailed anatomic description, suggested landmarks, and angiography before the procedure will be useful to help doctors avoid complications.

A Retrospective Study on the Reconstruction of Nasal Septal Mucosal Defects after Asian Rhinoplasty.

Nasal septal mucosal defects following rhinoplasty in Asian patients are uncommon complications. However, the reconstruction of such defects presents a challenging task in plastic surgery. The aim of this study was to present comprehensive surgical strategies for the reconstruction of nasal septal mucosal defect after rhinoplasty. Thirteen cases presenting with nasal septal mucosal defects between January 2016 and October 2021 were retrospectively reviewed. The size, location, and severity of the defect as well as the extent of cartilage exposure were taken into consideration during evaluation, and surgical approaches were employed for repair accordingly. Patient satisfaction was evaluated using a questionnaire with visual analog scale (VAS) and nasal obstruction symptom evaluation scale (NOSE). The average postoperative follow-up period in this study group was 10.15 months. Reconstruction of nasal septal mucosal defects resulted in successful treatment for all patients. There was no evidence of flap failure or nasal valve stenosis. All patients were satisfied with the reconstruction outcome. The successful application of surgical techniques for nasal septal mucosal defects after rhinoplasty requires comprehensive consideration. The utilization of the retrograde-flow superior labial artery mucosal flap appears to be a secure, efficient, and effective technique for nasal septal mucosal defect reconstruction in rhinoplasty, particularly in cases with cartilage exposure. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Vascular Occlusion in the Lips: The Importance of Rapid Identification and Early Treatment

Cutaneous ischemia, caused by vascular occlusion, is one of the most feared adverse events for clinicians resulting from the injection of Hyaluronic Acid (HA). An early intervention with application of Hyaluronidase (HYAL) will lead to the successful reversal of the isquemic condition - which might be severe and brings serious consequences to the patient. The authors report a case of injection of HA in the labial region, which resulted in a sub occlusion of the superior labial artery in which degradation was performed with HYAL at different time points. This study evaluates one of the side effects of using HA fillers in order to enable early diagnosis and treatment, and reduce morbidity and sequelae among patients.

Distribution patterns of infraorbital nerve branches and risk for injury

BackgroundDuring oral and head and neck surgery, oral vestibular incisions may require a transverse incision on the upper lip mucosa, resulting in possible sensory disturbances in the area innervated by infraorbital nerve (ION) branches. Although sensory disturbances are attributed to nerve injuries, anatomy textbooks have not showed the precise distribution patterns of the ION branches in the upper lip. Furthermore, no detailed study has been available on this issue. This study aimed to reveal the precise distribution patterns of ION branches in the upper lip by dissecting the detached upper lip and cheek area using a stereomicroscope. MethodsDuring a gross anatomy course at Niigata University (2021–2022), nine human cadavers were examined with special focus on the relationship between ION branches in the upper lip and the layered structure of facial muscles. ResultsThe ION branched to the inferior palpebral (IP), external and internal nasal, and superior labial (lateral and medial) nerves. The ION branches in the upper lip did not run in a horizontal pattern from outside to inside but showed a predominantly vertical pattern. Considering their course, incising the upper lip mucosa transversely may cause paresthesia of the ION branches. The internal nasal (IN) and medial superior labial (SLm) branches tended to penetrate the orbicularis oris and descend between this muscle and labial glands, whereas the lateral superior labial (SLl) branches tended to innervate the skin. ConclusionsThese findings suggest that a lateral mucosal incision is recommended for oral vestibular incisions of the upper lip and that deeper incisions to the labial glands should be avoided when incising the medial side to preserve the ION during surgery from an anatomical point of view.

MINI REVIEW: REVISITING THE KIESSELBACH’S TRIANGLE

Epistaxis is spontaneous or induced bleeding of blood vessels in the nasal cavity. Sixty percent of people suffer from epistaxis in their lifetime occurring most in children and adults due to traumatic injuries and nasal cavity hemangiomas on the Kiesselbachs triangle. Kiesselbachs triangle/Little’s area is the inferior anterior quadrant part of the nasal septum just superior to the vestibule of nasal cavity. It’s formed by a network/vascular plexus of blood vessels that supply blood to the nasal septum and cavity. These vessels are braches of both internal carotid (anterior and posterior ethmoid arteries) and external carotid (spheno-palatine artery, greater palatine artery, superior labial artery) arterial systems. The mucosa lining epithelia over the plexus consists of proliferating to form columnar cells and mucus forming goblet cells. However this epithelium is too thin, Plexus forming blood vessels are large and the Plexus’ location at the nasal cavity’s subjects it to extremes of varying environmental conditions such as cold, heat, low and high moisture, eroding trauma putting it at high risk of epistaxis.

Sural communicating nerve for application as a vascularized nerve graft: A microneurovascular anatomic study in cadavers.

Sural nerve harvest causes paraesthesia to the lateral heel of the foot, which can debilitate those with already compromised proprioception. To circumvent this, we investigated an alternative donor nerve, branch of the lateral sural nerve complex called the sural communicating nerve (SCoNe), for its harvest and use as a vascularized nerve graft, in cadaver. The SCoNe was visualized by dissection in 15 legs from 8 human cadavers and the relationship of the SCoNe to the overall sural nerve complex was documented. The surface markings, dimensions, and the micro-neurovascular anatomy in the super-microsurgery range (up to 0.30 mm) of the SCoNe was recorded and analyzed. SCoNe graft surface marking was confined within a triangle drawn between the fibular head laterally, the popliteal vertical midline medially and the tip of the lateral malleolus inferiorly. The proximal end of the SCoNe was situated at a mean intersection distance of 5 cm from both the fibular head and popliteal midline respectively. The mean length of the SCoNe was 226 ± 43 mm with a mean proximal diameter of 0.82 mm and mean distal diameter of 0.93 mm. In 53% of the cadavers, an arterial input was present in the proximal third of the SCoNe and veins were predominantly (87%) present in the distal third. In 46% and 20% of the 15 legs respectively, there was a nutrient artery and vein perfusing the SCoNe in its central segment. The external mean diameter of this artery was 0.60 ± 0.30 mm, while the vein was slightly larger with a mean diameter of 0.90 ± 0.50 mm. SCoNe graft may preserve lateral heel sensation, compared to sural nerve harvest, pending clinical studies. It may have wide applications as a vascularized nerve graft, including being ideal as a vascularized cross-facial nerve graft because its nerve diameter is similar to the distal facial nerve branches. The accompanying artery is a good anastomotic match to the superior labial artery.

Anatomical study of divergences in facial artery endings.

Despite several studies focusing on the facial arteries variable courses, the findings have significantly differed. The divergent findings have made it increasingly challenging to establish consistent correlations. Thus, as a vital artery, the facial artery is prone to numerous variations, which makes the identification of the variations vital to clinical practice, particularly for the orofacial and rhinoplastic surgery, and the increasingly selective chemotherapy procedures. The present research uses angiography images for analysis in studying the bilateral facial artery variations noted in patients undergoing carotid angiography for the evaluation of congenital anomalies, cerebral vascular malformations, and intra-arterial procedures. Conventional angiography was used, as it is a vital assessment tool that helps in the assessment of variations in the facial arteries and is suitable in evaluating smaller vascular anatomy, due to the perfect spatial resolution and portrayal of vascular anatomy. Thus, rather than normal ending of the facial artery as an angular artery, the study disclosed that in certain instances, the artery termination took the form of a superior labial artery with a small lateral nasal artery branch located closer to the midline compared to the normal cases. Also, the study has disclosed a conspicuous pre-masseteric branch with small branches originating from the infraorbital artery and providing potential compensation for the facial artery's shortness. Regardless of the infrequency of such variations, it is vital that they are considered during the performance of any facial surgical procedure.

The versatility of the reverse superior labial artery flap

BackgroundThe reverse superior labial artery flap was introduced in 2015 as a reconstructive option for medial cheek defects. Notably, this flap can be redesigned as a more effective repair tool for large facial defect reconstruction. In this study, we redesigned the reverse superior labial artery flap to include the vascular territories of the infraorbital and transverse facial arteries in larger sizes for the repair of large facial defects. MethodsA reverse superior labial artery flap was used to repair large facial defects in 17 patients with a mean age of 74 years. The defects were located in the orbital region and entirely nasal sidewall in patient two, buccal region in patient three, and in lower lip and malar areas in patient five. The flap sizes ranged from 3.5 × 10 to 7 × 15 cm. A sensory examination was performed on the flaps at 6 and 12 months postoperatively. The mean follow-up period was 12 months. ResultsAll flaps survived without partial or total loss. In a small number of flaps minor complications such as venous congestion, epidermolysis, and dehiscence were seen. No functional disability was observed in the lower eyelid or lower lip, and the esthetic appearance was evaluated as satisfactory by the patients. In all the flaps, the protective sensation was recovered in the postoperative 12th month. ConclusionsThe reverse superior labial artery flap has an extensive arc of rotation, a reliable vascular pedicle, and a large cutaneous paddle. Therefore, this flap may be a versatile surgical repair tool for large cheek defects.

Buccal transposition flap for closure of maxillary lip defects in 5 dogs.

To describe the technique and outcomes of the closure of maxillary lip defects using a buccal transposition flap and to identify potential routes of vascular supply to the flap. Five dogs treated clinically and 1 cadaveric dog head. Short case series and cadaveric study. A left maxillary labial defect and a buccal transposition flap were created on a cadaver head. Iodinated contrast was injected into the left common carotid artery and computed tomography was performed to assess the vascular supply. Medical records were reviewed for all dogs that underwent tumor excision with maxillary lip resection, reconstructed with a buccal transposition flap. The buccal transposition flap was perfused by branches of the angularis oris artery and superior labial artery. Five dogs were included in this study. All flaps survived. Three dogs developed postoperative complications, including oronasal fistula (n=2) and partial flap dehiscence (n=1). The cosmetic and functional outcomes were considered satisfactory in all cases. Buccal transposition flaps for the closure of large maxillary lip defects provided adequate functional and cosmetic outcomes. The buccal transposition flap had vascular contributions from the angularis oris artery and the superior labial artery.

Lower Nose Arterial Plexus and Implications for Safe Filler Injections.

The lower nose has abundant blood supply; however, nasal tip necrosis still occurs following filler injections. This study revealed the complicated pattern of the arterial supply of the lower nose. The arterial pattern of the lower nose was studied in 40 cadavers using conventional dissections and translucent modified Sihler staining. Two arterial rings were connected in a figure of eight. The upper ring (nasal arterial circle) consisted of the lateral nasal and the subalar arteries encircling the nasal tip and alae. The lower ring (arterial plexus of the upper lip) was more important because of the contribution of the facial and superior labial arteries. This specific feature had not been mentioned elsewhere. Understanding this specific feature of the blood supply of the lower nose is essential for aesthetic physicians to perform the appropriate techniques during filler injection procedures in the nasal and perioral regions.

Superior labial artery and vein anastomosis configuration to be considered in lip augmentation

The treatment of cleft lip and palate is performed over a long period, starting immediately after birth. However, esthetic problems remain after lip augmentation. Endothelial cells of new capillaries are important for wound healing. Thus, the reconstruction of vascular networks is key to postoperative wound healing during lip augmentation. However, studies describing the superior labial artery (SLA) and superior labial vein (SLV) are rare, and their mutual positional relationship thus remains unclear. We procured 29 adult cadavers and ten fetuses. Macroscopic and histological examinations were performed on adult cadavers. We extracted soft tissues and blood vessels after micro-computed tomography (CT) and 3D tissue reconstruction. We performed histological investigations of vascular networks within the cleft lip in fetal samples. In adults, the SLV was distributed throughout the cutaneous side of the orbicularis oris muscle and the SLA, throughout the mucosal side. The SLV and SLA were separated by this muscle. Micro-CT images revealed that the SLA on the mucosal side transversed the orbicularis oris muscle to the SLV (55％). Histological analysis of fetuses revealed that the SLA was on the mucosal side, similar to that in adults, and traversed the orbicularis oris muscle in continuity with the SLV of the cutaneous side (100%). In lip augmentation, the reconstruction of the vascular structure, which involves the anastomosis of SLA and SLV passing through the orbicularis oris muscle, is an important factor when considering esthetic repair.

An unusual variation in the termination of facial artery in south Indian population: A human cadaveric case report

The facial artery is an important artery of the face, prone to many variations. Identification of these variations is of utmost importance in clinical practice, especially rhinoplastic and orofacial surgeries and also super selective chemotherapy procedures. In this case report, we report a bilateral facial artery variation encountered in a male cadaver during routine dissection. Instead of terminating as the angular artery, the facial artery terminated as the superior labial artery, giving the lateral nasal artery as a smaller branch, much closer to the midline than normal. A prominent pre-masseteric branch was noticed along with smaller branches from the infraorbital artery which offered possible compensation for the short facial artery. The case reported is a type II variation according to Bayram classification, and a type C variation as per Loukas classification. This variation is very rare and should be kept in mind while performing any surgical procedures of the face.

Revisiting the vascularity of the keratinized gingiva in the maxillary esthetic zone

BackgroundThe active arterial-to-arterial collaterals are a significant factor in the prevention of ischemia and extensive tissue necrosis in the case of arterial blockage of various tissues. The present study investigates the mucogingival vasculature in the maxillary esthetic zone mucosa in human cadavers and functionally evaluates the area, which is supplied by the terminal arterioles, on the individual level.MethodsIn the human cadaver study, macroscopic arterial analyses of the anterior maxillary vestibule in 7 specimens were scrutinized by latex milk injection. The tracks of the mucosal branches in relation to the mucogingival junction were investigated. In the functional study, individual gingival blood flow (GBF) changes were measured by laser speckle contrast imaging (LSCI) in 31 young subjects with healthy gingiva before and during 30-s compressions. This was conducted with a ball-shaped condenser. The data was analyzed by the linear mixed model.ResultsThe vertically aligned branches of the superior labial artery (SLA) divided into small, slightly deviating sub-branches near the mucogingival junction. These arteries created collateral plexuses and supplied the attached gingiva. The compression of these branches resulted in ischemia coronally with significant individual variation. The ischemia was either apico-mesial, apico-distal, or straight apical to the compression. A significant correlation was found between the ischemic area and the magnitude of the decrease in GBF (r = 0.81, p < 0.001). In males, 77% of the subjects, and 50% of the female subjects had an ischemic response in either region. The horizontal extension of the ischemic area ranged between 0.26 mm and 8.76 mm. Males had significantly higher baseline GBF and larger ischemia than females. At the base of the papilla, significant restoration of GBF was observed during compression in males, but not in females.ConclusionThe arcade anastomoses formed by the small arteries in the keratinized gingiva of the upper esthetic zone explain the consequences of vertical incisions. The considerable individual variations in ischemic responses might be the reason for unexpected surgical outcomes in some cases. Furthermore, there is increasing evidence that men have different vascular reactivity and/or regulation of collateral circulation than women, which may affect wound healing.

Use of facial vein graft with vascularized composite auricular helical rim flap for alar rim defects

Nasal alar defects lead to facial disfigurement, and nasal ala reconstruction is an important treatment option. The vascularized composite auricular flap based on the superficial temporal artery is an ideal option for a full-thickness nasal alar defect. However, the pedicle length and the discrepancy in artery diameter between the recipient vessel and flap pedicle continue to be major problems for free auricular composite tissue transfer. Considering that the angular artery is occasionally absent and the course of the infraorbital segment of the facial vein is constant, there are often no suitable vessels around the recipient site for anastomoses to the short pedicle of the flap. In the absence of a suitable recipient artery, an infraorbital segment of the facial vein measuring 2.5cm in length was taken as a graft for the anastomosis of the superficial temporal artery and superior labial artery. End-to-end anastomosis was performed easily. The flap was inset to reconstruct the contralateral ala. The facial vein graft for anastomosis of the superficial temporal artery and branch of the facial artery is a reliable and easy method to resolve the problem of a short pedicle and large artery discrepancy for nasal ala reconstruction with a vascularized composite helical rim flap.

True aneurysm of the superior labial artery

True aneurysm of the superior labial artery

Vascular survey of the maxillary vestibule and gingiva\u2014clinical impact on incision and flap design in periodontal and implant surgeries

ObjectivesCurrently, empirical clinical findings on the blood supply of the maxillary vestibule are not backed up with sufficient literature. The purpose of this study was to investigate the mucosal and periosteal vascular supply in the maxillary vestibule macroscopically and radiographically to improve surgical strategies and flap designs.Materials and methodsThirty head corpses were selected (9 dentate, 11 partially edentulous, 10 edentulous). Twenty-six corpses were injected by red latex milk and embalmed with Thiel solution. Four cadavers were prepared for corrosion casting. Arterial path and anastomoses in the maxillary vestibule of dentate, partially edentulous and edentulous ridges, were analyzed macroscopically and by computed tomography (CT).ResultsTransverse periosteomucosal anastomoses were detected in the posterior and esthetic zones of the maxillary vestibule. The buccal branches penetrated the interdental septum toward the palate. In the esthetic zone, superior labial artery (SLA) supplied the mucosa and the infraorbital artery (IOA) supplied the periosteum. Corrosion casting showed anastomoses between IOA and nasal septal branches. CT analysis revealed ipsilateral and contralateral anastomoses between SLA and IOA. In dentate ridges, mucosal star-shaped terminal branches were detected.ConclusionsThe macroscopic and radiographic vascular survey analysis revealed the anatomical background behind several clinically documented phenomena related to oral and periodontal surgeries.Clinical relevanceThis study permits clinicians to design less invasive flaps when releasing incisions in the maxillary vestibule during periodontal and implant surgeries. Our observations strongly point to the significance of an undamaged periosteum to prevent compromised flap revascularization and wound healing disturbances.

Anatomy of the Superior and Inferior Labial Arteries Revised: An Ultrasound Investigation and Implication for Lip Volumization.

Lips are considered a key element of facial attractiveness due to their central position in the face and their elemental role in verbal and nonverbal communication. The authors sought to provide clinically relevant information on the 3-dimensional pathway of the superior and inferior labial arteries within the lips to increase safety during labial soft tissue filler injections. The study enrolled 41 healthy volunteers with a mean age of 26.17 ± 9.6 years and a mean body mass index of 23.09 ± 2.3 kg/m2. Ultrasound imaging was performed at 6 different locations. The position of the labial arteries within the lips, depth of the arteries, cranio-caudal location of each artery in relation to the vermilion border, and diameter of the superior/inferior labial arteries were recorded. The most frequent location of both the superior and inferior labial arteries was the submucosal plane (58.5%) followed by intramuscular (36.2%) and subcutaneous (5.3%) planes. The depth of the superior labial artery in the upper lip was 5.6 ± 0.13 mm, whereas the depth of the inferior labial artery in the lower lip was 5.2 ± 0.14 mm. Both arteries were more frequently located within the red lip: upper lip (83% vs 18.7%) and lower lip (86.2% vs 13.8%). In the midline, the artery coursed within the red lip in all investigated volunteers. Clinically, results of this study favor a superficial injection plane for lip volumization procedures. A perpendicular approach to the lip (coming from the cutaneous lip) might increase safety because the artery is located most frequently within the red lip.