Jae-Gi Lee

New Anatomical Insights on the Course and Branching Patterns of the Facial Artery: Clinical Implications of Injectable Treatments to the Nasolabial Fold and Nasojugal Groove

Background: Improper manipulation of injectable treatments to the face can result in disastrous vascular complications. The aim of the present study was to elucidate the detoured course of the facial artery and to provide detailed metric data regarding facial artery location with a view to helping physicians avoid iatrogenic vascular accidents during injectable treatments. Methods: Sixty specimens from 35 embalmed cadavers (24 male and 11 female cadavers; mean age, 70.0 years) and one fresh male cadaver (age, 62 years) were used for this study. Results: In 56 cases (93.3 percent), the branches of the facial artery were observed at the vicinity of the nasolabial fold. The facial artery was located 3.2 ± 4.5 mm (mean ± SD) lateral to the ala of the nose and 13.5 ± 5.4 mm lateral to the oral commissure. It crossed the nasolabial fold in 33.9 percent of cases, and ascended within 5 mm of the nasolabial fold in 42.9 percent. The facial artery and detoured branches were found in 18 cases (30.0 percent). In the cases with detoured branches, the facial artery turned medially over the infraorbital area at 39.2 ± 5.8 mm lateral to the facial midsagittal line and 35.2 ± 8.2 mm inferior to the plane connecting the medial epicanthi of both sides. The nasojugal portion of the detoured branch traveled along the inferior border of the orbicularis oculi and then ascended toward the forehead, forming the angular artery. Conclusion: This detailed vascular anatomy of the facial artery will promote safe clinical manipulations during injectable treatments to the nasolabial fold and nasojugal groove.

Facial arterial depth and relationship with the facial musculature layer.

Background: Previous studies have revealed a variation in the origin and distribution patterns of the facial artery. However, the relationship between the facial artery and the facial muscles has not been well described. The purpose of this study was to determine the facial artery depth and relationship with the facial musculature layer, which represents critical information for dermal filler injection and oral and maxillofacial surgery. Methods: Fifty-four embalmed adult faces from Korean cadavers (36 male and 18 female cadavers; mean age, 73.3 years) were used in this study. A detailed dissection was performed, with great care being taken to avoid damaging the facial artery underlying the facial skin and muscle. Results: The facial artery was first categorized according to the patterns of its final arterial branches. The branching pattern was classified simply into three types: type I, nasolabial pattern (51.8 percent); type II, nasolabial pattern with an infraorbital trunk (29.6 percent); and type III, forehead pattern (18.6 percent). Each type was further subdivided according to the facial artery depth and relationship with the facial musculature layer as types Ia (37.0 percent), Ib (14.8 percent), IIa (16.7 percent), IIb (12.9 percent), IIIa (16.7 percent), and IIIb (1.9 percent). Conclusion: This study provides new anatomical insight into the relationships between the facial artery branches and the facial muscles, including providing useful information for clinical applications in the fields of oral and maxillofacial surgery.

The risorius muscle: anatomic considerations with reference to botulinum neurotoxin injection for masseteric hypertrophy.

BACKGROUND The botulinum neurotoxin Type A (BTX) injection into the masseter muscle often causes a change in the facial expression. There is as yet no precise anatomic evidence to support this etiologic factor of constrained facial expressions. OBJECTIVE The aim of this study was to clarify the location and boundaries of the risorius muscle and its topographical relationship with the surrounding structures. MATERIALS AND METHODS This study involved the dissection of 48 hemifaces. The locations of origin and insertion points of the risorius muscle were measured, and the masseter muscle was divided into 6 equally sized rectangular areas. RESULTS Cases where the masseter muscle was covered by the risorius muscle were classified into the following 4 types: in Type A, Area III was partially covered by the risorius (17.8%); in Type B, Area VI was partially covered (20.0%); in Type C, Areas III and VI were partially covered (53.3%); and in Type D, Areas II, III, and VI were covered (6.7%). CONCLUSION These findings suggest that the medial part of the masseter muscle represents a hazard zone into which the injection of BTX may affect the risorius muscle, potentially resulting in iatrogenic unnatural facial expressions.

Realization of Masticatory Movement by 3-dimensional Simulation of the Temporomandibular Joint and the Masticatory Muscles

AbstractMasticatory muscles are closely involved in mastication, pronunciation, and swallowing, and it is therefore important to study the specific functions and dynamics of the mandibular and masticatory muscles. However, the shortness of muscle fibers and the diversity of movement directions make it difficult to study and simplify the dynamics of mastication. The purpose of this study was to use 3-dimensional (3D) simulation to observe the functions and movements of each of the masticatory muscles and the mandible while chewing. To simulate the masticatory movement, computed tomographic images were taken from a single Korean volunteer (30-year-old man), and skull image data were reconstructed in 3D (Mimics; Materialise, Leuven, Belgium). The 3D-reconstructed masticatory muscles were then attached to the 3D skull model. The masticatory movements were animated using Maya (Autodesk, San Rafael, CA) based on the mandibular motion path. During unilateral chewing, the mandible was found to move laterally toward the functional side by contracting the contralateral lateral pterygoid and ipsilateral temporalis muscles. During the initial mouth opening, only hinge movement was observed at the temporomandibular joint. During this period, the entire mandible rotated approximately 13 degrees toward the bicondylar horizontal plane. Continued movement of the mandible to full mouth opening occurred simultaneously with sliding and hinge movements, and the mandible rotated approximately 17 degrees toward the center of the mandibular ramus. The described approach can yield data for use in face animation and other simulation systems and for elucidating the functional components related to contraction and relaxation of muscles during mastication.

Sihler-stain study of buccal nerve distribution and its clinical implications

OBJECTIVE The aim of this study was to elucidate the precise distribution of the buccal nerve (BN) and its anatomic relationship with the infraorbital nerve (ION) and mental nerve (MN). STUDY DESIGN Eight human specimens were subjected to Sihler staining, which is a highly accurate method for visualizing the distribution of nerve fibers without alteration of the nerve. RESULTS It was found that the BN mainly proceeded medially from its point of entrance near the parotid duct opening to the angular area of mouth, giving off tiny branches along its trajectory. Some of these branches were distributed in upper angular area, over the cheilion, intermingling with branches of the ION. Intermingling of the BN and the MN was also observed in the premolar area of the lower lip. CONCLUSIONS This new information regarding the distribution of BN should be taken into consideration when evaluating the possible effects of BN damage.

Description of a novel anatomic venous structure in the nasoglabellar area.

AbstractInjectable dermal fillers are frequently used to reduce the appearance of various facial creases and rhytids. However, venous complications can develop while injecting dermal filler, especially in the nasoglabellar area. The aims of this study were to determine the anatomic patterns of the veins in the nasoglabellar area and to elucidate their detailed location with reference to various facial landmarks. Forty-one heads from Korean and Thai cadavers were dissected. When the anastomosing vein between the bilateral angular veins (AVs) was located in the nasoglabellar area, it was designated the intercanthal vein (ICV). The bilateral AVs continued as the facial vein without any communicating branches in 12 cases (29.3%). At the radix of the nose, the AV communicated with the ICV, connecting them bilaterally. The ICV was found above (type IIA) and below (type IIB) the intercanthal line in 26 (63.4%) and 3 (7.3%) cases, respectively. The ICV can be regarded as a candidate causative site for the frequent complications associated with dermal filler injection in the nasoglabellar area, and utmost care should be taken when injecting in this area, such as when performing radix augmentation and softening wrinkles in the glabellar area.

Medial muscular band of the orbicularis oculi muscle.

Abstract Despite the importance of anatomic variations in the muscular bands around the orbicularis oculi muscle (OOc), little is known about them. The morphology and variations therein of the medial muscular band of the OOc were thus examined in the current study. Sixty-one hemifaces of Korean cadavers were dissected to enable examination of the anatomic organization of the muscles around the OOc. A medial muscular band of the OOc was observed in 40 cases (65.6%). Three patterns of attachment were found. In type A (14 cases, 23%), it attached to the frontal belly without being attached to the medial canthal tendon; in type B (14 cases, 23%), it originated from the medial canthal tendon at the lower portion of the OOc and inserted into the cheek skin, and in type C (12 cases, 19.7%), it was also observed to insert into the cheek skin and attach to the frontal belly without being attached to the medial canthal tendon. The distance between the inferior edge of the OOc and the subnasale was 16.3 (SD, 4.3) mm and 14.5 (SD, 4.4) mm in cases with and without a medial muscular band, respectively. A space was observed on the inferolateral side of the OOc in about 67.2% of cases. These findings regarding the medial muscular band of the OOc increase further the anatomic variations associated with this region. In addition, it appears that this medial muscular band of the OOc can help to prevent drooping of the OOc.

Intramuscular communicating branches in the flexor digitorum profundus: dissection and Sihler's staining.

PurposeThis study was designed to clarify the anatomy of the intramuscular communicating branch (ICb) between the median and ulnar nerves in the flexor digitorum profundus (FDP), and morphologically demonstrate the location of connection.MethodsTwenty Korean cadavers were dissected and a further 8 were subjected to modified Sihler’s staining to investigate the pattern of innervation of the ICb and the location of its communicating points in muscle.ResultsThe median and ulnar nerves divided into small branches before entering FDP muscle. Of these small branches, one or two met inside the muscle. This communicating pattern could be classified into three types: type I, communicating branches in both the proximal and distal regions; type II, at least one communicating branch in the proximal region; type III, at least one communicating branch in the distal region. Of 20 dissected specimens, no case of type I was observed, but 3 cases of type II and 15 cases of type III were found. No ICbs at all were found in two of the dissected specimens. In eight stained specimens, one was classified as type I, two as type II, and five as type III. The proximal communicating branches were located at 34.1% from the interepicondylar line, inside the third muscle bundle. The distal communicating branches were located at 66.0% from the interepicondylar line, between third and fourth muscle bundles.ConclusionsThese findings could provide critical anatomical information regarding the nerve distribution of FDP focused on the ICbs.

Morphometric analysis of the anterior region of the maxillary bone for immediate implant placement using micro-CT.

The purpose of this study was to elucidate the relationship between the maxillary incisor roots and surrounding alveolar structures using microscopic computerized tomography (micro‐CT) for the immediate implant placement. Nineteen maxillae from 14 Korean cadavers were used in this study. All specimens were scanned and reconstructed into a three‐dimensional (3D) structure using a micro‐CT system. The roots of the maxillary central and lateral incisors became dramatically narrower from 6 mm above the cementoenamel junctions to the apex. The roots of the maxillary incisors and canine were located at the labial one fifths region of the alveolar bone. The angle formed by the longitudinal root axis and the alveolar bone was greatest at the maxillary canine. On the basis of the results of this study, guidelines for immediate implant placement can be suggested on the implant diameter and drilling angle to minimize damage of the alveolar plate. Clin. Anat. 24:462–468, 2011.

Characterizing the Lateral Border of the Frontalis for Safe and Effective Injection of Botulinum Toxin.

BACKGROUND The forehead is a common site for injection of botulinum neurotoxin type A (BoNT-A) to treat hyperactive facial muscles. Unexpected side effects of BoNT-A injection may occur because the anatomy of the forehead musculature is not fully characterized. OBJECTIVES The authors described the lateral border of the frontalis in terms of facial landmarks and reference lines to determine the safest and most effective forehead injection sites for BoNT-A. METHODS The hemifaces of 49 embalmed adult Korean cadavers were dissected in a morphometric analysis of the frontalis. L2 was defined in terms of FT (the most protruding point of the frontotemporal region), L0 (the line connecting the infraorbital margin with the tragus), and L1 (the line parallel to L0 and passing through FT) such that L2 was positioned 45° from L1 and passed through FT. RESULTS The distance from FT to the superior margin of the orbicularis oculi was 12.3 ± 3.3 mm. The frontalis extended more than 5 cm along L2 in 49 of 49 cases (100%), more than 6 cm in 47 cases (95.9%), more than 7 cm in 34 cases (69.4%), more than 8 cm in 11 cases (22.4%), and more than 9 cm in 3 cases (6.1%). The lateral border of the frontalis ran parallel to and within 1 cm of the medial side of L2. CONCLUSIONS Surface anatomy mapping can assist with predicting the lateral border of the frontalis to minimize the side effects and maximize the efficiency of BoNT-A injections into the forehead.