Three-Dimensional Location of the Facial Artery in Relation to the Nasolabial Fold in Asian People: A Cadaveric CTA Study.

BACKGROUND: Injection cosmetics have become popular in recent years. The nasolabial fold is one of the most important and dangerous regions in the midface, and its three-dimensional relationship with the facial artery remains unclear. METHODS: Fifty-two cadavers infused with lead oxide contrast medium via the external carotid arteries were scanned by computed tomography (CT). The three-dimensional model was reconstructed using Mimics and Origin software, and the relevant data were calculated using validated algorithms. RESULTS: There were three facial artery types according to its course in relation to the nasolabial fold. In the most common type, accounting for 83.7% of specimens, the facial artery evolves into an angular artery, with a horizontal distance between facial artery and nasolabial fold of - 1.90 ± 2.40, - 3.90 ± 2.95, - 5.18 ± 3.42, - 5.59 ± 3.53, - 5.59 ± 3.83, - 6.07 ± 4.10, - 6.92 ± 3.70, - 6.79 ± 3.37, - 4.52 ± 3.20, and - 2.76 ± 3.60 (mm) from the nasal ala to the oral commissure and a vertical distance of - 4.03 ± 2.56, - 3.27 ± 2.27, - 2.81 ± 2.57, - 2.1 ± 2.64, - 1.5 ± 3.32, - 0.71 ± 3.99, 0.92 ± 4.43, 0.4 ± 5.31, - 4.14 ± 5.14, - 7.05 ± 4.74 (mm). CONCLUSIONS: The facial artery is vulnerable to damage when injecting filler in the nasolabial fold. For the upper 1/3 of the nasolabial fold, the supraperiosteal layer is recommended for injection, while for the lower 2/3 of the nasolabial fold, the dermal layer along the nasolabial fold is recommended. LEVEL OF EVIDENCE IV: 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 .

Anatomical Study of the Superior Auricular Artery Using 3-Dimensional Computed Tomography Angiography.

BACKGROUND: The superior auricular artery (SAA)-retroauricular flap is commonly used for the repair of defects of the superior auricle. There are few studies about the anatomy of the SAA. OBJECTIVE: This study mainly analyzed the anatomical pattern of SAA. MATERIALS AND METHODS: Computed tomography (CT) was performed on 26 cadaver heads infused with lead oxide. The anatomical pattern of the SAA was statistically analyzed by 3-dimensional CT images. RESULTS: The SAA was classified into 3 types according to whether it gave off the helix branch or the auricular dorsal branch. The SAA was located mainly in an area 2 cm above and below the horizontal line at the midpoint of the 2 base points (the otobasion superius and the apex of the external auditory canal). The origin of each branch of the SAA was mainly located in Areas 2, 3, and 4 within a circular area that had the otobasion superius as the center of the circle and a radius of 2 cm. CONCLUSION: In this study, the 3 anatomical types and anatomical patterns of the SAA were identified. These findings can provide a reference for the design of SAA-retroauricular flaps and for surgical planning.

The Auricular Injection Technique: A New Treatment for Lying Ear.

SUMMARY: Lying-ear deformity refers to an auricle that bends backward excessively, is excessively folded against the head, and has a very prominent antihelix. It usually requires experienced surgeons to perform surgical treatment and a prolonged postoperative recovery process. This article proposes a simple and effective hyaluronic acid injection technique that significantly improves the shape of the outer ear and enhances perceived facial aesthetics. Twenty patients underwent treatment with multiple injections. Measure-related parameters were used to evaluate the postoperative effect, and the results were graded using a visual analog scale. Interrater reliability among graders was evaluated using intraclass correlation coefficients. After treatment, no serious complications, such as infection or embolism, occurred. Six months after the procedure, the average auriculocephalic angle increased from 25.11 ± 9.46 to 32.72 ± 8.29 degrees, the average conchoscaphal angle increased from 87.69 ± 9.06 to 95.94 ± 7.11 degrees, and patients' average visual analog scale score increased from 4.40 ± 1.14 to 8.57 ± 0.68. Interrater reliability was fair to good for visual analog scale before injection and 6 months after injection (intraclass correlation coefficients, 0.49 and 0.45, respectively; both P < 0.001). The patients were satisfied with the injection process and results. This injection protocol improved the shape of the outer ear, resulting in excellent postoperative outcomes.

Deep Temporal Artery Anatomy: Implications for Improving the Safety of Deep Temporal Injections.

BACKGROUND: Knowledge of the anatomy of the deep temporal artery (DTA) is critical to ensure safe filling of the deep temporal region. However, current treatment guidelines still focus on how to avoid the superficial temporal artery and the middle temporal vein, and an understanding of the safety of avoiding DTA injury is lacking. OBJECTIVE: The purpose of this study was to determine the positioning and course of the DTA to help clinicians safely perform the injection and filling in the temporal region. METHODS: Computed tomography (CT) scans and dissections of the skulls of 34 fresh frozen cadavers perfused with lead oxide were performed. Reconstruction and trajectory analysis of all DTA branches were performed using Mimics and MATLAB software. RESULTS: In this study, the DTA was identified in all samples, which originated from the maxillary artery of the external carotid artery system. According to image reconstruction and anatomical observations, the distribution of the anterior and posterior branches of the DTA had two different distribution patterns. The anatomical level of the DTA is located between the temporal muscle and the periosteal layer. Compared with observations in previous studies, the anterior branch of the DTA is slightly different, and we found that its course is closer to the frontal area in Asian specimens. CONCLUSION: The anatomical information on the DTA described in this study may help improve awareness of the safety of temporal injection by aesthetic physicians. LEVEL OF EVIDENCE IV: 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 Table of Contents or online Instructions to Authors www.springer.com/00266. .

New Insight into Glabellar Arteries: A Three-Dimensional Computed Tomography and Dissection Study.

BACKGROUND: Vascular complications from glabellar intravascular filler injections are major safety concerns. Filler injection into the glabella without precise knowledge of its vascular topography poses a risk of severe complications. METHODS: Computed tomography was used to study 90 cadaveric heads after contrast agent and filler injection, and 15 cadaveric heads were dissected. RESULTS: Central (CAs), paracentral (PCAs), and reverse dorsal nasal arteries (rDNAs) were found in 70 (38.9%), 58 (32.2%), and 16 (8.9%) of the 180 hemifaces, respectively. Based on the presence of CAs, PCAs, and rDNAs between the bilateral supratrochlear arteries (STAs), glabellar arteries were categorized into two main patterns: in type 1 [without named arteries between bilateral STAs; 22 of 90 (24.4%)], the glabella was supplied by bilateral STAs and their branches; in type 2 [with named arteries between bilateral STAs; 68 of 90 (75.6%)], the glabella was supplied by bilateral STAs and CAs, PCAs, and rDNAs. Type 2 could be further divided into three subtypes: in type 2a [45 of 90 (50.0%)], the glabella was supplied by bilateral STAs and one of the named arteries; in type 2b [21 of 90 (23.3%)], the glabella was supplied by bilateral STAs and two of the named arteries; and in type 2c [two of 90 (2.3%)], the glabella was supplied by bilateral STAs and unilateral CA, PCA, and rDNA. CONCLUSION: This study elucidated novel arterial systems and proposed considerations for glabellar filler injection.

Aesthetic Concerns of Chin Augmentation With Hyaluronic Acid Soft Tissue Filler in Chinese: A Prospective, Observational Study.

BACKGROUND: The chin is an important facial structure that directly affects the overall contour of the face. The key to achieving a beautiful, effective, and safe chin injection is to make a good facial assessment and use an appropriate injection technique to achieve the best injection effect. OBJECTIVE: In this article, the authors will discuss cosmetic concepts for the chin area and verify the effectiveness of chin augmentation techniques. MATERIALS AND METHODS: Chin volume injections were performed on 23 Asian female subjects and 15 Asian male subjects. Demographic and imaging data were collected, and the facial aesthetic length was calculated. The authors also measured the length of beautiful chins, as evaluated by 2 plastic surgeons, and the ratios of chins from "The 100 Most Beautiful/Handsome Faces in China" published by TCC Asia in 2020. RESULTS: The mean volume of chin filling was 1.89 ± 0.74 mL in female subjects and 2.68 ± 1.28 mL in male subjects. The ideal length of the chin was equal to that of the nasal dorsum in male subjects, and the ideal chin-to-nasal dorsum ratio was 0.9 in female subjects. CONCLUSION: In this study, the authors investigate sex differences in chin aesthetics among the Chinese population and introduce an aesthetic and anatomical approach to chin injection.

Clinical Anatomy of the Chin Evaluated by 3-Dimensional Tomography and Cadaveric Dissection: Implications for Safety and Optimal Injection Techniques in Chinese.

BACKGROUND: Soft tissue fillers have been widely used for the correction of chin volume loss because of congenital conditions and aging. OBJECTIVE: This study aimed to discuss anatomical concerns for chin filler injections, which may help to reduce the incidence of severe intravascular embolization complications and improve patient satisfaction. METHODS AND MATERIALS: We scanned 40 cadaveric heads with a contrast agent using a 64-row spiral computed tomography scanner. The scan was visualized by a Philips IntelliSpace workstation and analyzed by Materialise's interactive m image control system software to measure and quantify the arterial data. Twenty of 40 cadavers were dissected to define the layers of tissue. RESULTS: In total, 221 arteries passed through the sagittal plane of 40 specimens. The number of superficial arteries (163 of 221) was much greater than the number of deep arteries (58 of 221). The number of arteries gradually decreased with distance from the lower lip vermilion border plane, which formed the lower third of the face. CONCLUSION: This study introduces a safe and effective technique for administering chin filler injections that minimizes risks and improves patient satisfaction.

Zygomatico-Orbital Artery: A Reevaluation of the Temporal Blood Vessels.

BACKGROUND: The current anatomical description of the zygomatico-orbital artery (ZOA) is mainly based on cadaver head studies and does not accurately reflect the complete anatomical information of the ZOA. The purpose of this study was to reveal the anatomical characteristics of the ZOA and to provide an anatomical basis for relevant operations in the temporal area. METHODS: Computed tomographic scans and autopsies were performed on 78 cadaver heads perfused with lead oxide. Mimics software was used to construct a three-dimensional image based on the bilateral intertragic notches and the right inferior orbital margin for a detailed analysis of the ZOA. RESULTS: The occurrence rate of ZOA in the 101 qualified hemisectioned cadaver heads was 86.14% (87 of 101). According to our observations, 46 of 87 (52.87%) originated from the superficial temporal artery above the zygomatic arch, 23 of 87 (26.44%) from the superficial temporal artery under the zygomatic arch, and 18 of 87 (20.69%) from the frontal branch of the superficial temporal artery. The ZOA communicates with the deep and superficial arches of the supraorbital artery, transverse facial artery, and ophthalmic artery. CONCLUSIONS: This study describes the anatomical characteristics of the ZOA. Moreover, these findings may guide skin flap transplantation and prevent associated injection complications.

Positions of the Glabellar Arteries: Implications for Glabellar Injection.

BACKGROUND: Glabellar filler injection is linked to an increased risk of blindness. A thorough understanding of vascular changes in the glabellar area is critical for safety. The study's goal was to precisely determine the three-dimensional placements of the arteries in the glabellar area. METHODS: In 117 cadavers, the vascular structures in the glabellar area were examined. There were four segments (S1/S1'-S4/S4') and five points (P1-P5) specified. The number of identified arteries found in each section and at each position was tallied. Additionally, the depth of the underlying identified artery under each site was measured. RESULTS: One to three named arteries per glabellar segment were found. Each segment had at least one named artery, and the number of named arteries detected between S1/S1' and S4/S4' decreased. The chance of encountering identified arteries at the 5 designated locations, P1-P5, was 7/117 (6.0%), 6/117 (5.1%), 7/117 (6.0%), 6/117 (5.1%), and 16/117 (13.7%), respectively. At P1-P5, the major artery trunk was 1.8 ± 0.3 mm, 1.6 ± 0.3 mm, 1.4 ± 0.2 mm, 1.3 ± 0.3 mm, and 1.1 ± 0.2 mm below the skin. CONCLUSIONS: The site of the glabellar arteries was clearly shown in this investigation; these arteries were met at a rate of 14% from P1 to P5. We demonstrated that a single entry site through the glabella via cannula could readily keep the needle deep enough for safe glabellar filler injection. LEVEL OF EVIDENCE V: 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 .

Anatomical Basis for Malar Augmentation Injection With the Zygomatic Ligamentous System.

BACKGROUND: The malar augmentation injection has gained popularity in recent years, but the exact location of each injection site has not been clearly identified. OBJECTIVE: To discover ideal injection sites by comprehensively considering the distributions of ligaments, muscles, and vessels. MATERIALS AND METHODS: Eighteen cadaver heads were dissected to investigate the zygomatic ligamentous system and to measure the position of muscles. Sixty-six cadaver heads were subjected to computed tomographic scanning and three-dimensional vessel reconstruction. Radiological evaluation of the fillers was performed before and after experimental injection in one hemiface and dissected to confirm safe delivery. Five patients were enrolled in a prospective clinical study. 2D and 3D photographs were taken before and after the injections for comparison. RESULTS: Site 1 was defined along the zygomatic arch, except the first 1/4 length and the midline of the arch. Site 2 was on the body of the zygoma, superior to the level of the infraorbital foramen and medial to the jugale. Site 3 was defined in the anteromedial midface approximately 30 mm below the lateral canthus. CONCLUSION: Injections at these 3 sites can be performed within the range of the ligaments to achieve effective lifting effects and minimize potential complications.

Vasculature of the Nasal Cartilage Region Related to Filler Injection.

BACKGROUND: A filler injection in the nose can be essential but is also dangerous, especially in the nasal cartilage region. To safely and accurately perform a filler injection, surgeons must have detailed knowledge of nasal anatomy. OBJECTIVES: Associated the vessel branches and the characteristics of different nasal regions to provide suggestions for more suitable injection sites. METHODS: Fifty specimens underwent computed tomography (CT) after contrast infusion. Qualified specimens were selected for 3D CT reconstruction. Dissection was performed to confirm the accuracy of the CT data. RESULTS: The branches of arteries with large diameters, the dorsal nasal artery (DNA) and the lateral nasal artery (LNA) were distributed within the superficial musculoaponeurotic system layer. The DNA was seen in only 58% of specimens. The artery crossed the midline over the upper lateral cartilage in 16% of specimens. The LNA was a constant branch that traversed the nasal tip. The LNA crossed the midline to the contralateral side in 18% of patients. We divided the nasal cartilage dorsum into two regions for easy handling: the supratip region (STR) and the nasal tip region (NTR). The branches distributed in the STR mostly originated from the DNA (81.6%, 40/49), while those in the NTR mostly originated from the LNA. CONCLUSIONS: The vasculature of the nasal cartilage region observed in this study is similar to that observed in previous studies. However, we found that the STR was an advantageous area for filler injection. At the same time, we provided suggestions for more suitable injection methods. LEVEL OF EVIDENCE IV: 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 .

Clarifying the Anatomy of the Zygomatic Cutaneous Ligament: Its Application in Midface Rejuvenation.

BACKGROUND: Anatomical knowledge of the zygomatic cutaneous ligament is crucial for rejuvenation of the anteromedial midface. However, there is a lack of satisfactory descriptions of the anatomy of the zygomatic cutaneous ligament, and the exact range and location are still controversial. The present study attempts to clarify the anatomy of the zygomatic cutaneous ligament to provide vital information for clinical operations. METHODS: Facial dissection was performed on 36 cadaver hemifaces. The location of the zygomatic cutaneous ligament was investigated and recorded relative to the Frankfort horizontal line and several vertical reference lines. The relative relationship of the zygomatic cutaneous ligament with surrounding anatomical structures was also investigated. RESULTS: The zygomatic cutaneous ligament is a septum-like osteocutaneous ligament originating from the periosteum of the maxilla and zygoma. The overall range of the zygomatic cutaneous ligament starts at the origin of the levator labii superioris and then extends laterally, following the curvature of the inferior bone margin. After merging with the ligamentous part at the origin of zygomaticus minor and zygomaticus major muscle (11.65 mm inferior to the horizontal line), it continues as the zygomatic retaining ligament on the zygomatic arch. The vertical distances between the zygomatic cutaneous ligament and horizontal line along the L1, L2, L3, L4, and L5 reference lines are 9.1, 19.5, 22.1, 21.7, and 18.7 mm, respectively. CONCLUSION: The anatomical data obtained in the present study regarding the location of the zygomatic cutaneous ligament might be valuable for understanding the appearance of the midcheek fold and be helpful for surgical procedures to rejuvenate the anteromedial midface.

Three-Dimensional Computed Tomographic Study of the Supratrochlear Artery and Supraorbital Artery to Determine Arterial Variations and Their Relationship.

BACKGROUND: The forehead has high risks associated with filler injection considering its highly complex vascular system. This study aims to thoroughly describe the anatomical variations and relationships between the supratrochlear artery (STA) and supraorbital artery (SOA). MATERIALS AND METHODS: We studied 56 cadaveric heads by computed tomography after contrast-agent injection. RESULTS: The deep branch of the STA originated in the deep superior orbital arcade and the ophthalmic artery (OA), whereas that of the SOA originated at 3 locations: the deep superior orbital arcade, deep superior orbital artery, and OA. The superficial branch of the STA also had 3 origins: the superficial superior orbital arcade, OA, and angular artery, whereas the superficial branch of the SOA had 2 origins: the superficial superior orbital arcade and OA. Based on the relationship between the STA and SOA, 2 main arterial distribution patterns were observed in both superficial and deep layer arteries: STA/SOA connected pattern and STA/SOA disconnected pattern, of which the latter pattern has 3 subtypes. CONCLUSION: The forehead arteries have complex origins. The relationship of the supratrochlear and supraorbital arteries could be categorized into 2 main patterns. The study elucidated the complexity of the forehead vasculature.

Three-Dimensional Computed Tomography of the Detoured Facial Artery: Variations and Implications for Nasojugal Groove Correction.

BACKGROUND: When performing filler injection procedures to the nasojugal groove, there is the risk of iatrogenic damage to the detoured facial artery. OBJECTIVE: To determine the 3-dimensional location of the detoured facial artery. MATERIALS AND METHODS: The branches of the facial arteries from 118 cadaveric hemifaces were scanned using computed tomography and reconstructed using the Mimics software program. RESULTS: Detoured facial arteries were found in 47 of the 118 hemifaces (39.8%). Two main arterial patterns were identified: in Type I (29 of 47 cases), there were both detoured and nasolabial trunks where the facial artery originated, whereas in Type II (18 of 47 cases), there was only a detoured trunk. The detoured trunk originated 32.0 ± 5.3 mm from the midsagittal line, 5.0 ± 2.8 mm from the occlusion plane, and 5.9 ± 3.5 mm below the skin layer; the inflection of the detoured trunk was located 30.0 ± 5.6 mm laterally, 26.2 ± 4.4 mm superiorly, and 5.7 ± 2.6 mm deep. The meeting point with the inferior orbital rim plane was located 17.1 ± 3.4 mm laterally, 43.4 ± 3.1 mm superiorly, and 2.8 ± 1.7 mm deep. CONCLUSION: The 3-dimensional location of the detoured facial artery as reported here will help clinicians to avoid iatrogenic damage when they are performing filler injection procedures.

Three-Dimensional Computed Tomography Scanning of Temporal Vessels to Assess the Safety of Filler Injections.

BACKGROUND: Temple filler injection is one of the most common minimally invasive cosmetic procedures involving the face; however, vascular complications are not uncommon. OBJECTIVES: This study aimed to investigate the anatomy of the temporal vessels and provide a more accurate protocol for temple filler injection. METHODS: Computed tomography (CT) scans of 56 cadaveric heads injected with lead oxide were obtained. We then used Mimics software to construct 3-dimensional (3D) images of the temporal vessels described by a coordinate system based on the bilateral tragus and right lateral canthus. RESULTS: In the XOY plane, the superficial temporal artery (STA), middle temporal artery (MTA), zygomatico-orbital artery (ZOA), posterior branch of the deep temporal artery (PDTA), and lateral margin of the orbital rim divide the temple into 4 parts (A, B, C, and D). The probabilities of the STA, MTA, ZOA, and PDTA appearing in parts A, B, C, and D were 30.73%, 37.06%, 39.48%, and 77.18%, respectively. In 3D images, these vessels together compose an arterial network that is anastomosed with other vessels, such as the external carotid, facial, and ocular arteries. CONCLUSIONS: 3D CT images can digitally elucidate the exact positions of temporal vessels in a coordinate system, improving the safety of temple filler injections in a clinical setting.

Deployment of the Ophthalmic and Facial Angiosomes in the Upper Nose Overlaying the Nasal Bones.

BACKGROUND: Nasal filler placement is associated with a high risk of blindness. The arterial supply to the upper nose overlaying the nasal bones is poorly understood. OBJECTIVES: The aim of this study was to visualize and analyze the deployment of the ophthalmic and facial angiosomes in the upper nose to help prevent blindness following nasal filler injections. METHODS: The arterial systems of 62 cadaveric heads were filled with lead oxide contrast agent, and computed tomography (CT) images were acquired and reconstructed in 3 dimensions. RESULTS: Twenty-six of the cadaveric noses examined demonstrated clear CT images of the facial and ophthalmic angiosomes in the upper nose. The Type 1 upper nose (15.4%) is supplied by 2 independent ophthalmic angiosomes that communicate indirectly through a choke anastomosis. The Type 2 upper nose (38.5%) is supplied by 2 ophthalmic angiosomes with a true anastomosis between them. The Type 3 upper nose (46.1%) is supplied by both ophthalmic and facial angiosomes with true anastomoses across the dorsal midline. These true anastomoses are mediated by the radix arcade in 46% of the noses and involve the dorsal nasal artery in 65% of the cases. The anastomoses all cross the upper dorsal midline and are directly linked to the ophthalmic angiosome. CONCLUSIONS: The deployment and anastomosis of the facial and ophthalmic angiosomes in the upper nose fall into 3 major patterns. About 85% of the noses have true anastomotic arteries that cross the upper dorsal midline and are directly linked to the ophthalmic circulation. Dorsum filler injection poses a significant risk of blindness.

Injectable Filler Technique for Face Lifting Based on Dissection of True Facial Ligaments.

BACKGROUND: Strengthening weakened ligament tissues with injectable fillers to improve their supportive effect may achieve the aesthetic goal of face lifting. OBJECTIVES: The aim of the study was to design an injectable technique for enhancing the true facial ligaments and dissect the ligaments to provide anatomical guidance for effective injection. METHODS: Six true facial ligaments were chosen as target anatomical sites for injection. Specimens were dissected, and 3-dimensional (3D) images were reconstructed to confirm the exact location of each injection site and to confirm that the proposed injection routes will not cause dangerous vascular damage. A total of 5 patients received the injections; 3D images were taken before and after the injections for comparison and clinical outcome assessments. RESULTS: The injection technique was designed to target 6 true facial ligaments, as follows. Site 1 targeted the temporal ligamentous adhesion region to lift the lateral ends of the eyebrows. Site 2 targeted the region of the lateral orbital thickening to lift the lateral canthus. Site 3 and site 4 targeted the zygomatic retaining ligaments and zygomatic cutaneous ligaments, respectively, to augment the soft tissues of the midface. Site 5 targeted the region of the maxillary ligament to lessen the nasolabial folds, and site 6 targeted the mandibular ligament to reduce the marionette line. CONCLUSIONS: This site-specific injection technique targeting the true ligaments may lead to increased efficiency and accuracy of face rejuvenation and exert a lifting effect.

Three-Dimensional Computed Tomographic Study on the Vessels of the Zygomatic Region: Arterial Variations and Clinical Relevance.

BACKGROUND: Injection-based techniques for "cheek augmentation" have gained popularity in recent years. The aim of this study was to perform a topographic analysis of the depth and distribution of the vessels in the zygomatic region to facilitate clinical procedures. METHODS: The external carotid arteries of seven cadaveric heads were infused with lead oxide contrast medium. The facial and superficial temporal arteries of another 12 cadaveric heads were injected sequentially with the same medium. Computed tomographic scanning was then performed, and three-dimensional computed tomographic scans were reconstructed using validated algorithms. RESULTS: The vessels on the zygomatic arch received a double blood supply from across the upper and lower borders of the arch, and the number of the vessels varied from one to four. Ninety percent of the vessels on the zygomatic arch were at a depth of 1 to 2.5 mm, and 75 percent were at a depth of 10 to 30 percent of the soft-tissue thickness. The vessels were concentrated on the midline of the zygomatic arch and the lateral margin of the frontal process. All samples showed a vessel travel along the lateral margin of the frontal process that eventually merged into the superior marginal arcades. CONCLUSIONS: This study reported a topographic analysis of the depth and distribution of the vessels in the zygomatic region based on three-dimensional scanning. The results indicated that injection on the zygomatic arch should be performed deep to the bone, and the vascular zones anterior or posterior to the midline of the zygomatic arch were relatively safe injection areas.