Effects of exposure length, cortical and trabecular bone contact areas on primary stability of infrazygomatic crest mini-screws at different insertion angles.

BACKGROUND: The infrazygomatic crest mini-screw has been widely used, but the biomechanical performance of mini-screws at different insertion angles is still uncertain. The aim of this study was to analyse the primary stability of infrazygomatic crest mini-screws at different angles and to explore the effects of the exposure length (EL), screw-cortical bone contact area (SCA), and screw-trabecular bone contact area (STA) on this primary stability. METHODS: Ninety synthetic bones were assigned to nine groups to insert mini-screws at the cross-combined angles in the occlusogingival and mesiodistal directions. SCA, STA, EL, and lateral pull-out strength (LPS) were measured, and their relationships were analysed. Twelve mini-screws were then inserted at the optimal and poor angulations into the maxillae from six fresh cadaver heads, and the same biomechanical metrics were measured for validation. RESULTS: In the synthetic-bone test, the LPS, SCA, STA, and EL had significant correlations with the angle in the occlusogingival direction (rLPS = 0.886, rSCA = -0.946, rSTA = 0.911, and rEL= -0.731; all P < 0.001). In the cadaver-validation test, significant differences were noted in the LPS (P = 0.011), SCA (P = 0.020), STA (P = 0.004), and EL (P = 0.001) between the poor and optimal angulations in the occlusogingival direction. The STA had positive correlations with LPS (rs = 0.245 [synthetic-bone test] and r = 0.720 [cadaver-validation test]; both P < 0.05). CONCLUSIONS: The primary stability of the infrazygomatic crest mini-screw was correlated with occlusogingival angulations. The STA significantly affected the primary stability of the infrazygomatic crest mini-screw, but the SCA and EL did not.

Assessing the frequency and variability of accessory zygomatic sutures in dry skulls: clinical insights and potential implications.

PURPOSE: This study aimed to determine the presence and incidence of accessory sutures and bipartite zygomatic bone types, and their effects on population affinity and clinical significance. METHODS: We examined 120 dry skulls and 50 zygomatic bones to evaluate the presence, frequency, and location of accessory zygomatic sutures as well as subtypes of bipartite zygomatic bones. Morphometric analysis included measuring the total width and length of the zygomatic bone with accessory sutures (ASs), the total length of the AS, and the shortest distance between the AS and various anatomical landmarks. RESULTS: Bipartite zygomatic bone was observed in 14 of 120 dry skulls (11.6%) and 1 of 50 zygomatic bones (2%), indicating an overall incidence of 16 occurrences (8.82%). The ASs were predominantly located posterolaterally in 11 cases (six males, five females), anteromedially in two cases (one male, one female), superiorly in one case (male), and superolaterally in one case (male). Significant differences were noted in the distribution of the ASs (p < 0.001). Notably, a vertical inferior bipartite zygomatic type, which has not been reported in the literature, was identified. Correlations were observed between the various anatomical landmarks. Among females, the length of AS was significantly different (p = 0.038). Significant differences were also noted in the shortest distance between the AS and the zygomaticofacial foramen (ZFF) based on the body side (p = 0.034). CONCLUSIONS: Our study suggests that the bipartite zygomatic bone is not a common occurrence, indicating its significance as a morphological variation present in certain individuals. The type VII bipartite zygomatic bone exhibited the highest incidence rate, suggesting potential ethnic-specific differences in the prevalence of certain subtypes. The consistent pattern of suture distribution, along with the asymmetry and variability in suture patterns, emphasizes its potential clinical relevance.

A case series on a new reference in mandibular angles harmonization: the Frontozygomatic-Infraorbital Line (FZ-IOL).

the aim of this paper, is to propose a new reference line: the Frontozygomatic-Infraorbital Line (FZ-IOL). This reference line can guide the surgical team planning mandibular angle harmonization, based on the patient's skeletal proportion. The Frontozygomatic-Infraorbital Line has been adopted for symmetrization surgery, masculinization surgery, and in unsatisfactory results of previous orthognathic surgery. From March 2021 to December 2022, 3 patients were treated for severe facial asymmetry affecting mainly the lower third of the face. All cases were planned with the reference FZ-IOL. Patients were treated in the same center, at the Orthognathic Surgery Department of the Instituto Portugues da Face, Lisbon, Portugal. The Frontozygomatic-Infraorbital Line is designed virtually using software to reconstruct a 3D image from a digital imaging and communications in medicine (DICOM) file obtained from a cone beam computer tomography (CBCT). , connecting the two orbital rims. Then, a vertical line, the frontozygomatic line perpendicular to the IOL and passing through the outmost lateral portion of the frontozygomatic suture is drawn. The proposed line demonstrated how establishing appropriate reference lines is crucial for the success of the surgery. The selection of reference lines should be based on the patient's anatomy, the symmetrization process's complexity, and the surgery's desired outcome. The Frontozygomatic-Infraorbital Line represents an adequate reference line for managing mandibular angle lateral projection, improving lower third of the face symmetrization.

Investigating the Contraction Pattern of the Zygomaticus Major Muscle and its Clinical Relevance: A Functional MRI Study.

BACKGROUND: Our understanding of facial anatomy has significantly evolved, yet the detailed contraction patterns of facial muscles and their presentation during clinical imaging remain largely unexplored. Understanding the contraction patterns and visual presentation of these muscles, particularly the zygomaticus major could enhance pre-surgical facial assessments and the development of new treatment strategies. METHODS: A total of 34 healthy young individuals (17 female, 17 male) with a mean age of 23.6 (2.4) years [range: 20-30] were investigated regarding the length, thickness, width, and angle of the zygomaticus major muscle in five different facial expressions (i.e., repose, anger, joy, surprise, and sadness) utilizing MR imaging. RESULTS: Joyful expressions caused a reduction in muscle length to 85.6% of its original length and an increase in width (103.4%), thickness (108.4%), and facial angle (2.72°) when compared to that in repose, suggesting isotonic contraction. Conversely, expressions of anger, surprise, and sadness generally led to muscle stretching, seen through changes in length (98.9%, 104.3%, and 102.7%, respectively), width (98.8%, 96.5%, and 99.4%, respectively), and thickness (91.2%, 91.0%, and 102.7%, respectively), with variable alterations in facial angle (0.55°, 1.85°, and 1.00°, respectively) depending on the specific expression. CONCLUSION: This MRI-based study indicates that the zygomaticus major muscle experiences isotonic contraction, characterized by decreased length and increased width and thickness. The findings underline the importance of muscle thickness as a reliable parameter in assessing facial muscle function and offer valuable guidance for practitioners in accurately evaluating muscle performance during different facial expressions. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. 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 .

Evaluation of Bone Thickness and Density Values in Resistance Regions in Rapid Maxillary Expansion Using Computed Tomography.

OBJECTIVES: This study used computed tomography (CT) to compare the bone thickness and density values around the zygomaticomaxillary, zygomaticotemporal, and pterygomaxillary sutures that are resistant to rapid maxillary expansion (RME) treatment according to age, sex, and cervical vertebrae maturation (CVM) stage. METHODS: The study included 200 paranasal sinus records obtained for medical diagnosis and examination in a radiology clinic. The records provided data on 110 males and 90 females aged between 4 and 28 years. Bone thickness and density values around the zygomaticomaxillary, zygomaticotemporal, and pterygomaxillary sutures were measured using CT imaging. The correlations of bone thickness and density values with the variables of age, sex, and CVM stage were evaluated. RESULTS: No statistically significant difference was revealed between the bone thickness values around the zygomaticomaxillary and zygomaticotemporal sutures and age, sex, CVM stage, and the right and left regions of the same individual ( P >0.05). A strong correlation was identified between Hounsfield units (Hu) values on bone density in all 3 regions and age and sex ( P <0.001). No correlation was found between the CVM stage and density values around the zygomaticomaxillary, zygomaticotemporal, and pterygomaxillary sutures ( P >0.05). CONCLUSIONS: The Hu values of the records from females were higher than those of males in all age groups. It was observed that with increasing age, bone density values increased in all 3 regions, and thus circummaxillary region's Hu value increased.

Anatomical variations of the zygomaticofacial foramen and its related canal through the zygomatico-orbital and zygomaticotemporal foramina in dry human skulls.

PURPOSE: The aim of this study is to reveal the location of the zygomaticofacial foramina, the variations of their numbers, and their connections between the zygomatico-orbital and zygomaticotemporal foramina. METHODS: Ethics committee approval of our study was received by the Istanbul Medical Faculty Clinical Research Ethics Committee (date:30.07.2021, number:358356). 171 zygomatic bones of unknown gender from the Department of Anatomy, Istanbul University, were included in this study. The number of zygomaticofacial foramina and their connections with the zygomatico-orbital foramen and the zygomaticotemporal foramina were examined. Also, the morphometric distances between the zygomaticofacial foramen were calculated. Evaluation of the data was done with SPPS v.21. RESULTS: The number of zygomaticofacial foramina was found as 299. It was found single, double, three, four, five and six foramina, in 52 (30.4%), 52 (30.4%), 24 (14.03%), 10 (5.85%), 5 (2.93%), 1 (0.58%) zygomatic bone, respectively. Zygomaticofacial foramen was absent in 27 (15.8%) bones. Of these 299 foramina, 129 were found to be connected with zygomatico-orbital foramen and 23 with zygomaticotemporal foramen. It was noted that 147 zygomaticofacial foramina had no connection with any foramina. The distances between the zygomaticofacial foramen and the frontozygomatic suture, temporal process, maxillary process, the lowest point of the zygomatic bone, and orbital rim were found as 25.30 ± 2.81mm, 18.74 ± 3.56mm, 21.56 ± 4.16mm, 18.72 ± 2.57mm, 6.67 ± 3.27mm, respectively. CONCLUSION: Consequently, the location and variations of ZFF are of great importance for maxillofacial surgery and regional block anesthesia. Knowing its location and variations will help prevent complications during any surgical intervention in this region.

Frequency Morphologic and Morphometric Properties and Osseous Relationships of Whitnall's Tubercle.

Whitnall tubercle (WT) of the zygomatic bone is used as an anatomical landmark in some surgical approaches to the orbit. The authors aimed to determine the localization of WT by using some palpable bony landmarks and to reveal its morphological and morphometric features. Three hundred twenty-two zygomatic bones (167 right and 155 left) belonging to adults of unknown sex, were examined. An acetate prepared by drawing a clock with a dial on it was used to determine the localization of WT according to marginal tubercle and zygomatic arch. Distances between WT and frontozygomatic suture and lateral margin of the orbital rim were measured with digital calipers. One zygomatic bone had double tubercles, thus 321 bones were taken into consideration. Whitnall tubercle was determined in 284 of 321 zygomatic bones. 181 were classified as small, 10 as medium, and 93 as large. The position of the WT according to the marginal tubercle was at the 8, 9, and 10 o'clock positions on the left, and at 2, 3, and 4 o'clock on the right. The position of the WT according to the zygomatic arch was at the 9,10 and 11 o'clock positions on the left, and at the 1 and 2 o'clock positions on the right. Distances between the WT and lateral margin of the orbital rim and the frontozygomatic suture were measured meanly as 1.94±0.31 mm and 8.17±5.82 mm, respectively. The authors believe that the data obtained regarding WT will contribute to anatomy and surgical procedures of the related region.

A marginal process of the zygomatic bone predicts a lateral exit of the zygomaticotemporal nerve: An anatomical study with application to surgery around the midface.

Previous studies have not verified the contents of accessory foramina of the zygomatic bone on dry skulls and thus could not conclude whether they carried accessory zygomaticofacial nerve branches or branches or the entire trunk of the zygomaticotemporal nerve (ZTN). Therefore, the aim of the current study is to present findings from cadaveric dissections to clarify this relationship. Fifty, fresh frozen, adult cadaveric sides underwent dissection of the ZTN. When identified, these nerves were quantified and their relationship to the zygomatic bone further documented by dissecting through the bone following the course of the nerve from a superficial to deep perspective. Additionally, 100 dry, adult, human skulls were analyzed looking for lateral foramina on the zygomatic bone. On three cadaveric sides (6%), the ZTN was found to pierce the zygomatic bone deeply and exit its superficial lateral surface. For dry skull specimens, a lateral zygomaticotemporal foramen (ZTF) was identified on nine sides (4.5%). For both groups, the presence of a strong marginal process of the zygomatic bone was strongly correlated to a ZTF exiting the lateral surface of the zygomatic bone. Although relatively uncommon, the ZTN can pierce the lateral aspect of the zygomatic bone and thus can be located superficial to the cheek. Such findings should be borne in mind during surgical or other invasive procedures in this area in order to minimize iatrogenic injury to the ZTN.

The divided zygoma: a meta-analysis of its prevalence with a review of the literature.

BACKGROUND: Divided zygoma (DZ) is an important structure in the midfacial region. The anatomy of DZ is poorly researched, but knowledge about this entity could be useful during posttraumatic facial reconstructions. The aim of this study was to estimate the prevalence and anatomy of DZ in different regions around the world. Therefore, the authors performed a meta-analysis, including all studies that report extractable data on the DZ. MATERIALS AND METHODS: The main online medical databases such as PubMed, EBSCO, ScienceDirect, Web of Science, SciELO, BIOSIS, Current Content Connect, Korean Journal Database and Russian Citation Index, were utilised to gather all studies on anatomical characteristics, prevalence, symmetry, and a number of divisions of zygomatic bone. RESULTS: A total of 20 studies were included in this meta-analysis. Data were grouped and analysed in five categories: (1) prevalence of DZ bone, (2) prevalence of DZ skulls, (3) gender prevalence of DZ with sides, (4) divisions of zygomatic bone, (5) symmetry of DZ. CONCLUSIONS: In conclusion, the authors of the present study believe that this study can be considered an up-to-date meta-analysis regarding the prevalence, divisions, and symmetricity of the DZ. The data provided by the present study may be useful information for physicians in recognizing the DZ of the fracture and may be important information during zygomatic bone osteotomy. Detailed anatomical knowledge of the midfacial region can prevent surgical complications when operating in this area.

Morphometric and morphological evaluation of temporozygomatic suture anatomy in dry adult human skulls.

This study aims to evaluate the position, morphometric, and morphological features of the temporozygomatic suture (TZS) located on the zygomatic arch (ZA) in dry adult human skulls. Thirty-two crania were evaluated. Measurements for the TZS were carried out using the ImageJ software. Morphometric measurements were carried out bilaterally in 23 crania and unilaterally in 9 crania (right: 4, left: 5). A total of 55 TZSs were analyzed. Localization of the TZS was determined according to the reference landmarks on the ZA. Morphologic features of the TZS evaluated in terms of "joint shape type" and "suture margin pattern". Descriptive statistics of the morphometric and morphologic variables were calculated. A statistically significant difference between the right and left sides was observed for the localization of the TZS (p < 0.05). TZS is located more anteriorly on the left side than the right side. Based on the "joint shape type", four types of TZS were observed: Type 1 (angular) (34.55%), Type 2 (curvy) (34.55%), Type 3 (oblique) (14.55%), Type 4 (horizontal) (16.36%). Based on the "suture margin pattern", five types of TZS were observed: Type A (linear) (12.73%), Type B (denticulate) (34.55%), Type C (serrated) (23.64%), Type D (mixt) (21.82%), Type E (fused) (7.27%). No significant association between the type and lateralization was found for both morphologic classifications. To the best of our knowledge, this is the first published report regarding the localization and morphologic classification of the TZS in adult human crania. Considering the TZS with its morphometric and morphological features may contribute to clinical or forensic medical evaluations.

Positional deformation of the parotid gland: Application to minimally invasive procedures.

Anatomical studies of the parotid gland are important for mid- and lower face filler, botulinum toxin, and thread lifting procedures. The purpose of this study was to observe the topographic anatomy of the parotid gland using cadaveric dissections. The superficial lobe of the parotid gland was studied in 30 hemisected heads. Reference lines were made on the lateral aspect of the face. A reference line (the line connecting the mandibular angle to the upper margin of the zygomatic arch, along the posterior border of the ramus) was divided into four sections (P1, P2, P3, and P4). The superior, inferior, anterior, and posterior borders of the parotid gland were measured using the reference lines and sections. Using these measurements, we categorized the superficial lobe of the parotid gland into two types: type Ia, pistol-shaped; Ib, pistol-shaped with an accessory lobe; and type II, oval-shaped. The superior border of the parotid gland started just below the inferior margin of the zygomatic arch. The parotid gland covered the posterior part of the masseter muscle near P1 and P2, but at P3 and below P3, the tail of the parotid gland was located posterior to the ramus and covered the anterior part of the sternocleidomastoid muscle. The topographic anatomy of the parotid gland serves as a reliable reference for esthetic procedures in the lower face and neck region.

Topographic Anatomy of the Zygomatico-Orbital Artery.

ABSTRACT: The zygomatico-orbital artery (ZOA) originating from the superficial temporal artery and supplying the lower temporal region superficially has been reported. Previous studies of this artery have used definitions that are too ambiguous for the results to be directly adapted to clinical practice, including since they have resulted in marked variations in the reported incidence ofthe artery. This study dissected 193 hemifaces of 123 fixed human cadavers aged 36 to 102 years (119 males and 74 females). The authors investigated the ZOA based on the following definition: (1) it originates from the superficial temporal artery, (2) it runs mostly above the zygomatic arch, and (3) it terminates below the superior border of the orbicularis oculi muscle. The incidence of the ZOA was 22.8% (44 cases of 193 sides), and its mean diameter was 1.1 mm. The meanvertical distances from the superior borderofthe zygomatic arch to the artery were 29.6, 17.8, and 2.9 mm at the jugale, zygion, and the origin of the ZOA, respectively. An accurate definition of the ZOA and accurate knowledge of its incidence and course could be important for clinicians to avoid unintentional complications in clinical practice.

Safe Zone for Dissection in Frontotemporal Region to Avoid Injury to the Temporal Branch of Facial Nerve.

ABSTRACT: The objective of this study is to provide a reliable roadmap for temporal branch of the facial nerve, in order to minimize, the risk of injury to the nerve during surgical dissections. A literature search was conducted on temporal branch of facial nerve. The date search range was 1950 to 2017. Databases searched included Medline, Web of science, Biosis, SciELO, Data Citation, and Zoologic Records. Data were collected on, author specialty, date of publication, and the relationship of the temporal branch of facial nerve to various landmarks in the frontotemporal region reported in human anatomic studies. Among the 48 studies reviewed, a total of 3477 anatomic dissections were performed in the craniofacial region. Temporal branch of facial nerve was located between 2.5 and 3 cm from lateral orbital rim. In relation to the zygomatic arch, it was found anywhere from the midpoint of the arch to 1 finger breath posterior to the arch. For the plane, it was most commonly described as being under the superficial temporal fascia (STF) or within the loose areolar tissue. Most anatomic dissections found 2 to 4 twigs of the temporal branch of facial nerve. In relation to the lateral canthus, it was found to be 2.85 +/- 0.69 cm superior and 2.54 +/- 0.43 cm lateral to the lateral canthus. Our study suggests consolidated data on surgical landmarks in order to ensure safe dissection in temporal region and prevent injury to the temporal branch of facial nerve.

Anatomical variations and morphometric study of pterion in a Thai population associated with clinical implications / Variaciones anatómicas y estudio morfométrico del pterion en una población tailandesa asociada con implicaciones clínicas

SUMMARY: The objective of this study was to consider the type of variation and to estimate the landmarks for localizing the pterion. One hundred twenty Thai dry skulls were selected randomly from the Forensic Osteology Research Center, Faculty of Medicine, Chiang Mai University. The distances of the parameters were measured via Vernier caliper. The sphenoparietal type is the most dominant in the Thai population with 88.75 %. In the male, the distance of the midglabella to the pterion was 9.94?0.64 mm The distance of the frontozygomatic suture to the pterion was 35.41?4.38 mm The distance of the zygomatic arch to the pterion was 39.39?4.69 mm and the distance of the mastoid process tip to the pterion was 86.88?4.44 mm In the female, the distance of the midglabella to the pterion was 9.27?0.63 mm The distance of the frontozygomatic suture to the pterion was 33.08?4.12 mm The distance of the zygomatic arch to the pterion was 33.08?4.12 mm and the distance of the mastoid process tip to the pterion was 83.62?5.16 mm. The pterion approach is the most popular method for neurosurgical procedures, and it provides anatomical variations in the pattern. The sphenoparietal type of pterion is the most common form and the stellate type of pterion is the least common form in Thai skulls. Sex influences the location of the pterion. These findings will be of importance to predict the pterion type in Thai skull and estimate the localization of pterion by using a bony landmark. Knowledge of the precise location of the pterion is an important landmark in the neurosurgical approach.

RESUMEN: El objetivo de este estudio fue considerar el tipo de variación del pterion y estimar los puntos de referencia para localizarlo. Se seleccionaron al azar 120 cráneos secos de individuos tailandeses del Centro de Investigación de Osteología Forense de la Facultad de Medicina de la Universidad de Chiang Mai. Las distancias de los parámetros se midieron mediante un caliper Vernier. El tipo esfenoparietal es el más dominante en la población tailandesa con 88,75 %. En el hombre, la distancia de la glabella al pterion fue de 9,94 ? 0,64 mm. La distancia de la sutura frontocigomática fue de 35,41 ? 4,38 mm La distancia del arco cigomático fue de 39,39 ? 4,69 mm y la distancia del ápice del proceso mastoideo al pterion fue de 86,88 ? 4,44 mm. En la mujer, la distancia de la glabella al pterion fue de 9,27 ? 0,63 mm. La distancia de la sutura frontocigomática al pterion fue de 33,08 ? 4,12 mm. La distancia del arco cigomático al pterion fue de 33,08 ? 4,12 mm y la distancia del ápice proceso mastoideo al pterion fue de 83,62 ? 5,16 mm. El abordaje del pterion es el método más utilizado para procedimientos neuroquirúrgicos y proporciona variaciones anatómicas en el patrón. El tipo esfenoparietal del pterion es la forma más común y el tipo estrellado del pterion es la forma menos común en los cráneos tailandeses. El sexo influye en la ubicación del pterion. Estos hallazgos serán importantes para predecir el tipo de pterion del cráneo en tailandeses y a la vez estimar su localización mediante el uso de un punto de referencia óseo. El conocimiento de la ubicación precisa del pterion es un hito impor- tante en el abordaje neuroquirúrgico.

Anatomy and external landmarks of the superficial temporal artery using 3-dimensional computed tomography.

PURPOSE: The purpose of this study was to analyze the anatomical variability of the superficial temporal artery (STA) and to provide an easy visual landmark to find the STA and its branches to facilitate its surgical access. METHODS: A retrospective study was conducted on 57 patients who underwent a head and neck computed tomography with contrast injection. A visual landmark running from the tragus to the corner of the eye was used: the "eye-tragus-line" (ETL). On the ETL, the distance between the tragus and the STA was measured. The length of the STA main branch, its parietal and frontal branch and the angle of the STA and its branches with the ETL were measured. The division of the STA was studied as above/at the same level/below the zygomatic arch (ZA) and the ETL. RESULTS: The STA division was located above the ZA in 61.54% of cases, at the same level in 26.92% of cases and below in 11.54% of cases. Regarding the ETL, 93.27% of the STA divisions were located above the ETL, 5.77% at the same level and 0.96% below. On the ETL, the STA was located 15.55 ± 4.5 mm in front of the tragus. CONCLUSION: This study allowed to define an easy visual landmark: the ETL running from the tragus to the corner of the eye. The STA main branch was located 15.55 ± 4.5 mm of front of the tragus on the ETL. The STA division was nearly always located above the ETL (99.04%). Furthermore, this study provides a statistical representation of the anatomy of the STA and its branches.

Defining a Preauricular Safe Zone: A Cadaveric Study of the Frontotemporal Branch of the Facial Nerve.

BACKGROUND: In the preauricular region, the frontotemporal branch of the facial nerve is vulnerable to injury, which can result in facial palsy and poor cosmesis after surgical interventions. OBJECTIVES: The purpose of this study was to describe variations in the branching patterns of the frontotemporal branch of the facial nerve and the relation between this branch and the surrounding anatomic landmarks. Based on our findings, we propose a Danger Zone and Safe Zones for preauricular interventions to avoid frontal branch injury. METHODS: Twenty cadaveric half-heads, 10 freshly frozen and 10 embalmed, were dissected. The anatomy of the auriculotemporal nerve, facial nerve, and variations of its branching pattern in the preauricular region were investigated. RESULTS: The mean [standard deviation] number of frontotemporal branches crossing the zygomatic arch was 2.05 [0.6]. Beginning from the X point at the apex of the intertragal notch, frontal branches ran over the zygomatic arch at a distance extending from 10 to 31 mm anterior to the tragus, which can be defined as the Danger Zone for frontal branches. Safe Zones A and B are triangular regions located behind and in front of the Danger Zone, respectively. CONCLUSIONS: Mapping of these Safety and Danger Zones is a reliable and simple approach in preauricular interventions to avoid frontal branch injury because the facial nerve typically has multiple frontal branches. This approach provides practical information for surgeons rather than estimating the trajectory of a single frontal branch from Pitanuy's line.

Anatomic Study Quantifying the Relationship Between the Arcuate Eminence and the Root of the Zygoma: Application to Skull Base Surgery.

OBJECTIVE: The aim of this study was to define the structural relationship between the arcuate eminence (AE) and a known fixed external bony landmark, the root of the zygoma (ZR), and to determine its reliability as a consistent guide for guiding surgical approaches. To our knowledge, this is the only anatomic study to quantify the relationship between the AE and ZR. METHODS: Twenty-one dry temporal bones were measured using digital calipers. The distance from the posterior aspect of the ZR to the midpoint of the AE was measured. Additionally, the anteroposterior distance between the ZR and AE and vertical distance between the 2 structures were measured. Student's t-test was used to compare the left and right sides. RESULTS: An AE was found in every specimen. The mean ZR to AE distance was 30.9 mm. On most sides (91%), the ZR was located more inferiorly than the AE with a mean distance of 3 mm between the 2 structures. The mean distance between the AE and ZR was 17 mm. On all sides, the AE was located posterior to the ZR. No significant differences were found between sides. No anatomic variations or pathologic conditions were noted in any of the specimens. CONCLUSIONS: The ZR is an easily identifiable and consistent bony landmark often used by skull base surgeons. In this investigation, we measured the anatomic relationships between the ZR and AE. Such data might assist in planning surgical trajectories and minimizing complications when skull base pathologies are approached.

A 3D comparison of dimension of infrazygomatic crest region in different vertical skeletal patterns: A retrospective study.

INTRODUCTION: Infrazygomatic crest (IZC) dimension is an important factor in the safety and stability of bone screws. The dimension is known to vary according to the dimensions of the maxillary sinus, which in turn depends on the vertical facial skeletal pattern. OBJECTIVE: The objective of the study was to compare the infrazygomatic crest thickness (IZC) above the mesiobuccal root of the first and second maxillary molar in different vertical skeletal patterns. MATERIALS AND METHODS: This was a retrospective study conducted in Saveetha Dental College, Chennai. Cone beam computed tomography (CBCT) and lateral cephalograms of 36 subjects were collected and divided into 3 groups (12 subjects in each group) depending on their vertical skeletal pattern, namely normal, low and high angle. Vertical skeletal pattern was assessed using lateral cephalogram whereas IZC thickness was measured using CBCT. Mann Whitney U test was done to compare the bone thickness in the right and left sides and also to compare the same above the mesiobuccal root of the first and second molar. Kruskal Wallis and post hoc tests were done to compare bone thickness among the three groups. P-value was set at 0.05 for all the analysis. RESULTS: Significant difference in IZC bone thickness above the first molar region was noted between high angle and average angle groups (P-value 0.001) and high angle and low angle (P-value 0.001). Above the second molar region, a significant difference was seen between high angle and average angle groups (P-value 0.001). Significant difference in bone thickness was also observed among the first molar and second molar region in all the three groups (P-value<0.05). CONCLUSION: IZC thickness was the least in high-angle subjects. Clinically, it is desirable to place the IZC screw above the mesiobuccal root of the maxillary second molar especially in high-angle subjects.

Morphology of the pterion in Serbian population / Morfología del pterion en población serbia

The pterion is a topographic point on the lateral aspect of the skull where frontal, sphenoid, parietal and temporal bones form the H or K shaped suture. This is an important surgical point for the lesions in anterior and middle cranial fossa. This study was performed on 50 dry skulls from Serbian adult individuals from Department of Anatomy, Faculty of Medicine in Novi Sad. The type of the pterion on both sides of each skull was determined and they are calcified in four types (sphenoparietal, frontotemporal, stellate and epipteric). The distance between the center of the pterion and defined anthropological landmarks were measured using the ImageJ software. Sphenoparietal type is predominant with 86 % in right side and 88 % in left side. In male skulls, the distance from the right pterion to the frontozygomatic suture is 39.89±3.85 mm and 39.67±4.61 mm from the left pterion to the frontozygomatic suture. In female skulls the distance is 37.38±6.38 mm on the right and 35.94±6.46 mm on the left. The shape and the localization of the pterion are important because it is an anatomical landmark and should be used in neurosurgery, traumatology and ophthalmology.

El pterion es un punto topográfico en la cara lateral del cráneo donde los huesos frontales, esfenoides, parietales y temporales forman la sutura en forma de H o K. Este es un punto quirúrgico importante para las lesiones en la fosa craneal anterior y media. Este estudio se realizó en 50 cráneos secos de adultos serbios del Departamento de Anatomía de la Facultad de Medicina de Novi Sad. Se determinó el tipo de pterión en ambos lados de cada cráneo y se calcifican en cuatro tipos (esfenoparietal, frontotemporal, estrellado y epipterico). La distancia entre el centro del pterion y los puntos de referencia antropológicos definidos se midió utilizando el software ImageJ. El tipo esfenoparietal es predominante con 86 % en el lado derecho y 88 % en el lado izquierdo. En los cráneos masculinos, la distancia desde el pterion derecho hasta la sutura frontocigomática es 39,89 ± 3,85 mm y 39,67 ± 4,61 mm desde el pterion izquierdo hasta la sutura frontocigomática. En los cráneos femeninos, la distancia es 37,38 ± 6,38 mm a la derecha y 35,94 ± 6,46 mm a la izquierda. La forma y la localización del pterion son importantes debido a que es un indicador anatómico y debe usarse en neurocirugía, traumatología y oftalmología.

Correlation analysis of infraorbital foramen with related anatomical structures / Análisis de correlación del foramen infraorbitario con estructuras anatómicas relacionadas

The anatomical localization of foramen infraorbitale (FOI) and its relationship with ambient structures are of great importance for clinicians and surgeons. This study was performed on seventy five skulls, and the distance between FOI to important anatomical formations, angular position of the zygomatic bone and the relationship between these parameters were investigated on both sides. The distance of FOI to margo infraorbitalis (MI), apertura piriformis (AP) and spina nasalis anterior (SNA), upper face height (UH) and upper face width (UW) were measured. Zygomatic bone triangle angles (SA, PA, IA) and porion-nasion-spina nasalis anterior angle (PNS) were measured from lateral view of the skull. While there was no significant difference between right and left measurement except for PA (p=0.03), the distance from FOI to MI is showed a very high degree positive correlation between the right and left sides, the distance from the FOI to AP was weak correlated only right side.

La localización anatómica del foramen infraorbitario (FIO) y su relación con las estructuras adyacentes son de gran importancia para los médicos y cirujanos. Este estudio se realizó en setenta y cinco cráneos, y se investigó la distancia entre FIO a formaciones anatómicas importantes, la posición angular del hueso cigomático y la relación entre estos parámetros en ambos lados. Se midió la distancia de FIO al margen infraorbitario (MI), apertura piriforme (AP) y espina nasal anterior (ENA), altura superior de la cara (AC) y ancho superior de la cara (AC). Los ángulos del triángulo óseo cigomático y el ángulo anterior porion-nasion-epina nasal se midieron desde la vista lateral del cráneo. Si bien no hubo una diferencia significativa entre la medición derecha e izquierda, a excepción AP (p = 0,03), la distancia de FIP a MI mostró una correlación positiva de alto grado entre los lados derecho e izquierdo, la distancia de FIO a AP fue débil correlacionado solo en el lado derecho.