Consideration of the diameter of superficial temporal arteries related to filler injections in the temporal region.

BACKGROUND: The concavity of the temple due to adipose tissue atrophy from aging accentuates the zygomatic arch and lateral orbital rim, leading to an aged appearance. The use of hyaluronic acid filler in the temporal region has gained popularity due to its procedural simplicity and consistent outcomes. OBJECTIVE: To evaluate the safety of administering hyaluronic acid filler in the temporal region concerning the frontal branch of the superficial temporal artery, which is at risk of injury. METHODS: Empirical observations were conducted on the internal diameter of the frontal branch of the superficial temporal artery, a critical anatomical site for potential injury. RESULTS: A significant proportion of the artery segments exhibited an internal diameter below 1 mm. Given that the outer diameter of an 18-gauge cannula is 1.27 mm, this method can be considered a relatively secure approach for enhancing the temporal region. CONCLUSION: The use of an 18-gauge cannula for hyaluronic acid filler administration in the temporal region appears to be a safe and effective method, with the potential risk to the frontal branch of the superficial temporal artery being minimal.

A novel description of the supporting system of the orbicularis oculi muscle in the infraorbital area: Tear trough muscle fiber.

BACKGROUND: The aim of this study was to elucidate the anatomical structures of supporting system of the infraorbital area. MATERIALS AND METHODS: Forty-four hemifaces from eleven Korean and eleven Thai cadavers were used to dissect the infraorbital area. Based on the dissection and previous histologic results, they were analyzed. RESULTS: The orbicularis oculi muscle (OOc) had two portions (palpebral and orbital portion) and four subparts (pretarsal, preseptal, prezygomatic, and premaxillary part). The elliptical muscle fiber of OOc was supported by circumferential connective tissue including skin ligament, orbicularis retaining ligament, zygomatic ligament, and zygomatic cutaneous ligament. The vertical muscle fiber, the tear trough muscle fiber, and medial muscular band directly attached to the skin. CONCLUSION: Full of subcutaneous tissue in the tear trough groove, strong attachment to the bone by tear trough ligament and to the skin by tear trough muscle fiber would multiply result in the tear trough on the face.

Comparative study of 360° virtual reality and traditional two-dimensional video in nonface-to-face dental radiology classes: focusing on learning satisfaction and self-efficacy.

BACKGROUND: Acquiring adequate theoretical knowledge in the field of dental radiography (DR) is essential for establishing a good foundation at the prepractical stage. Currently, nonface-to-face DR education predominantly relies on two-dimensional (2D) videos, highlighting the need for developing educational resources that address the inherent limitations of this method. We developed a virtual reality (VR) learning medium using 360° video with a prefabricated head-mounted display (pHMD) for nonface-to-face DR learning and compared it with a 2D video medium. METHODS: Forty-four participants were randomly assigned to a control group (n = 23; 2D video) and an experimental group (n = 21; 360° VR). DR was re-enacted by the operator and recorded using 360° video. A survey was performed to assess learning satisfaction and self-efficacy. The nonparametric statistical tests comparing the groups were conducted using SPSS statistical analysis software. RESULTS: Learners in the experimental group could experience VR for DR by attaching their smartphones to the pHMD. The 360° VR video with pHMD provided a step-by-step guide for DR learning from the point of view of an operator as VR. Learning satisfaction and self-efficacy were statistically significantly higher in the experimental group than the control group (p < 0.001). CONCLUSIONS: The 360° VR videos were associated with greater learning satisfaction and self-efficacy than conventional 2D videos. However, these findings do not necessarily substantiate the educational effects of this medium, but instead suggest that it may be considered a suitable alternative for DR education in a nonface-to-face environment. However, further examination of the extent of DR knowledge gained in a nonface-to-face setting is warranted. Future research should aim to develop simulation tools based on 3D objects and also explore additional uses of 360° VR videos as prepractical learning mediums.

Accessory nerve distribution for aesthetic botulinum toxin injections into the upper trapezius muscle: anatomical study and clinical trial : Reproducible BoNT injection sites for upper trapezius.

PURPOSE: The descending part of the trapezius muscle is clinically associated with neck pain and aesthetic applications. The innervation of the trapezius muscle is not well described in the medical literature for clinicians. The aim of study was to analyze the perforating branch pattern of the accessory nerve in the descending part of the trapezius muscle with the aim of describing the most efficient and reproducible BoNT injection sites for aesthetic treatment of shoulder contouring. METHODS: Twenty-six specimens (five male and eight female) from embalmed Korean cadavers were used in this study. The trapezius muscle was dissected scrupulously and then reflected to enable examination of the locations of the perforating points. The thickness of trapezius muscle was measured in 13 volunteers using a diagnostic ultrasonography system. BoNT was injected into the trapezius muscle bilaterally. Injections were performed at 6 points separated by 2 cm. The muscle thicknesses were measured three times using ultrasonography: before the injection and at 4 and 12 weeks after the injection. RESULTS: The dense arborization of the perforating accessory nerve branches was confined mostly to section b (66.7%, 54/81) and section c (33.3%, 27/81). The mean muscle thickness at 4 and 12 weeks consistently decreased 0.68-0.63 cm  in conventional method and 0.65-0.61 cm in new method (NDM) respectively (right and left). CONCLUSION: To optimize the outcome of BoNT injection, we recommended injecting into six points separated by 2 cm in sections b and c of the upper trapezius muscle. It is significant that it is easier to apply to anyone than to apply unstructured techniques.

Does Botulinum Toxin Injection into Masseter Muscles Affect Subcutaneous Thickness?

BACKGROUND: Botulinum toxin (BoNT) is widely used to treat masseter muscle hypertrophy. Changes in the muscle thickness have been found in many studies, but there has been no report on changes in the thickness from the skin surface to the masseter muscle. OBJECTIVES: We aimed to use ultrasonography to measure not only changes in the muscle thickness but also changes in subcutaneous thickness. METHODS: This study enrolled 20 volunteer patients: 10 were assigned to an experimental group (injected with each side 25 U of botulinum toxin into both masseter muscles) and 10 to a control group (injected with normal saline). The thicknesses were measured before the injection and at 4, 8, and 12 weeks after the injection both at rest and during maximum muscle contraction. RESULTS: The subcutaneous thickness did not differ significantly over time either at rest (P = 0.063) or during maximal contraction (P = 0.392), or between the experimental and control groups at rest (P = 0.392) or during maximum contraction (P = 0.259). The muscle thickness in the experimental group differed significantly over time. CONCLUSIONS: Botulinum toxin injection only changes the muscle thickness and does not affect the subcutaneous thickness from the skin surface to the masseter muscle.

Anatomical insights of the palmaris brevis muscle for clinical procedures of the hand.

The purpose of the present study is to provide useful data for anatomists and clinicians by describing the topography of the palmaris brevis muscle, taking particular note of its morphology and distribution pattern of the nerve and artery. Forty-nine hands from Korean adult cadavers were used in this study. Parameters with respect to the size, scale, and location of the muscle were measured using a ultrasonography system, digital caliper, and surgical microscope. Histologic sections were obtained to clarify the positional relationship with surrounding tissues. The branches of the ulnar nerve and artery, which supply the muscle, were observed. The minimum and maximum depths in which the palmaris brevis muscle can be existed, including the thickness of the skin (1.9 mm), were 3.7 and 6.9 mm, respectively. It was inserted into the hypothenar fascia and the dermis. The main trunk of the ulnar nerve and artery were positioned under the lateral side of the muscle. The richest arborization of perforating branches of the ulnar nerve and artery was mostly confined to the distal section of the lateral side of the muscle. Our findings provide theoretical evidence of the palmaris brevis muscle for clinical procedures of the hand, such as botulinum toxin injection. Clinicians should pay attention not to injure the ulnar artery under the lateral side of the muscle. Botulinum toxin should be injected at a depth of between approximately 2 and 7 mm, considering the range of depth of the muscle. Clin. Anat. 30:397-403, 2017. © 2017 Wiley Periodicals, Inc.

Anatomical recommendations for safe botulinum toxin injection into temporalis muscle: a simplified reproducible approach.

PURPOSE: The objective of this study was to simplify the anatomically safe and reproducible approach for BoNT injection and to generate a detailed topographic map of the important anatomical structures of the temporal region by dividing the temporalis into nine equally sized compartments. METHODS: Nineteen sides of temporalis muscle were used. The topographies of the superficial temporal artery, middle temporal vein, temporalis tendon, and the temporalis muscle were evaluated. Also evaluated was the postural relations among the foregoing anatomical structures in the temporalis muscle, pivoted upon a total of nine compartments. RESULTS: The temporalis above the zygomatic arch exhibited an oblique quadrangular shape with rounded upper right and left corners. The distance between the anterior and posterior margins of the temporalis muscle was equal to the width of the temporalis rectangle, and the distance between the reference line and the superior temporalis margin was equal to its height. The mean ratio of width to height was 5:4. CONCLUSIONS: We recommend compartments Am, Mu, and Pm (coordinates of the rectangular outline) as areas in the temporal region for BoNT injection, because using these sites will avoid large blood vessels and tendons, thus improving the safety and reproducibility of the injection.

Neuromuscular structure of the tibialis anterior muscle for functional electrical stimulation.

PURPOSE: This study describes the nerve entry points and intramuscular nerve branching of the tibialis anterior, providing essential information for therapeutic functional electrical stimulation and botulinum toxin injection. METHODS: One hundred and ten legs from Korean and Thai cadavers were dissected. Ten specimens were harvested and subjected to modified Sihler's staining. RESULTS: The average total length from the lateral malleolus to the fibular head was 32.0 cm (SD 1.9). The nerve entry points were densely distributed between 86.5 and 90.6 % of the reference length, where the first and second nerve entry points were observable. A densely arborizing area of the intramuscular nerve branches was observed at 70-80 % of the reference length. CONCLUSIONS: Based on the results of this study, clinicians can increase the effectiveness of therapeutic functional electrical stimulation and identify the ideal sites for botulinum toxin injection to the tibialis anterior muscle.

Blending of the lateral deep slip of the platysma muscle into the buccinator muscle.

PURPOSE: The aim of this study was to clarify the prevalence of blending of the lateral deep slip of the platysma into the buccinator, and the morphologic and spatial relationships thereof. METHODS: The lateral deep slip of the platysma was investigated in 42 specimens of embalmed adult Korean cadavers. RESULTS: The lateral deep slip of the platysma was observed in 17 of the 42 specimens (40.5 %). When present, it divided from the deep portion (16 specimens, 38.1 %) or the lateral portion (1 specimen, 2.4 %) of the platysma pars modiolaris. The lateral deep slip passed deep to the facial artery, where it blended into the inferior part of the buccinator. The blending site was located inferolateral to the modiolus. After blending into the buccinator, the fibers of the lateral deep slip coursed longitudinally with the inferior fibers of the buccinator. CONCLUSION: The present description of the topography of the lateral deep slip of the platysma and its relationship with surrounding structures could improve the understanding of the detailed movements of the lower face and the related EMG activities, with the data also being useful when performing facial surgery.

An anatomical study of the risorius in Asians and its insertion at the modiolus.

PURPOSE: Detailed explanations of the insertion, interaction patterns, and arrangement of the risorius muscle fibers at the modiolus have still not been clearly shown. The aim of this study is to clarify the arrangement of the risorius muscle by means of topographic examination, and to evaluate the anatomical variations in its attachments and pattern of shape to other perioral muscles, and eventually to understand the various features of the facial animation of Asians. MATERIALS AND METHODS: Eighty embalmed Korean and Thai adult hemifaces from cadavers of both genders were dissected in this study. Detailed dissection at the modiolus revealed the insertion of the risorius muscle in relation to its attachments and fiber interaction forms. RESULTS: When categorized into three common anatomical types--zygomaticus risorius (ZR), platysma risorius (PR), and triangularis risorius (TR). PR was most common with 45 % (36 cases) frequency. Risorius muscle also inserted into the modiolus in three distinct layers in relation to the depressor anguli oris: superficial, flush, and deep. Superficial attachment was most commonly found with 56.3 % (45 cases) frequency. CONCLUSIONS: These results will provide critical information for future planning and performing of reconstructive, reanimation, and cosmetic surgical procedures for cases such as developmental defect, facial trauma, facial muscle paralysis, and restoring the natural personal appearances.

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.

Anatomical considerations of the longitudinal pharyngeal muscles in relation to their function on the internal surface of pharynx.

The aim of this study was to clarify the topography of the longitudinal pharyngeal muscles and to relate the findings to pharyngeal muscular function. Forty-four specimens (22 right and 22 left sides) from embalmed Korean adult cadavers (13 males, 9 females; age range, 46-89 years; mean age, 69.2 years) were used in this study. The palatopharyngeus muscle originated from the palatine aponeurosis and the median part of the soft palate on oral aspect; it ran downward and lateralward, respectively. The palatopharyngeus muscle, which held the levator veli palatini, was divided into two bundles, medial and lateral, according to the positional relationship with the levator veli palatini. The lateral bundle of the palatopharyngeus muscle was divided into two parts: longitudinal and transverse. The pharyngeal longitudinal muscles were classified into the following four types (I-IV) depending on the area of insertion: they were inserted into the palatine tonsil, epiglottis, arytenoid cartilage, piriform recess, thyroid cartilage, and pharyngeal wall. The transverse part of the palatopharyngeus muscle plays a role as a sphincter. Palatopharyngeus and levator veli palatini muscles help each other to function effectively in the soft palate. The present findings suggest that the pharyngeal muscles are involved not only in swallowing but also in respiration and phonation via their attachment to the laryngeal cartilage.

Topography of the greater palatine artery and the palatal vault for various types of periodontal plastic surgery.

The purpose of the present study is to provide useful data that could be applied to various types of periodontal plastic surgery by detailing the topography of the greater palatine artery (GPA), looking in particular at its depth from the palatal masticatory mucosa (PMM) and conducting a morphometric analysis of the palatal vault. Forty-three hemisectioned hard palates from embalmed Korean adult cadavers were used in this study. The morphometry of the palatal vault was analyzed, and then the specimens were decalcified and sectioned. Six parameters were measured using an image-analysis system after performing a standard calibration. In one specimen, the PMM was separated from the hard palate and subjected to a partial Sihler's staining technique, allowing the branching pattern of the GPA to be observed in a new method. The distances between the GPA and the gingival margin, and between the GPA and the cementoenamel junction were greatest at the maxillary second premolar. The shortest vertical distance between the GPA and the PMM decreased gradually as it proceeded anteriorly. The GPA was located deeper in the high-vault group than in the low-vault group. The premolar region should be recommended as the optimal donor site for tissue grafting, and in particular the second premolar region. The maximum size and thickness of tissue that can be harvested from the region were 9.3 mm and 4.0 mm, respectively.

Surgical consideration of the anatomic origin of the risorius in relation to facial planes.

BACKGROUND: Confusion exists as to the plane of the risorius with respect to the superficial musculoaponeurotic system (SMAS), the parotid fascia, and the masseteric fascia, which generally are considered origins of the risorius. OBJECTIVES: The authors attempted to clarify the origin of the risorius by topographic examination and dissection, which would provide valuable anatomic information for flap dissection in facelift surgery. METHODS: Detailed dissection was performed in the perioral region of 46 cadaveric specimens to discern the origin of the risorius in relation to the fascial layer. The anatomic aspects of the muscular arrangement and origin of the risorius were classified according to the location of attachment. RESULTS: The risorius originated solely from the fascial layer superficial to the SMAS in 27 specimens (58.7%; type A). It originated solely from the masseter tendon in 3 specimens (6.5%; type B) and from the fascial layers, both superficial and deep to the SMAS, in 16 specimens (34.8%; type C). CONCLUSIONS: The patterns of risorius origination identified in this study represent important anatomic reference information for flap dissection in facelift surgery.

A novel histologic description of the fibrous networks in the lid-cheek junction and infraorbital region.

The aim of this study was to identify the anatomical feature of retaining ligament and fat compartment on the lower eyelid and infraorbital region using a histological method, and to investigate clear definitions for them which could be used generally in the clinical area. Eighteen specimens from eight fresh Korean cadavers were stained with Masson trichrome or hematoxylin and eosin. The ligamentous and fascial fibrous tissue were clearly identified. The ligamentous fibrous tissue which traversed in the superficial and deep fat layer was skin ligament and orbicularis retaining ligament (ORL). The fascial fibrous tissue enclosed the orbicularis oculi muscle (OOc) and circumferencial adipose tissue. Based on the ligamentous and fascial structure, three fat compartments, septal, suborbicularis oculi and infraorbital fat compartment, could be identified. The OOc attached to orbital rim and dermis by ORL and skin ligament, and the muscle fascicle and fat fascicle provided the connection point to the ORL and skin ligament as enclosing all muscle and fat tissue. The combination of the force made by the skin ligament in the lower eyelid and ORL may decide the level and form of the infraorbital grooves.

Effective Locations for Injecting Botulinum Toxin into the Mentalis Muscle; Cadaveric and Ultrasonographic Study.

The mentalis muscle is now considered key structures when performing procedures for rejuvenating the lower face. The aim of this study was to determine the anatomical morphology and location of the mentalis muscle and thereby provide anatomical information for facilitating clinical procedures designed to rejuvenate the lower face. Forty-four adult hemifaces from five Thai cadavers and 21 Korean cadavers were dissected to identify the locations of the mentalis muscle. Sixty-six hemifaces from 33 healthy young Korean subjects were included in an ultrasonographic study. The depth of the mentalis muscle below the skin surface, the thickness of the mentalis muscle, and the distance from the bone to the mentalis muscle were measured at the two points that were 5 mm lateral to the most-prominent point of the chin. The mentalis muscle was classified into two types based to its shape: in type A (86.4%, 38 of the 44 cases) it was dome shaped in three dimensions, while in type B (13.6%, 6 of the 44 cases) it was flat. The mentalis muscle was present mostly at the area 5-10 mm from the midsagittal line and 20-30 mm from a horizontal line connecting the mouth corners. The mentalis muscle was present between depths of 6.7 to 10.7 mm below the skin. This new information about the location of the mentalis muscle may help when identifying the most effective and safe botulinum toxin injection points and depths during esthetic procedures for weakened facial rhytides on the lower face.

Anatomical variations of the stylopharyngeus and superior constrictors in relation to their function.

The aims of this study were to clarify the topography and variations stylopharyngeus (STP) and superior constrictor (SC) muscles, and to examine what role they play in the pharyngeal movement. Forty-four specimens (22 right and 22 left sides) from embalmed Korean adult cadavers (13 males, 9 females; age range, 46-89 years; mean age, 69.2 years) were used in this study. The accessory bundle of STP and petropharyngeus was found in 18.2% (8/44) and 25.0% (11/44) of cases, respectively. A variation of the STP, in which it ran transversely and merged with the SC muscle, was found in 2.3% (1/44) of cases while a variation of the SC muscle, in which it ran longitudinally and merged with the contralateral constrictors, was found in 11.4% (5/44). The variant muscle bundles play their own role in pharyngeal movement according to their morphology. These results provide information that will help a comprehensive understanding of the effects of pharyngeal muscles on movement.

A Proposal for Botulinum Toxin Type A Injection Into the Temporal Region in Chronic Migraine Headache.

Botulinum toxin type-A (BTX-A) injection for treating chronic migraine (CM) has developed into a new technique covering distinct injection points in the head and neck regions. The postulated analgesic mechanism implies that the injection should be administered to sensory nerves rather than to muscles. This study aimed to determine the topographical site of the auriculotemporal nerve (ATN) and to propose the effective injection points for treating CM. ATNs were investigated on 36 sides of 25 Korean cadavers. The anatomical structures of the ATN were investigated focusing on the temporal region. A right-angle ruler was positioned based on two clearly identifiable orthogonal reference lines based on the canthus and tragus as landmarks, and photographs were taken. The ATN appeared superficially in the anterosuperior region of the tragus. The nerve is located deeper than the superficial temporal artery. And it runs between the artery and the superficial temporal vein. In the superficial layer, it is divided into anterior and posterior divisions. The anterior division runs in a superior direction, while the posterior division runs in front of the ear and the several branches are distributed to the skin. We suggest that the optimal BTX-A injection points for CM are in the temporal region. The first point is about 2 cm anterior and 3 cm superior to two orthogonal reference lines defined based on the tragus and canthus, and the second point is about 4 cm superior to the first point. The third and fourth points are recommended about 2 cm superior to the first point, but respectively 1 cm anterior and posterior to it.

Topography of the dorsal nasal artery and its clinical implications for augmentation of the dorsum of the nose.

BACKGROUND: Injections of filler into the nose for dorsum augmentation have a higher risk of complications due to the complicated blood supply and anastomotic channels in this area. OBJECTIVES: The aim of this study was to determine the anatomical features and location of the dorsal nasal artery (DNA), and to provide clinical anatomical information to reduce side effects and severe complications in the perinasal area. METHODS: Using the 31 cadaveric noses in Asians, dissections and histologic examinations were performed to identify the location and depth of the vascular structures including DNA. RESULTS: Dorsal nasal artery ran downward at 20.3 ± 3.5 mm from the intercanthal line and the communicating branch that connected the bilateral DNAs was located 8.5 ± 3.5 mm inferior to the intercanthal line. The DNA was located at 4.4 ± 3.2 mm, 4.6 ± 4.4 mm, and 5.2 ± 4.4 mm lateral to the midline of the nose on the intercanthal, quadrisected, and bisected lines, respectively. At the level of nasal bone, DNA was located superficial to the muscular layer and it runs inferolaterally on dorsum on nose. It was running more deeply and located beneath the fibromuscular layer at the cartilaginous portion of the dorsum of nose. CONCLUSIONS: Injection into deep fatty layer may reduce the risk of arterial injury and the consequent complications. However, in a hooked nose, the tip of the needle traveling along the deep layer approaches the superficial layer due to the convexity of the hump as it passes over it, which can increase the probability of damaging the DNA.