Use of bone landmarks for assessing the safety of acupuncture on the posterior midline of the neck region.

OBJECTIVE: Many acupuncture acupoints are located on the posterior midline of the neck region. The needling depth for acupuncture is important for practitioners, and an unsafe needling depth increases the possibility of damage to the spinal cord and brainstem. Can the safety of acupuncture be assessed by examining bone structures? We focused on this aim to carry out this study. METHODS: The shortest distance from the posterior border of the foramen magnum to the line joining both upper ends of the posterior border of the mastoid process was measured on 29 skulls. Distances from the posterior border of the vertebral foramen to the tip of the spinous process and posterior tubercle of the atlas were measured and evaluated from 197 dry cervical vertebrae and 31 lateral cervical radiographs of patient subjects. The anatomic relationships of the vertebral canal with the external occipital protuberance, tip of the spinous process of the axis, tip of the posterior tubercle of the atlas, and upper end of the posterior border of the mastoid process were observed and evaluated via lateral cervical radiography. RESULTS: The shortest distance from the foramen magnum to the line between the mastoid processes was 4.65±1.75 mm, and the distance from the superior border of the vertebral foramen of the atlas to the posterior tubercle was less than the distance from the inferior border. The distance from the superior border of the vertebral canal to the tip of the spinous process in C2-C7 was greater than the distance from the inferior border. The mean lengths of the superior border of the C2 spinous process and the inferior border of the C7 spinous process were greater than 21 mm and 31 mm, respectively. The line from the upper end of the posterior border of the mastoid process to the tip of the C2 spinous process or 10 mm deep to the tip of the C2 spinous process was posterior to the vertebral canal. CONCLUSIONS: On the posterior midline of the neck region between the tip of spinous process of axis and external occipital protuberance, if the needle reaches the depth of the line between the upper end of posterior border of mastoid process and the tip of the spinous process of the axis, approximately 10 mm along the spinous process of the axis, the needle is in the safe region. The mean length of the C2-C7 spinous process is suitable to accommodate the needling depth of the adjacent acupoint. Bone structures can be used to effectively assess the safety of acupuncture on the posterior midline of the neck region.

Selected structures of middle ear relevant to cochlear implantation on the basis of computer tomography.

BACKGROUND: The primary objective of this study was to analyze middle ear structures critical for cochlear implantation using computed tomography. MATERIALS AND METHODS: Patients who underwent cochlear implantation at the Department of Otolaryngology in Szczecin between 2015 and 2022 were eligible for the study. We analyzed computed tomography images of 57 ears in 52 patients. The following parameters were assessed: mastoid aeration, tegmen tympani height, sigmoid sinus position, posterior tympanotomy width, the distance between the facial nerve and chorda tympani, modified facial recess distance, and the prediction line described by other authors. RESULTS: In 69% of patients, after the removal of the round window bony overhang, the round window membrane became fully visible. There were no statistically significant correlations found for parameters describing mastoid process anatomy or those rating the width of the posterior tympanotomy concerning round window access. The prediction lines, according to Kashio and Jwair, were found to be relevant. In cases where patients' access to the niche and membrane of the window was rated as good or very good during clinical evaluation, they were more likely to describe the window as being located posteriorly or medially in the radiological evaluation. Using a binary Jwair scale provided a better correlation with the clinical assessment. In cases where the windows were graded as posterior, the clinical assessment indicated better surgical access, especially to the RWM (Round Window Membrane). CONCLUSIONS: Evaluating middle ear anatomy on a computed tomography scan is useful for preparing for middle ear surgery but does not significantly affect the ability to access the round window. For such access, the position of the window in relation to the facial nerve is the most relevant factor, and measurements based on this relationship hold the highest clinical value.

Anatomy of the mastoid triangle and morphometric sex differences.

OBJECTIVE OF THE STUDY: This study aimed to quantify the area of the mastoid triangle (MT) and assess potential morphometric differences between males and females. PATIENTS: The sample consisted of 244 dry human skulls, with biological sex known based on genetic analysis, collected from a medicolegal osteological database from Central-Western Brazil. MATERIALS AND METHODS: The study was observational, analytical, and cross-sectional. The skulls were analyzed using Heron's equation to calculate the area of the MT. The landmarks connecting each of the sides of the triangle were: Porion (Po)>Mastoidale (Ma)>Asterion (Ast). Morphometric references were calculated and compared based on sex. RESULTS: The area of the MT was nearly 14% larger in males compared to females (p<0.05). The mean MT area for the right and left sides of males were 684.11±93.25mm2 and 668.94±111.95mm2, respectively. In females, the mean MT for the right and left sides were 588.93±91.09mm2 and 582.88±102.98mm2, respectively. Right and left side measurements were significantly different (p<0.05), except for Po-Ast (p=0.232). CONCLUSION: Morphometric features regarding the MT were slightly different between males and females. Application of the MT as a dimorphic tool should be adjuvant. Moreover, this tool should be considered carefully, especially because the sex-based differences were statistically significant, but discrete between males and females.

Topography of the Anatomical Landmarks of Carotid Bifurcation and Clinical Significance.

OBJECTIVE: Carotid bifurcation (CB) and its terminal branches are the most common sites of atherosclerotic plaques. In surgical treatment, these plaques can be reached by an endarterectomy technique. The success of the technique can be achieved with good anatomical knowledge of these arteries and their relationships with surrounding structures. MATERIALS AND METHODS: The study was performed retrospectively on archived images of patients with computed tomography angiography (CTA). Two hundred forty-seven patients who met the criteria were included in this study. Three-dimensional (3D) reconstructions of two-dimensional CTA images were made automatically using the open-source software Horos v.4.0.0. The distance between the transverse plane passing through the bifurcation point (BP) and the defined planes of the surrounding structures was evaluated. RESULTS: CB was observed below the mastoid process, gonion point, and hyoid bone. CB was observed above the thyroid cartilage. Carotid bifurcation was seen at 15 levels in total, the lowest in the upper 1/3 of the C6 vertebral body and the highest in the lower 1/3 of the C2 vertebral body. In all cases, the most common level was the C3 lower level. CONCLUSION: All these values, which emerged as a result of the study, provide general information about the topography of the CB according to the neighboring structures. Estimating the location of the CB according to the gonion and hyoid bone will give a more accurate result. The vertebral level on the right side increased in direct proportion to age; there was no similar relationship on the left side. It is necessary to be aware of these anatomical variations in order to prevent various iatrogenic complications.

[Congenital cholesteatoma of the mastoid process: cases of diagnosis and surgical treatment]. / Vrozhdennaya kholesteatoma sostsevidnogo otrostka visochnoi kosti: sluchai diagnostiki i khirurgicheskogo lecheniya.

A brief review of the epidemiology and pathogenesis of congenital cholesteatoma (CC) of the temporal bone pyramid is presented, classifications reflecting the degree of spread or localization of the process are considered. Variants of local CCs of the mastoid process don't fit into these classifications, as well as there is no statistics on the frequency of their detection and treatment due to the rarity of this pathology. Clinical cases of diagnosis, surgical treatment of CC of the mastoid process and its results are described. Clinical examples indicate a long-term asymptomatic course of CC of the mastoid process, accompanied by a pronounced destructive process in the mastoid process. Early surgical treatment makes it possible to remove the neoplasm as radically as possible and preserve hearing function.

Experience with three-dimensional exoscope-assisted surgery of giant mastoid process osteoma.

BACKGROUND: The excision of a giant mastoid process osteoma can be challenging. In such situations, the three-dimensional exoscope intra-operative optic may be a promising tool. CASE REPORT: This paper provides a technical description of a giant mastoid osteoma excised under three-dimensional exoscope magnification. A fragmented excision by intralesional curettage was adopted to prevent peri-tumoural damage. This technique had been previously described for the excision of large osteomas of the sinus. CONCLUSION: The three-dimensional exoscope magnification tool had excellent applicability during surgery of a rare mastoid osteoma. In complex anatomical areas, the cavitation and fragmented excision of the tumour may prevent complications and is therefore recommended.

The Radiological Evaluation of the Mastoid Process and Its Implications for Surgical Approaches.

Background and objective In various surgical procedures, in approaching the posterior fossa and the posterolateral cranial base, surface markings are used to locate the groove for transverse and sigmoid sinuses, and their junction. Determining these surface landmarks, especially the mastoid bone and its surrounding anatomical formations, is extremely valuable. The purpose of this study was to examine the anatomical features and the relationship between the mastoid process and surrounding structures on cone-beam CT (CBCT) images. Methods Before starting this retrospective study, approval was obtained from the Ethics Committee of Gaziantep University (approval date: 04/12/2019; number: 470). Individuals who consulted the Department of Oral and Maxillofacial Radiology of Gaziantep University's Faculty of Dentistry between 2015-2018 for any reason and whose CBCT images were taken were included in this study. Frankfort horizontal plane was used for the standardization of the images. Measurements were made on three different sections: coronal, transverse, and sagittal. Results The cohort consisted of 149 females and 98 males; the mean age of the participants was 45.72 ± 17.12 years. It was determined that homogeneity was achieved in terms of data distribution between genders according to age (p=0.777). Additionally, it was determined that there was a statistically significant difference between the genders in all parameters except anterior inclination angle (AIA), and higher values were found in males. Conclusion We believe that the results obtained from this study may contribute toward decreasing the complication rate and increasing success in surgical procedures, especially with respect to approaching the posterior fossa and the posterolateral cranial base.

Mastoid and opisthion-bimastoid triangles for sex determination in a Brazilian sample / Triangulos mastoideo y opistión-bimastoideo para la determinación del sexo en una muestra brasileña

SUMMARY: Human identification involving mutilation, advanced decomposition, and skeletonized materials is a challenge for professionals in forensic medicine and dentistry. This study was aimed at a morphometric analysis of the mastoid and bimastoid triangles to determine sex in a Brazilian population. The sample included 80 human skulls (34 females and 46 males; age: 18 to 60 years) from individuals with death certificates. Linear measurements (mm) of the mastoid process - right (n=3) and left (n=3) - and the opisthion- bimastoid (n=3) triangles were taken (digital caliper) by two previously trained researchers. Three cranial points - asterion, porion and process - were determined for the right and left mastoid triangle and three others - (1) opisthion and (2) right and (3) left mastoid - for the bimastoid triangle. Heron's formula was used to calculate the area of the triangles assessed. Data were submitted to the Shapiro- Wilk normality test, followed by the unpaired Student's t test or the Mann-Whitney U test, depending on the data distribution verified in the normality test (GraphPad Prism 5.01; p<0.05). The ROC curve was used to measure the accuracy of the variables toward sex determination. The opisthion-bimastoid triangle showed high accuracy and significant differences in all the variables assessed and thus was considered a potential element for sex determination in the Brazilian population assessed.

RESUMEN: La identificación humana que comprende la mutilación, descomposición avanzada y materiales esqueletizados, es un desafío para los profesionales de la medicina forense y de la odontología. Este estudio tuvo como objetivo un análisis morfométrico de los triángulos mastoideo y bimastoideo para determinar el sexo en una población brasileña. La muestra incluyó 80 cráneos humanos (34 mujeres y 46 hombres; edad: 18 a 60 años) de sujetos con certificado de defunción. Se tomaron las medidas lineales (mm) del proceso mastoides - derecha (n = 3) e izquierda (n = 3) - y los triángulos opistion-bimastoide (n = 3) (caliper digital) por dos investigadores previamente entrenados. Se determinaron tres puntos craneales - asterion, porion y proceso mastoides - para el triángulo mastoideo derecho e izquierdo y otros tres - (1) opistion y (2) proceso mastoides derecho e izquierdo - para el triángulo bimastoideo. Se utilizó la fórmula de Heron para calcular el área de los triángulos evaluados. Los datos se analizaron con la prueba de normalidad de Shapiro-Wilk, seguida de la prueba t de Student para datos no apareados o la prueba U de Mann-Whitney, según la distribución de datos verificada en la prueba de normalidad (GraphPad Prism 5.01; p <0.05). La curva ROC se utilizó para medir la precisión de las variables hacia la determinación del sexo. El triángulo opistion-bimastoide mostró una alta precisión y diferencias significativas en todas las variables evaluadas, por lo que se consideró un elemento probable para la determinación del sexo en la población brasileña evaluada.

Evaluation of the greater occipital nerve location regarding its relation to intermastoid and external occipital protuberance to mastoid process lines.

BACKGROUND: Localisation of the greater occipital nerve (GON) is essential for the achievement of several procedures performed in the occipital region especially the treatment of occipital neuralgia. This study proposed to investigate the location of GON subcutaneous (Sc) and semispinalis capitis (SSC) piercing points related to the intermastoid and external occipital protuberance (EOP) to mastoid process (MP) lines. MATERIALS AND METHODS: The Sc piercing point, relation to SSC and obliquus capitis inferior (OCI) muscles of 100 GONs from 50 cadaveric heads (23 males, 27 females) were dissected. Distances from EOP to MP (EM line) on both sides and between MPs (MM line) were measured. Perpendicular lines from Sc and SSC piercing points to EM and MM lines were created and measured. Distances from EOP to the perpendicular lines of SSC piercing point and from MP to the perpendicular lines of Sc piercing point were measured and calculated into percentage of EM and MM length, respectively. RESULTS: Three types of Sc piercing points (I, II and III) were obtained. The percentage of GON piercing trapezius muscle (TP) (type I), aponeurosis of TP (type II) and aponeurosis between TP and sternocleidomastoid muscle (SCM) (type III) were 2, 67 and 31, respectively. In addition, 95% of GON pierced SSC, 2% pierced its tendinous band and 3% travelled between its medial fibres and the nuchal ligament. 94% of the GON turned around the lower edge of the OCI, while 6% pierced the lower edge of this muscle. Sc piercing point was always located above the MM line, but it could be above, below or on the EM line. In contrast, all of the SSC piercing points were located below the EM line except in one specimen, but it could be above, below or on the MM line. Therefore, the MM and EM lines were used as reference lines for locating the Sc and SSC piercing points, respectively. The mean EM line length was 81.26 ± 5.26 mm with statistically significant differences between genders and sides in female. The mean MM line length was 121.77 ± 8.54 mm with a statistically significant difference between genders. Sc piercing point could be located at 44% of MM line length from ipsilateral MP with a mean vertical distance of 18 mm. No statistically significant difference was found between genders and sides in these parameters, but a statistically significant difference was found in the percentage of MB to MM line between type III and type I (p = 0.02). SSC piercing point of all types could be located at the point of 25% of EM line length from EOP with a vertical distance of 18 mm below EM line. No statistically significant difference was found between genders, sides and types of both piercing points. CONCLUSIONS: MM and EM lines are potential reference lines for locating the Sc and SSC piercing points of GON, respectively.

Newer injection points for facial contouring with hyaluronic acid filler-Case Report.

BACKGROUND: Hyaluronic fillers have been used for filling in folds and contour the face according to global aesthetic standards to achieve a smooth ogee curve on the face. But sometimes these result in a bulkier look to the face thus preventing more people from opting for these procedures. Although M.D codes have now been given to guide the injecting physicians for various points of injections on the face, they need to be used judiciously and tailored to individuals, using the lateral points of the face first. AIMS: Patients still come to physicians to get the midface and nasolabial folds corrected but a proper aesthetic evaluation is essential and it was observed that targeting the peripheral points of the face leads to better tightening of the face and a slimmer look for the patient. A case was injected on peripheral points including some newer points not mentioned in the M.D codes. These points are on the forehead along the hairline and the mastoid process. Safety and efficacy of injecting on these particular points were evaluated. METHODS: 2-ml hyaluronic acid syringes (20 mg conc) were used to give bolus injections on the peripheral points of the face, including a new point on mastoid process and peripheral points on forehead. RESULTS: A good aesthetic outcome was achieved resulting in slimming of face with patient satisfaction and without any complications. CONCLUSION: A good nonsurgical contouring of a young face can be achieved with 2 ml hyaluronic acid injection when the correct points are injected.

Sex determination by osteometric assessment of the mastoid process using Cone Beam Computed Tomography / Determinação do sexo em uma população Iraniana por avaliação osteométrica do processo mastóide em imagens de TCFC

Objective: Sex determination is one of the most important parameters to identify in forensic science. Because the mastoid process is the most resistant to damage due to its position in the skull base, it can be used for sex determination. The purpose of this study was to measure the dimensions and convexity and internal angles of the mastoid process to present a model of sex determination in Iranian population. Material and methods: This study was performed on three-dimensional images of 190 Cone Beam Computed Tomography (CBCT) of 105 women and 85 men. On each CBCT the distance between the porion and the mastoid (PM), mastoid length (ML), the distance between the mastoidale and the mastoid incision (M-I), the mastoid height (MH), the mastoid width (MW), intermastoidale distance (IMD) the lateral surfaces of the left and right mastoids (IMLSD) and the Mastoid medial convergence angle (MMCA) was measured on both the right and the left. The data were analyzed by descriptive statistics, t-test, and discriminant function analysis. Results: Significant differences were found for all variables except MMCA and MF in both sex. All measured variables except MW were greater for men than women. The discriminant model achieved a total accuracy of 93.7%. Among the measured factors IMD and IMSLD had the most influence on sex determination. Conclusion: Measuring the dimensions of the mastoid process is a very good method for sex determination with high accuracy of 90% (AU)

Objetivo: A determinação do sexo é um dos parâmetros mais importantes para identificação na ciência forense. Por ser o processo mastóide resistente a danos, devido a sua posição na base do crânio, este poderia ser usado na determinação do sexo. O objetivo deste estudo foi mensurar as dimensões, convexidade e ângulos internos do processo mastóide para apresentar um modelo de determinação do sexo em uma população Iraniana. Material e métodos: Este estudo foi realizado em 190 imagens de tomografia computadorizada de feixe cônico (TCFC), sendo 105 mulheres e 85 homens. Em cada TCFC foram realizadas medidas no processo mastóide em comprimento (ML), altura (MH), largura (MW) em ambos os lados direito e esquerdo, também foi medida a distância entre o Pórion e o processo mastóide (PM), distância até incisura mastoidea (M-I), distância entre as superfícies mediais (IMD) distância entre as superfícies laterais dos processos direito e esquerdo (IMLSD) e o ângulo de convergência medial (MMCA). Os dados foram analisados por estatística descritiva, teste t e análise de função discriminante. Resultados: Diferenças significativas foram encontradas para todas as variáveis, exceto MMCA e MF em ambos os sexos. Todas as variáveis medidas, exceto MW, foram maiores para os homens do que para as mulheres. O modelo de análise de função discriminante alcançou uma precisão total de 93,7%. Entre os fatores medidos, o IMD e o IMSLD tiveram a maior influência na determinação do sexo. Conclusão: Podemos concluir que as dimensões do processo mastóide constituem um método para determinação do sexo, em população Iraniana, com precisão de 90% (AU)

[The infracochlear approach for diagnostic petrous apicotomy]. / Der infracochleäre Zugang zur Felsenbeinspitze aus diagnostischer Indikation.

Diagnostic and therapeutic approaches to the petrous apex involve sub-/transtemporal, retrosigmoidal, infratemporal and-lesser invasive-e. g. infracochlear, infralabyrinthine or under favourable anatomic conditions, transsphenoidal surgical pathways. For diagnostic purposes, minimally invasive approaches should be preferred due to their lesser morbidity. This article illustrates the infracochlear approach to the petrous apex in the case of a diagnostic indication in a patient with an incidental, asymptomatic tumorous lesion of the right petrous apex with bony erosion. After the bone of the floor of the ear canal and the hypotympanum was removed, the carotid artery and the jugular bulb were identified using a diamond burr. The route to the petrous apex is triangled by the cochlea superiorly, the jugular bulb posteriorly, and the carotid artery anteriorly. After opening the petrous apex lesion, biopsies were taken. The defect in the floor of the ear canal and the hypotympanum was reconstructed with cartilage and temporalis fascia. The patient recovered quickly from surgery without vertigo or hearing loss. Histological evaluation showed a chondrosarcoma. The patient opted for primary radiation therapy (C12, 63 Gy). The infracochlear approach is minimally invasive and can offer access to the petrous apex with minimal morbidity. The pathway, however, is narrow and deep and bounded by the jugular bulb and the carotid artery. The available space can be estimated from preoperative CT scans and, if possible, with 3D reconstructions. Navigation can additionally enhance safety.

A new method for tracing the facial nerve trunk using the posterior auricular nerve.

Tracing the facial nerve trunk is an essential action in parotid surgery, because of the implications of injury to the nerve or its branches. More than a few landmarks that may help the surgeon in this task have been proposed (e.g., the posterior belly of the digastric muscle, the tragal pointer, among others), under the assumption that additional access methods improve the surgical technique and reduce the possibility of harmful post-operative consequences. Here we present evidence that the posterior auricular nerve may be used to trace the facial nerve trunk. We dissected 75 cadaveric heminecks, exposed the auricularis posterior muscle and adnexa, and attempted to follow the posterior auricular nerve to the facial nerve trunk. The auricularis posterior muscle, nerve, and artery were identified in all heminecks, securing an anatomically reliable route to the facial nerve trunk. Average length of the nerve from the auricularis posterior muscle to the facial nerve trunk was 28 mm (±6.2 mm). The angle between the posterior auricular nerve and the vertical segment of the FN trunk was 39.5° (±7.7°). We conclude that the posterior auricular nerve may be used as a landmark to trace the facial nerve trunk. It is advantageous due to the relatively simple and consistent regional anatomy, and also because manipulation of this nerve does not present a risk given that the auricularis posterior muscle is vestigial. The proposed landmark is particularly important in revision surgery, where the pre-auricular anatomy may have been distorted and scarred by previous operations. Clin. Anat. 32:453-457, 2019. © 2019 Wiley Periodicals, Inc.

Quantitative Sex Estimation Based on Cranial Traits Using R Functions.

This paper presents an R script that quantifies the shape of selected cranial traits and automates sex estimation. The proposed functions were tested on two modern Greek assemblages. The discriminant variables input in the functions are calculated from a digital photograph of the lateral view of the cranium. The cranial outline is determined using the Canny edge detector and discriminant variables that quantify the shape of the glabella/frontal bone, mastoid process, and external occipital protuberance are computed. The best cross-validated results for pooled sexes in the Athens Collection range from 84.2% to 87.3%, and increase up to 93.9% when half of the sample is used for training and the rest for prediction, while correct classification for the Cretan material is 80-90% for optimum combinations of discriminant variables. The greatest advantage of the proposed method is its straightforward and time-efficient application.

Anterior Greater Auricular Point: Novel Anatomic Landmark to Facilitate Harvesting of the Greater Auricular Nerve.

BACKGROUND: The greater auricular nerve (GAN) may be used as a nerve graft during neurosurgical procedures to repair damaged nerves. There is extensive literature on localization of the GAN at the posterior triangle of the neck, but objective information on localization of the GAN at the anterior triangle of the neck close to cranial neurosurgical fields is lacking. The aim of this study was to introduce simple and reliable landmarks to localize the GAN at the anterior triangle of the neck to facilitate its harvest during neurosurgical procedures. METHODS: The GAN was exposed bilaterally in 11 cadaveric specimens at the point of crossing the anterior border of the sternocleidomastoid muscle (anterior greater auricular point [AGA]). Distances from the AGA point to the angle of the mandible and the tip of the mastoid process were measured. Additionally, the location of the crossing point between the GAN and an imaginary line passing through the mastoid tip and the angle of the mandible (M-A line) was found relative to these bony landmarks. RESULTS: Mean (±SD) distances from the AGA point to the mastoid tip and the angle of the mandible were 29.1 ± 3.4 mm and 27.5 ± 4.5 mm, respectively. The GAN was always found to cross the M-A line in its middle third (mean 48.2% ± 6.9% from the mastoid tip). CONCLUSIONS: The AGA point and the M-A line are reliable landmarks for locating the GAN at the anterior triangle of the neck and for helping neurosurgeons expose and harvest the GAN efficiently.

[Vascularized tumor of the retroauricular skin]. / Gefäßreicher Tumor der retroaurikulären Haut.

An 84-year-old female patient with loss of hearing and otorrhoea went to an otolaryngologist. On examination, a polypoid mass in the auditory canal and a retroauricular skin lesion, possibly seborrheic keratosis, were found. Only the skin was submitted for histological examination and showed a cutaneous highly vascular lesion with an associated "zellballen" of clear cells without atypia. The initial diagnosis was that of a cutaneous glomangioma. Immunohistochemical findings favored diagnosis of a paraganglioma. Additional clinical information revealed a large mastoid tumor mass. Therefore, the findings were compatible with an jugulotympanic paraganglioma with infiltration of the overlying skin. This possibility was initially not considered in differential diagnosis, as cutaneous glomangiomas are relatively common (typically located on the hands). Cutaneous paragangliomas, however, are not reported.

A quantitative approach for sex estimation based on cranial morphology.

OBJECTIVES: This paper proposes a method for the quantification of the shape of sexually dimorphic cranial traits, namely the glabella, mastoid process and external occipital protuberance. MATERIALS AND METHODS: The proposed method was developed using 165 crania from the documented Athens Collection and tested on 20 Cretan crania. It is based on digital photographs of the lateral view of the cranium, drawing of the profile of three sexually dimorphic structures and calculation of variables that express the shape of these structures. RESULTS: The combinations of variables that provide optimum discrimination between sexes are identified by means of binary logistic regression and discriminant analysis. The best cross-validated results are obtained when variables from all three structures are combined and range from 75.8 to 85.1% and 81.1 to 94.6% for males and females, respectively. The success rate is 86.3-94.1% for males and 83.9-93.5% for females when half of the sample is used for training and the rest for prediction. Correct classification for the Cretan material based upon the standards developed for the Athens sample was 80-90% for the optimum combinations of discriminant variables. DISCUSSION: The proposed method provides an effective way to capture quantitatively the shape of sexually dimorphic cranial structures; it gives more accurate results relative to other existing methods and it does not require specialized equipment. Equations for sex estimation based on combinations of variables are provided, along with instructions on how to use the method and Excel macros for calculation of discriminant variables with automated implementation of the optimum equations.

Evaluation of Mastoid Process as Sex Indicator in Modern White Americans using Geometric Morphometrics.

Conventional methods for evaluating the mastoid as a sex indicator cannot determine whether mastoid shape is an independent and reliable sex indicator. Here, shape differences between the mastoids of 100 male and 100 female modern white Americans were statistically analyzed and visualized using the geometric morphometric method. Discriminant analysis was performed on mastoid size and shape. The relation between size and shape was analyzed to examine the effect of size on shape. In the results, mastoid size and shape were statistically significant sex indicators, while size factor explained 87.3% of the total variance of the shape variables. Nevertheless, females had relatively broader and shorter mastoid shape than males regardless of size, reflecting 12.7% of the total variance of the shape variables. In conclusion, mastoid size and shape were statistically significant sex indicators, while size may matter more in the mastoid than in other cranial parts in terms of sexual dimorphism.

Prevalence of Zygomatic Air Cell Defect using Orthopantomogram.

AIM: To determine the prevalence, radiographic appearance, variations, characteristics and establishing dominant location and type of zygomatic air cell defect (ZACD) among the North Indian population. MATERIALS AND METHODS: The panoramic radiographs of 2500 dental clinic outpatients were examined for the presence of ZACD for estimating the prevalence and characteristics of the ZACD. RESULTS: ZACD was found in 63 patients with a prevalence of 2.5% with male predominance. Unilateral (70%) and unilocular appearance (78%) of ZACD were the dominant patterns. Patients with ZACD had a mean age of 37.4 years and a range of 19-78 years. CONCLUSION: The prevalence of ZACD among the Indian population is in accordance with the other studies carried out in other populations of the world. So it is important for surgeons to assess location of ZACD before planning any surgical procedure in order to avoid intraoperative complications.

The Human Shoulder Suspension Apparatus: A Causal Explanation for Bilateral Asymmetry and a Fresh Look at the Evolution of Human Bipedality.

The combination of large mastoid processes and clavicles is unique to humans, but the biomechanical and evolutionary significance of their special configuration is poorly understood. As part of the newly conceptualized shoulder suspension apparatus, the mastoid processes and clavicles are shaped by forces exerted by the musculo-fascial components of the cleidomastoid and clavotrapezius muscles as they suspend the shoulders from the head. Because both skeletal elements develop during infancy in tandem with the attainment of an upright posture, increased manual dexterity, and the capacity for walking, we hypothesized that the same forces would have shaped them as the shoulder suspension apparatus evolved in ancestral humans in tandem with an upright posture, increased manual dexterity, and bipedality with swinging arms. Because the shoulder suspension apparatus is subjected to asymmetrical forces from handedness, we predicted that its skeletal features would grow asymmetrically. We used this prediction to test our hypothesis in a natural experiment to correlate the size of the skeletal features with the forces exerted on them. We (1) measured biomechanically relevant bony features within the shoulder suspension apparatus in 101 male human specimens (62 of known handedness); and (2) modeled and analyzed the forces within the shoulder suspension apparatus from X-ray CT data. We identified eight right-handed characters and demonstrated the causal relationship between these right-handed characters and the magnitude and direction of forces acting on them. Our data suggest that the presence of the shoulder suspension apparatus in humans was a necessary precondition for human bipedality.