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Test of age-related variation in the craniometry of the adult human foramen magnum region: Implications for sex determination methods

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Test of age-related variation in the craniometry of the adult human foramen magnum region: Implications for sex determination methods

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Abstract

Sex differences in the foramen magnum region of the cranial base have been identified with varying rates of success. Recent publications demonstrate a continuing strong interest in metric analysis of the foramen magnum region for sex determination despite the generally low expression of cranial base sexual dimorphism. It is important to identify possible age effects on skull base morphometric variables as most reported discriminant analyses use pooled-age samples without assessing the influence of aging on sexual dimorphism. This study examined 135 adult cranial bases (69 males and 66 females) from the St. Bride's documented skeletal collection in London. Traditional craniometric measurements were recorded and the effect of age on sexual dimorphism of this anatomical region was tested using a variety of statistical analyses including MANOVA and discriminant function analysis. Age-dependent discriminant functions for <50 and >50 years of age were developed and compared. The cross-validated results showed that the <50 years function determined the sex of 69.1 % correctly while the >50 years function achieved 81.3 % correct predictions. However, the high sex biases of these functions (14.4 % and -17.5 %) severely limit their practical application. A pooled-age discriminant function permitted 71.9 % correct prediction with a sex bias of only -1.7 %. The statistical analyses also showed no significant age effect on any of the variables, suggesting that a separation by age is not necessary for the development of sex determination methods.

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... [13] The CT scan images can be used in sex determination research because of easier access to a large documented sample, data easily shared to other researchers and provides several reliable measurements without fleshy barriers. [14] Previous studies were widely done on European [15][16][17], American [18] South American [19][20][21], Libyan, [22], Turkish [23][24][25], Egyptian [26,27], Iraqi [28], Iranian [29] Sudanese [30] Indian [31][32][33][34] and Nepalese population [35]. To date, very little researches have been was conducted on the Saudi Arabian population [36]. ...
... Eight variables were recorded according to the definitions provided by Gapert et al. [15,16]. The maximum length of the FM (FML) in the midsagittal plane (basion to opisthion) and the maximum width of the FM (FMW) were recorded at the widest transverse diameter between the lateral margins measured approximately perpendicular to principle axis of the foramen (Fig. 2). ...
... The cartilage of the skull base resists the compression. The atlanto-occipital joint is mostly under static stress and sexual changes due to compressive loading of the occipital condyles may therefore be minimal [15,16]. ...
Objective of the study The objective of this study was to evaluate FM and occipital condyles measurements morphometrically for sex determination by using discriminant function analysis and to note visually the variation in the shape of the foramen magnum in a Saudi Arabian population by using CT scan images. Material and methods This study included 472 CT scans (236 males and 236 females; age range, 18–72 years). The foramen magnum shapes were classified into 8 types: oval, egg, round, hexagonal, pentagonal, tetragonal, irregular (A) and irregular (B). The intraobserver and interobserver test was done to calculate the reliability of the measurement. Eight dimensions of the FM and occipital condyle were evaluated to determine the sexual dimorphism using an independent t-test. Sex determination was estimated using discriminate function analysis. Results The commonest shape of FM was hexagonal and the tetragonal shape was the least common type. Coefficient of reliability (R) was high, ranging between 0.89 and 0.99, which indicates the measurements are reliable and sufficiently precise. All the eight measurements, the FM length and width, FM index, FM area, the width and length of right and left occipital condyles were significantly greater in males than the female. Univariate discriminant function showed an accuracy rate varying from 61% to 66.6% based on FM or occipital condyles measurements. The multivariate analysis of FM and occipital condyle measurements increased the overall accuracy rate of sex determination to 71.6%. Conclusion The univariate analysis of FM and occipital condyle measurements indicates, that the FM area (66.1%), FML (62.5%), FMW (62.5%) and ROCL (62.1%) could be reliable individual variables in sex determination. The multivariate analysis including all the eight variables of FM and occipital condyle increased the accuracy rate of sex determination to 71.6% in determining the sex as male (73.3%) or female (69.9%). The shape of the FM is not useful in sex estimation. The results obtained showed a low degree of sexual dimorphism in the basicranium, the use of this method in forensic anthropology could be helpful for assessment on highly fragmented skull bases.
... Sex estimation accuracy rates of between 58.8 % and 90.9 % have been reported when only foramen magnum measurements were used ( Table 1). In some studies, using occipital condyle measurements together with foramen magnum measurements has provided some improvements in sex estimation accuracy, with accuracy rates reaching 94.0 % [10][11][12][13][14][15][16]18,20,[30][31][32][33][34][35]44] (Table 1). In addition, one study claimed that sex estimation could be made with an accuracy rate of 96 % using only foramen magnum measurements [8]. ...
... While some studies have used univariate analysis only [8,9,21,38], others have used multivariate sex estimation techniques, such as Discriminant Function Analysis (DFA) [4,7,8,10,11,14,15,[17][18][19]24,[26][27][28][29][30][33][34][35][36][37][39][40][41][42][43][44] or regression analysis [4,12,13,16,20,22,23,25,31,32]. Although Artificial Neural Networks (ANN), a newly emerging classification technique, has been used in sex estimation studies on some other bones [45][46][47][48][49][50][51], there is currently no study where it has been used on the foramen magnum. ...
Article
Background: Although many studies have been conducted using the foramen magnum for sex estimation, recent findings have indicated that the discriminant and regression models obtained from the foramen magnum may not be reliable. Artificial Neural Networks, was used as a classification technique in sex estimation studies on some other bones, did not used in sex estimation studies on the foramen magnum until now. The aim of this study was sex estimation on an Eastern Turkish population sample using foramen magnum measurements, discriminant analyses and Artificial Neural Networks. Methodology: The study was performed on the CT images of a total of 720 cases, comprising 360 males and 360 females. For sex estimation, discriminant analysis and Artificial Neural Networks were used. Results: The accuracy rate was 86.7% with discriminant analysis and when sex estimation accuracy was determined according to cases with posterior probabilities above 95%, the accuracy ranged from 0% to 33.3%. With the use of the discriminant formulas of 2 other studies, obtained from different Turkish samples, sex could be determined at a rate of 84.6%. Some formulas were found to be unsuccessful in sex estimation. Sex estimation accuracy of 88.2% was achieved with Artificial Neural Networks. Conclusion: In this study, it was found that sex could be determined to some extent with discriminant formulas from other samples from the same population, although some formulas were unsuccessful. With the use of image processing techniques and machine learning algorithms, better results can be obtained in sex estimation.
... D'autres études ont observé une amélioration de la classification sexuelle à partir de 40 ans, tant pour le crâne (Nikita, 2014) que pour la mandibule (Gillet et al., 2020). Pour Gapert et al., le degré de précision de l'estimation sexuelle à partir du foramen magnum augmentait après 50 ans, en particulier pour les femmes (Gapert et al., 2013). Néanmoins, la majorité de ces études se base sur des méthodes métriques, et prend surtout en compte le dimorphisme sexuel de taille plutôt que de celui de conformation. ...
... descriptives) et quantitatives (métriques et morphogéométriques). Il semblerait qu'une augmentation de la précision de classification du sexe à partir du crâne et de la mandibule peut être observée avec le vieillissement, et que ces changements commencent à être décelables entre 40 et 50 ans(Gapert et al., 2013;Gillet et al., 2020;Nikita, 2014;Suazo & Matamala, 2012). Bien que le vieillissement de certains traits du squelette et des tissus mous faciaux ait été étudié, en particulier dans le domaine de la chirurgie plastique et de reconstruction(Cotofana et al., 2018;Robertson et al., 2017), l'impact des changements dus au vieillissement et à la perte dentaire sur le dimorphisme de conformation mandibulaire reste peu exploré. ...
Thesis
La mandibule est un os du massif facial aux caractères dimorphiques très marqués, pouvant être employé dans l'estimation du sexe d'un individu. Étant le seul os mobile de l'extrémité céphalique, elle peut être séparée du crâne dans des contextes archéologiques ou médico-légaux. Par ailleurs, il s'agit d'un os soumis à des phénomènes de remodelage osseux de par la perte dentaire et les contraintes mécaniques qu'il subit au cours de la fonction masticatoire. L'objectif de ce travail était, d'une part, d'améliorer la performance des techniques d'estimation sexuelle à partir de la mandibule et, d'autre part, d'avoir une meilleure compréhension des changements morphologiques que subit cette structure au cours du vieillissement. Dans un premier temps, nous avons étudié le rôle de la mandibule dans le dimorphisme sexuel de l'extrémité céphalique. Des méthodes métriques et morpho géométriques, basées sur le positionnement informatique de landmarks, ont été employées sur 120 examens tomodensitométriques d'individus âgés de 23 à 84 ans. Nos résultats ont montré que la morphométrie géométrique offre une précision de diagnose sexuelle supérieure à la méthode métrique traditionnelle. Par ailleurs, le crâne présente une plus grande précision d'estimation sexuelle que la mandibule, quelle que soit la méthode d'analyse employée. Enfin, le taux de prédiction correcte du modèle mandibulaire s'améliore à partir de 40 ans. Dans un deuxième temps, nous avons analysé l'effet du vieillissement et de la perte dentaire sur la conformation mandibulaire, ainsi que l'impact de ces changements morphologiques sur l'identification du sexe d'un individu. 14 landmarks mandibulaires ont été placés sur 160 examens tomodensitométriques de sujets âgés de 40 à 79 ans. Nos analyses par morphométrie géométrique montrent que le dimorphisme sexuel mandibulaire demeure significatif avec le vieillissement et que les changements de conformation mandibulaire débutent à 50 ans. En revanche, la sénescence affecte différemment les individus masculins et féminins : le processus semble être plus précoce, plus rapide et plus accentué chez la femme, et les changements de conformation touchent des zones différentes selon le sexe. Par ailleurs, l'édentement, en particulier la perte de calage dentaire, entraîne des modifications de conformation différentes entre hommes et femmes. Il tend ainsi à estomper le dimorphisme sexuel de taille et à accentuer le dimorphisme sexuel de conformation.
... It is quite possible that postmenopausal females develop more masculine cranial features [53,54], while young males show more gracile and feminine cranial features [53]. Some authors recommended that sex estimates may only be accurate within a certain age range [30], as for instance 25-55 years [48], or even below 50 years [55] because of the coarser granulation of the bone surface, the bone resorption associated with tooth loss, and the vault structure changes due to reduced masticatory muscle stress. However, as reported by Manthey et al., a better understanding of European SD is needed [24]. ...
... These changes in cranial variables in the elderly were confirmed in previous research [66] and may affect the results of sex determination; however, it is not necessary to design agedependent classification tools [55]. The possible tendency to the masculinization of female skulls with aging might have caused a difficulty in discriminating between the sexes using the traditional visual and metric tools [67]. ...
Article
Full-text available
Biomechanical load and hormonal levels tended to change just like the soft and skeletal tissue of the elderly with age. Although aging in both sexes shared common traits, it was assumed that there would be a reduction of sexual dimorphism in aged individuals. The main goals of this study were (1) to evaluate age-related differences in cranial sexual dimorphism during senescence, (2) to determine age-related differences in female and male skulls separately, and (3) to compare skull senescence in Czech and French adult samples as discussed by Musilová et al. (Forensic Sci Int 269:70–77, 2016). The cranial surface was analyzed using coherent point drift-dense correspondence analysis. The study sample consisted of 245 CT scans of heads from recent Czech (83 males and 59 females) and French (52 males and 51 females) individuals. Virtual scans in the age range from 18 to 92 years were analyzed using geometric morphometrics. The cranial form was significantly greater in males in all age categories. After size normalization, sexual dimorphism of the frontal, occipital, and zygomatic regions tended to diminish in the elderly. Its development during aging was caused by morphological changes in both female and male skulls but secular changes must also be taken into account. The most notable aging changes were the widening of the neurocranium and the retrusion of the face, including the forehead, especially after the age of 60 in both sexes. Sexual dimorphism was similar between the Czech and French samples but its age-related differences were partially different because of the population specificity. Cranial senescence was found to degrade the accuracy of sex classification (92–94%) in the range of 2–3%.
... Recently, there has been an increase in the number of publications on sexing methods based on fragmentary remains of the basicranium. These methods use, for example, the maximum transverse diameter [11] together with the antero-posterior diameter of foramen magnum (FM) [12][13][14][15], some others add the area of FM [16], its circumference [17], and dimensions of occipital condyles [13,15,18,19]. Table 1 provides basic overview of these methods together with their accuracy. ...
... When evaluating the foramen magnum, the issue of individual's age seems not to be of major concern, as Gapert et al. [18] or Coquegniot and Le Minor [85] have already shown that there are no significant changes in its dimensions during one's life once the ossification of this area in early childhood is completed. ...
Article
Sex assessment of skeletal remains in the context of forensic investigation is one of the most important components when constructing biological profile of the deceased individual since it helps to significantly narrow down the number of potential victims. Therefore, the number of methods suitable to estimate sex should be as wide as possible, especially for cases of highly fragmented remains. This paper offers a classification method for sexing human remains based on an area around foramen magnum and tests other similar discriminatory functions published elsewhere on an independent sample from the circummediterranean region. We provide discriminant and logistic regression functions for several sets of variable combinations derived from head CT images. None of the functions performs reliably enough to be used in the forensic context. The same holds true for other discriminatory functions published in the literature. For most of the functions, the failure rate (its inability to successfully assign sex of an unknown individual) reaches 100%. Thus, despite the fact that foramen magnum is sexually dimorphic in most populations, its use in sexing cranial remains in the forensic context should be limited only to cases in which we know population affinity of unknown skeletal remains and can provide referential data from the same population to estimate sex.
... However, most authors connect the sexual dimorphism with the evaluated structure to bone changes. Such topic is extensively revised in recently published paper by Gapert et al. [34]. ...
... Bootstrapping of 1000 samples was carried out on the comparisons between the Rainer, Georges Olivier, and Middenbeemster samples to control for the unequal sample sizes. As age and head/body size have been shown to not correlate with basal dimensions (Gapert et al. 2013;Guidotti 1984;Naderi et al. 2005;Wescott and Moore-Jansen 2001), they were not tested in the present paper. ...
Article
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Multiple discriminant functions that estimate sex from the dimensions of the basal occipital have been published. However, as there is limited exploration of basal dimension variation between groups, the accuracy of these functions when applied to archaeological material is unknown. This study compares basal dimensions between four known sex-at-death post-medieval European samples and explores how metric differences impact on the accuracy of sex assessment discriminant functions. Published data from St Bride’s, London (n = 146) and the Georges Olivier collection, Paris (n = 68) were compared with new data from the eighteenth to nineteenth century Dutch Middenbeemster sample (n = 74) and the early twentieth century Rainer sample, Romania (n = 282) using independent t tests. The Middenbeemster and Rainer data were substituted into six published discriminant functions derived from the St Bride’s and the Georges Olivier samples, and the results were compared to their known sex. Multiple statistically significant differences were found between the four groups. Of the six discriminant functions tested, five failed to reach the published accuracy and fell below chance. In addition, even where the samples were statistically comparable in means, trends for difference also impacted the accuracy of discriminant functions. Enough variation in basal occipital dimensions existed in the European groups to decrease the accuracy of sex estimation discriminant functions to unusable. Possible inter-observer error, varying genetic, socioeconomic, and geographical factors are likely causes of dimension variation. This research further highlights the dangers of using sex estimation discriminant functions on samples that differ to the original derivative population and demonstrates the need for more rigorous testing.
... The contributions of classical cranial anthropometry to the study of the evolutionary scenarios of hominin cranial shapes and sizes have been well demonstrated, and in archaeological and forensic anthropology, measures and indices are still commonly used to reconstruct a biological profile of an individual (e.g., Kimbel and Rak, 2010;Gapert et al, 2013;Veroni et al., 2010;Gonzalez, 2012). At the same time, metrics are usually employed in dental anthropology for sex determination (Viciano et al., 2015) and estimation of age (Irurita et al., 2014). ...
Article
Full-text available
Cranial and dental anthropometry is commonly used in many areas of research, e.g., in forensic anthropology and paleoanthropology. We propose new craniometric and dental landmarks and distances that may have important applications in physical anthropology. Furthermore, a classical anthropometrical approach was applied to quantify the correlation between dental and cranial measurements, which were taken on 30 Middle Ages adult crania from Sardinia (Italy). Principal components analysis was performed to explore the correlations among inter-landmark distances. The first component showed correlations between the cranial base and maxillary inter-landmark distances (the ‘cranial base’ sytem). The second component exclusively demonstrated correlations among maxillary and dental inter-landmark distances (the ‘oral cavity’ system). The third component showed positive correlations between the zygomatic and midline maxillary inter-landmark distances, and high negative loadings that include the bilateral styloid process and midline maxillary landmarks (the ‘upper cranium’ system). The inter-landmark dental distances correlate with inter-landmark cranial distances that have not been described previously. These data can be applied in other research and clinical areas.
... After puberty, age does not affect the size of the foramen magnum. Therefore, differences in the results of various studies could not be due to the age of the samples and there is no need to consider age while determining sex based on the dimensions of the foramen magnum (21). In addition, this could be an advantage in using the foramen magnum. ...
Article
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Background: Foramen magnum is a big hole in the base of the skull. Its appearance can be useful in gender determination. So far, no study has been conducted in Iran that evaluates the value of foramen magnum in sex determination and calculates the cutoff points. This study aimed to evaluating of diagnostic value of the foramen magnum and to calculate the cutoff points for sex determination. Methods: In this cross sectional study 50 male and 50 female patients referring to the radiology department of Rasol Akram Hospital in Tehran were evaluated. The required information about the sagittal diameter, transverse diameter, and diameter of foramen magnum were assessed by brain CT scan. Chi-square and independent t test was used for the comparison of different shapes and diameters between the sexes. ROC curve was used to determine the optimal cutoff point for each indicator. Results: The best cutoff point to distinguish males from females along the anterior-posterior foramen magnum was calculated as 36.45 mm, at the transverse diameter of 30.4 mm. The proper cutoff points for the area of the foramen magnum were 877.477 mm 2 and 870.29 mm 2 , based on the Teixeria formula and Routal formula respectively. Overall, the accuracy of these indicators was calculated as 85%. Conclusion: Based on the results of this study using CT scans images, the diameter of the foramen magnum and its area had a high accuracy in sex determination. Copyright©2016 Forensic Medicine and Toxicology Department. All rights reserved.
... The correlation coefficient (R value) was found to be weaker (R=0.0413 26,27 Age does not affect the size of the foramen magnum after puberty. Therefore, differences in the results of various studies could not be due to the age of the samples. ...
Article
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p class="abstract"> Background: Radiological determination of gender relies predominantly on the skeletal radiology and assumes importance in mass natural disasters, bomb explosions, exhumations and warfare where skeletal fragmentation is common. Varied literature is present regarding the role of foramen magnum in establishing gender identification. The objective of the study was to establish normative values of cross-sectional area of foramen magnum in both genders using NCCT and try to ascertain any significant difference in cross-sectional area in the two genders which may help in gender identification. Methods: NCCT head images of 378 subjects were analysed in individuals beyond the age of skeletal immaturity. Free ROI technique using electronic calliper tool was used. The cross-sectional area of foramen magnum was automatically obtained after tracing its whole inner circumference. Results: Mean cross-sectional area of foramen magnum in females was 806.79±106.58 mm<sup>2 </sup>and was 878.33±98.42 mm<sup>2</sup> in males. Although the cross-sectional area in males was greater than females no statistically significant difference was found. The correlation coefficient was found to be weaker (R=0.0413). Conclusions: No statistically significant difference was found between the two genders. The correlation coefficient was also weak to draw any inference about the gender of the skull on CT imaging. Further studies are needed to include other parameters like the sagittal and transverse diameters of foramen magnum in a larger sample to show importance of foramen magnum, if any, in helping gender identification of skeletal remains. </p
... Therefore, differences in the results of various studies could not be due to the age of the samples and there is no need to consider age while determining gender based on the dimensions of the FM. 35 The degree of expression of sexual dimorphism within the FM dimensions may be explained by its development. Compared with many other skeletal elements, the FM reaches its adult size rather early in childhood and is unlikely to respond to significant secondary sexual changes. ...
Article
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Introduction The successful identification of the deceased is vital to the progress of any forensic investigation. This process of identification is facilitated by the determination of age, gender, and ethnicity. One of the main biological traits to be established from skeletal remains is the gender of the individual. In situations in which there are fragmented and mutilated skeletal remains, gender determination is relatively difficult, and it becomes important to establish the accuracy of individual bones. The basal region of the occipital bone is covered by a large volume of soft tissue and is therefore in a relatively well-protected anatomical position and, as such, classification of gender using the occipital bone may prove to be useful in cases of significantly disrupted remains. The present study aims to describe and analyze the morphological aspects of the foramen magnum (FM) in the population of the northeastern region of Brazil. Material and Methods A total of 159 dry skulls (88 males and 71 females) were subjected to measurement by a digital caliper (DIGIMESS®, Instrumentos de Precisão Ltda., São Paulo, Brazil) and was assessed for anteroposterior diameter (APD) and transverse diameter (TD), FM area, FM index (FMI), anterior, posterior and maximum lateral intercondylar distance. The measurement of all of these parameters sought to classify the FM in nine different types. Results The pentagonal type was the most found in males (11.31%), and the biconvex in females (18.86%). The less frequent type in males was the pear type (2.53%), and in females the less frequent types were the pentagonal and the heptagonal types (2.53% each). Using the traditional anthropological classification of Martin et al,13 the most common type of FM was the brachytrematous, with 49.68% of the total skulls. The APD, TD and FM area were higher in males than in females, only in the oval FM type. Conclusion The sexual dimorphism of the dimensions of the FM is established. However, there is a wide variability in the shape and measures in different populations, and to our knowledge this is the first study that shows the different types of the FM in the population of the northeastern region of Brazil.
... Recently, with the use of imaging techniques, such as CT or laser scanning, capable of generating digital 3D models of human crania, many new possibilities have opened up for anthropological researchers and practitioners, alike. Some studies have, for example, investigated the utility of craniometric analysis of the mastoid triangle [7], the foramen magnum [8,9], the course of the internal acoustic meatus [10], the frontal [11] and temporal bone [12], or the zygomatic bone [13] for sex determination. Such newly established metric methods and parameters for the evaluation of sexually dimorphic cranial features are predominantly used in anthropological and forensic practice in cases where only incomplete crania, or cranial fragments, are available, while the "traditional" methods, which rely on the morphognostic assessment of the most salient cranial features (e.g., glabellar prominence, mastoid processes, zygomatic processes, or nuchal plane) [5], still find application when whole or mainly intact skulls are available. ...
Article
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In sex determination from crania, a “vertical” forehead is considered a female feature, while a “sloping” forehead is considered a male feature. Precise description of frontal inclination with a quantitative measure like an angle is considerably more difficult as it requires accurate identification of clearly defined craniometric points. In the literature, the morphognostic terms “frontal bone inclination,” or “frontal profile,” are defined in numerous ways. The aim of this study was to determine which of these frontal inclination definitions is best suited for sex estimation. In a study in the context of the digital forensic osteology project, 10 of the frontal angle definitions described in the literature were assessed for their usefulness in sex determination on 211 virtual crania, reconstructed from postmortem CT-data. Custom-developed software was used for the automated measurement of frontal bone inclination angles from lateral-profile, volume-rendered 3D cranial images in which 10 anthropometric landmarks had been manually marked. Discriminant function analysis was performed to determine if satisfactory accuracy rates for the classification of sex could be achieved with defined variables. Four of the ten examined definitions were found to be highly significant for sex determination; three of these, also provided satisfactory intra- and inter-observer reliability. The frontal angle according to Schwalbe provided the best accuracy rate of 75.4% and a critical discriminatory value (separation value) of 88.6°: angles greater than this, suggest female sex; angles smaller than this, suggest male sex. Further, the open-source, custom-developed software introduced here proved compatible with commonly used image-processing and statistical programs and allowed quick, automated, valid measurement of numerous cranial angles. Other craniometric angles can, thus, also be quickly and easily determined with this software.
... Overall, our findings of various parameters were relatively higher than those found in the previously mentioned studies. Concerning with the imaging of FM, the present study detected that the studied Libyan population's parameters were larger compared to other ethnic groups [2,5,10,[18][19][20][21][22][23][24][25]. [14]. ...
Article
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Background: Foramen Magnum (FM) is the largest foramen of the skull and located in the most inferior portion of the cranium fossa as a part of the occipital bone. It's traversed by vital structures like medulla oblongata. There are dimensional differences between males and females which appeared larger in males.
... Overall, our findings of various parameters were relatively higher than those found in the previously mentioned studies. Concerning with the imaging of FM, the present study detected that the studied Libyan population's parameters were larger compared to other ethnic groups [2,5,10,[18][19][20][21][22][23][24][25]. [14]. ...
... Overall, our findings of various parameters were relatively higher than those found in the previously mentioned studies. Concerning with the imaging of FM, the present study detected that the studied Libyan population's parameters were larger compared to other ethnic groups [2,5,10,[18][19][20][21][22][23][24][25]. [14]. ...
Article
Full-text available
Background: Foramen Magnum (FM) is the largest foramen of the skull and located in the most inferior portion of the cranium fossa as a part of the occipital bone. It's traversed by vital structures like medulla oblongata. There are dimensional differences between males and females which appeared larger in males.
... In forensic and anthropological sciences, cranial analyses, whether morphognostic or morphometric, have played an important role in examining age at death, ancestry, biodistance, cranial variation and geographical relationships, cranial development, and, of course, sex differences (10). In addition, the information obtained from these analyzes can also be used in planning the surgical process to be performed in the cranial region. ...
... 47,48 Its morphological and metric analysis can also give an indication about the sex of the person in unidentified cases. [49][50][51][52] Although the FMI is described in the literature, 53 its classification or the categorization of crania based on this index is not detailed. The current study attempts to classify the crania on the basis of this index. ...
Article
Background: Human skull has been the most extensively studied bone for establishing the taxonomies at evolutionary levels. Crania are also the most commonly used skeletal elements in population studies because they are known to be more genetically driven and less affected by environmental factors. The craniofacial indices are considered as clinical anthropometric parameters used in the investigation of craniofacial skeletal deformities and brain development. The present research is an attempt to study the cranial indices in the South Indian population. Methods: The sample for the study included 118 dry adult crania. All the osteometric measurements were taken using standard anthropometric instruments, and 3 indices, namely, cranial index, orbital index (OI), and index of foreman magnum (FMI), were calculated. Cranial index is calculated as (maximum cranial breadth / maximum cranial length) × 100, OI as (orbital height / orbital breadth) × 100, and FMI as (transverse diameter / anteroposterior diameter) × 100. The crania were further classified based on these indices. Results: The cranial index ranged between 66.67 and 85.71 (mean, 78.57 [SD, 4.11]), the OI ranged between 68.89 and 102.63 (mean, 84.23 [SD, 6.64]), and the FMI ranged between 68.57 and 96.88 (mean, 79.71 [SD, 6.98]). Cranial index did not show any significant correlation with the OI (r = -0.162, P = 0.081) or the FMI (r = -0.045, P = 0.626). A statistically significant correlation was, however, observed between OI and FMI (r = -0.232, P = 0.012). Conclusions: The current study developed population-specific classification of crania using cranial indices. This craniometric baseline data pertaining to the craniofacial indices may be useful in presurgical planning and the postsurgical evaluation. It may also assist the forensic anthropologists in the categorization of human skulls, which may be an important component in identification of highly decomposed dead bodies and skeletal remains. More such studies need to be conducted to understand the effect of environment and genetics on the cranial shapes in different population groups.
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Objective: To compare whether there are any differences between the 3 methods used for measure area of foramen magnum (FM) in skulls. Methods: The FMs of 150 skulls were examined. Antero-posterior diameter, transverse diameter were measured using by Vernier caliper. The area of the FM was calculated by using 2 different formulas as described previously by Radinsky and Teixeira.The authors also applied stereological assessment method for estimating the surface area of FMs. The area was calculated 3 times manually using stereological point grid system for each skull.The authors compared the mean surface area of FMs obtained from each of these 3 methods estimating surface area of FMs whether there were any significant differences in between their results. Results: The mean areas of the FMs estimated according to Teixeria formula, Radinsky formula, and Cavalieri stereological method were respectively as follows: 790.47 ± 99.86 mm, 783.66 ± 99.34 mm, and 748.06 ± 100.19 mm. The authors observed significant differences (P < 0.05) in between the mean surface areas of FMs obtained from each of these 3 methods used for estimating the area. Conclusion: There were significant differences (P < 0.05) in between the mean surface areas of FMs obtained from each of these 3 methods used for estimating the area.
Article
Objective To evaluate whether sexual dimorphism of the morphometric measurements of foramen magnum (FM) and occipital condyles (OC) may be recognized using cone beam computed tomography (CBCT) images in a Brazilian population. Methods 309 CBCT scans (162 females; 147 males) were retrospectively selected and morphometric measurements were performed in both FM and OC (length, width, FM index and two calculated areas), totaling 10 parameters. All data were submitted to correlation (Pearson's correlation coefficient), descriptive (independent Student t test) and discriminant functional analysis to validate the expression of sexual dimorphism in the metric parameters of FM and OC (p<0.05). Results Excepted for the FM index, the measurements were higher in males (p<0.001). The strongest correlation was found between FM areas for both sexes (r=0.999). The OC maximum length was the best individual discriminator (81.2%). When FM and OC parameters were combined, the overall accuracy rate of sex estimation was 84.8%. Discussion and conclusion The morphometric measurements of FM and OC in CBCT exams are useful for sex estimation in adult Brazilians. OC parameters were more reliable individual discriminants, and when multiple parameters were combined, the highest accuracy was achieved.
Article
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The aging process has an impact on mandibular bone morphology and can therefore affect shape sexual dimorphism. Understanding the effect of senescence on mandibular shape changes is particularly important to correctly estimate the sex of an individual and predict age-related conformational modifications. The purpose of this study was to assess age-related changes in mandibular shape and sexual dimorphism. The study sample comprised 160 Multi Slice Computed Tomography examinations of individuals aged 40 to 79 years. Geometric morphometric analysis of fourteen osteometric landmarks was used to examine sexual dimorphism and patterns of mandibular shape variation with age. Results showed that mandibular sexual dimorphism of shape remained significant with aging. Conformational changes occurred between 50 and 70 years and were different for male and female individuals. Females presented earlier and more marked age-related shape changes than males. These observations suggest that mandibular senescence is a sexually dimorphic process since its onset, rate, and the areas subjected to conformational changes differ from male to female individuals. Senescence-related changes present substantial variability, and further investigation is required to determine precisely the age that marks their onset.
Article
Comparison of bony pieces requires that they are oriented systematically to ensure that homologous regions are compared. Few orientation methods are highly accurate; this is particularly true for methods applied to three-dimensional models obtained by surface scanning, a technique whose special features make it a powerful tool in forensic contexts. The aim of this study was to develop and evaluate a systematic, assisted orientation method for aligning three-dimensional cranial models relative to the Frankfurt Plane, which would be produce accurate orientations independent of operator and anthropological expertise. The study sample comprised four crania of known age and sex. All the crania were scanned and reconstructed using an Eva Artec™ portable 3D surface scanner and subsequently, the position of certain characteristic landmarks were determined by three different operators using the Rhinoceros 3D surface modelling software. Intra-observer analysis showed a tendency for orientation to be more accurate when using the assisted method than when using conventional manual orientation. Inter-observer analysis showed that experienced evaluators achieve results at least as accurate if not more accurate using the assisted method than those obtained using manual orientation; while inexperienced evaluators achieved more accurate orientation using the assisted method. The method tested is a an innovative system capable of providing very precise, systematic and automatised spatial orientations of virtual cranial models relative to standardised anatomical planes independent of the operator and operator experience.
Article
The skull presents a variety of morphological traits suitable for sex discrimination due to the degree of their development. The vertical frontal inclination has been established as another marker of sex discrimination, as a steep forehead is considered as a female and a receding frontal inclination as a male attribute. In the literature, there are many different ways to define the morphognostic term "frontal inclination" and "forehead profile" respectively. As part of the project "Digital Forensic Osteology" definitions of the frontal inclination commonly found in the literature have been tested with regard to their applicability to virtual skulls based on post-mortem CT data. The actual angle measurements were carried out automatically using software developed by the authors of this article. For the investigations, profile images of skulls generated from volume-rendered CT data were used in which anthropometric measuring points had been set manually. With the help of discriminant analysis it was tested whether sex discrimination on virtual skulls based on defined variables can be carried out with sufficient sensitivity. The measurement accuracy of the defined variables on the volume-rendered images turned out to be good. No significant sex differences regarding the tested variables were found. Using all the four selected variables the sensitivity for female skulls was only about 66 %, whereas for male skulls it was not much higher than the rate of coincidence (53 %). The results of this pilot study suggest that apart from extending the sample size the inclusion of additional variables based on strict consideration of validity and reliability criteria should be critically tested.
Article
Background: Individual distinguishing evidence may be an imperative field of measurable investigation which demonstrates higher correct expectation rates. This process of recognizable Evidence is facilitated by the assurance of sex and age. In circumstances where there are fragmented and mangled skeletal remains, sex assurance is moderately troublesome, and it becomes important to set up the precision of cadaver bones. Therefore, this study aims to evaluate sexual dimorphism and age determination by measuring foramen magnum (FM) dimensions in the Iranian population using digital computed tomography scan. Methods: The study sample consisted of a modern adult Iranian population of 120 males and 109 females (age range: 15-50 years). Length, width, and area of FM, also FM index were measured on base skull computed tomography scan. Result: All of the parameters of FM (length, width, area, and FM index), were larger in men than women. The accuracy of sex determination was up to 50.2. The highest accuracy for sex determination was FM width (67.9). This study also helps craniofacial surgeon for exact reference value of FM, which are authorize neurosurgeons' accessibility to the brain stem approach and FM region with minimum retraction. Conclusions: It can be concluded from the result, that morphometric analyze of FM is useful for sex determination but cannot be suitable for age determination.
Article
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In this study the foramen magnum was analyzed for sex differences using standard osteometric techniques. We analyzed 100 (55 males and 45 females) skulls from the department of Anatomy, Yenepoya Medical College which were in good condition with a record of sex. The cranial base was visually assessed for foramen magnum shape. Morphometry (anteroposterior diameter (APD)& Transverse diameter (TD)) was determined and their differences by gender (p <0.05) were ascertained. Oval shape was the most common followed by round, tetragonal and pentagonal in both sex. The results demonstrated that sexual dimorphism is present in the foramen magnum. APD and TD were higher in male skulls than females (34.04 vs 31.72 and 28.63 vs 26.59). In incomplete skeletons, metric analysis of the foramen magnum may provide a statistically useful indication as to sex of the unknown skull.
Article
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The purpose of this study was to evaluate the radiological measurements of the foramen magnum (FM) and their relation to sex as well as to note variations in the shape of the FM. Cranial computerized tomographic images (CT) of 110 normal subjects (57 males - 53 females) between the ages of 18 and 80 years were examined in this study. The sagittal and transverse diameters of the FM were measured with a millimetric sliding caliper. Additionally, the area of the FM was also estimated. The statistical analysis for sex comparison was made using Student's t test. To determine the relationships between the studied parameters, Pearson correlation coefficients were calculated. In addition, the frequency percentage ratios of the variable shape types of the FM were also determined. Our findings showed that the sagittal, transverse diameters and area of the FM were significantly greater in males than in females (P < 0.001). The statistical comparisons of the correlations between all measuring parameters showed significant associations (P < 0.01). According to the identity with the shape type, the FM was found to be oval in 8.1%, egg-shaped in 6.3%, round in 21.8%, tetragonal in 12.7%, pentagonal in 13.6%, hexagonal in 17.2%, irregular (A) in 10.9% and irregular (B) in 9.09%. It can be concluded that the sex differences in the dimensions of the FM and the variations in its shape are of diagnostic clinical and radiological importance.
Article
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Las medidas antropométricas están siendo ampliamente utilizadas para el acompañamiento y el desenvolvimiento de niños, en la verificación de las adaptaciones en respuesta a entrenamiento, en la seleción de atletas y en estudios de caracterización étnica, entre várias otras áreas. El control da la calidad de esas medidas va a resultar en datos mas confiables y medidas antropométricas mas precisas. El propósito del presente estudio es el de difundir la estrategia para la obtención del error técnico de medición (ETM), siguiendo la metodología de Kevin Norton y Tim Olds (2000) y evaluar el desempeño de empleados de laboratorio. Tres antropometristas del Laboratorio de Fisiologia del Ejercicio (Labofise) de la Universidad del Brasil fueron evaluados. Ellos realizaron las medidas de pliegues cutáneos (Cescorf, 0.1mm) en nueve diferentes puntos antropométricos de 35 voluntarios (25,45 ± 9,96 años). Para las medidas, fue adoptada la padronización de la International Society for Advancement in Kinanthropometry (ISAK). Para la verificación del ETM intra-evaluador, las medidas fueron realizadas en los mismos voluntarios en dos días diferentes; y, para la obtención del ETM inter-avaliador, las medidas fueron hechas en un mismo grupo de voluntarios, en el mesmo dia, por los tres antropometristas. Los resultados apuntaron ETMs no aceptables apenas para dos evaluadores en el análisis intra-evaluador. Los demás ETMs alcanzaron resultados aceptables. Los ETMs no aceptables demostraron la necesidad de entrenamiento técnico de los antropometristas, de modo de minimizar la variabilidad constatada.
Article
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The purpose of this study is to assess the presence of sexual dimorphism in the foramen magnum size. We analyzed 211 human skulls from the collection of the Universidade Federal de São Paulo, with a record of sex and age determined using anteroposterior and transverse diameters of foramen magnum, and their differences by gender (p<0.05) were ascertained. Fischer linear discriminant function was calculated and the value for the classification of these variables was determined. All the dimensions were found to be higher, and in men's skulls, the foramen magnum size had low discriminating power and were accurately classified only in 66.5% skulls. Our results show that this quantitative indicator is of limited practical value and should be supplemented with qualitative indicators of sexual dimorphism in the occipital bone to improve the accuracy in the sex diagnosis.
Article
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The anthropometrical measurements have been widely utilized to follow children's development, in the verification of the adaptations to the physical training in the athletes' selection, in studies of ethnic characterization, among others. The control of the precision and accuracy of the measurements will result in more reliable data. The objective of the present study was to diffuse the strategies to compute the technical error of measurement (TEM) according to Kevin Norton's and Tim Olds methodology (2000) and to analyze the laboratory' trainees performance. Three beginner observers (anthropometrists) of the Exercise Physiology Laboratory (Labofise) of the University of Brazil were analyzed. They accomplished measures of skin folds thickness (Cescorf, 0.1 mm) in nine different anthropometric points in 35 volunteers (25.45 ± 9.96 years). To accomplish the measures the International Society for Advancement in Kinanthropometry (ISAK) was adopted. For the TEM intra-evaluator verification, the measures were accomplished in the same volunteers in two different days and, to obtain the inter-observers TEM, the measures were accomplished in a same group of volunteers, in the same day by the three evaluators. The results indicated not acceptable TEMs only for two evaluators in the intra-evaluator analysis. The other TEMs reached acceptable results. Not acceptable TEMs demonstrated the need of technical training of evaluators in order to minimize the variability verified.
Article
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The determination of sex from human skeletal remains is of fundamental importance in both medicolegal and bioarchaeological investigations. In the present study, the basal region of the occipital bone in a documented French collection was analyzed for sex differences using standard osteometric techniques. The results demonstrated that a low level of sexual dimorphism is present in the cranial base of this sample, with few of the measured variables exhibiting statistically significant differences between the sexes. The cross-validated classification accuracies obtained in this study for the derived discriminant functions are appreciably lower than those previously reported for other disparate populations. A stepwise procedure, which selected maximum length of the left occipital condyle and minimum distance between occipital condyles (MnD), produced the best overall result with a classification accuracy rate of only 67. 7%. The most effective single dimension, bicondylar breadth (BCB), also correctly classified 67. 6% of the individuals examined, but with a much higher sex bias. Osteometric analysis of cranial base dimensions, therefore, cannot be regarded as a sufficiently reliable method for determining sex in this population group. © 2010 Société d'anthropologie de Paris et Springer-Verlag France.
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This is the author's PDF version of an book chapter published in Current and Recent Research in Osteoarchaeology 2 ©1999. The paper was originally delivered at the sixth meeting of the Osteoarchaeological Research Group at the Institute of Archaeology, University of Durham on 7 June 1997. It is important for workers to have some estimate of the degree of error evident when measuring objects. Although many use their own "rule-of-thumb" to give them the personal satisfaction that they are working accurately, measures of error, or conversely reliability, are rarely given in the lierature. Some simple, useful equations are given that may be used privately or when reporting metrical work.
Article
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Annual Review of Anthropology http://arjournals.annualreviews.org/loi/anthro
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The metric values of the foramen magnum (FM) were studied both by dry skull measurements and tomographic measurements. Anteroposterior (AP) and transverse diameters of 88 skulls in three different groups were taken into consideration. The mean AP value for the 38 skulls of the first group (Late Byzantine Era, A.D. 13th century) was 35.6 +/- 2.3 mm, while the mean transverse value was 29.9 +/- 2.1 mm. Twenty-seven skulls of the 20th century had the mean values of 35.1 +/- 2.8 and 28.7 +/- 2.2 mm for AP and transverse measurements, respectively. The third group consisted of computed tomography (CT) measurements of 23 outpatients in the radiology department. Their mean AP value was 36.4 +/- 2.8 and the mean transverse value was 30.0 +/- 1.4 mm. When the measurements of 88 skulls of the three groups were considered together, the mean AP value was 35.6 +/- 2.7 and the transverse value was 29.5 +/- 2.1 mm. There is no significant difference between the total mean value of the present study and that of other authors. However, if the three groups are considered separately, the mean transverse value shows significant differences, especially that of the second group. Also the radiographic and tomographic measurements of other authors have higher results than the present results, perhaps due to methodologic differences.
Article
If DNA cannot be isolated, don't give up the identification! The author has used for the same purpose methods ranging from physical anthropology to forensic medicine and especially a recent method of comparison of epigenetic traits, which proved to be very useful for the identification of family related skulls in connection with historical and other data. The kinship of 18 identified skulls (buried together in a family vault) is established by comparison of X-ray images of paranasal cavities (frontal and maxillary sinuses, orbital and nasal cavities), the shape and size of which are strongly genetically determined. The comparison also extends to numerous other epigenetic trait similarities on the skulls. It is recommended for: scientists working on human identification and studying heredity, forensic scientists, physical anthropologists, radiologists, stomatologists, paleopathologists, geneticists, historians and many others.
Article
Erstmalig für den deutschen Sprachraum wird ein methodisches Kompendium vorgelegt, mit dessen Hilfe eine umfassende Bearbeitung von historischen menschlichen Skelettresten ohne weiterführende Literatur möglich ist. Dargestellt ist das gesamte gängige methodische Repertoir von der Ausgrabung bis zur vergleichenden Auswertung der Daten. Ein Schwergewicht liegt auf moderner Laboranalytik (u.a. Spurenelement- und DNA-Analyse). Ziel und Nutzen des Buchs sind, daß ein Bearbeiter/Ratsuchender/Studierender allein mit dem vorliegenden Werk seine Arbeit planen und durchführen kann. Hierzu dienen besonders ausführliche Rezepturen und Fallbeispiele, Illustrationen und anatomische Abbildungen. Auf ungewöhnliche Überlieferungsformen menschlicher Überreste (Leichenbrände, Mumien, Moorleichen) wird ebenfalls und ausführlich eingegangen.
Chapter
This chapter focuses on the relationship between race and age-related bone loss. The wide ranges in bone mass and in the incidence of osteoporotic fracture observed across ethnic groups and geographic regions confirm that many factors affect the determination of osteoporosis risk. Interethnic studies that include a wide variety may help elucidate possible etiologies in the pathogenesis of osteoporosis. In order to best delineate these factors, investigators must explore contributions from the genetic, environmental, and cultural milieu that characterize different groups of people. Bone mass, in and of itself, may not best predict fracture risk in all groups. Variables such as rates of bone turnover, bone geometry, calcium intake and metabolism, vitamin D status, body composition, and life-style factors contribute to fracture risk, reflecting the rich diversity and flexibility in adaptation that is peculiar to the human species.
Article
Introdution: The morphological characteristics obtained by craniometry may be the key to sex determination and enable us to identify unknown individuals in anywhere in the world. Aims: The purpose of this study was to evaluate the effectiveness of the linear morphometry of foramen magnum to verify the morphological characteristics for gender determination in human skulls of Brazilian individuals. Methods: With a digital caliper, were made three non-consecutive measurements of the foramen magnum in 215 human skulls (139 male and 76 female), from the collection of the Department of Morphology and Descriptive Topography - UNIFESP/SP with registered data on nationality, gender, and age. The craniometric measurements were made in accordance with the protocol defined by Günay and Altinkök (2000). The data were submitted to intraclass correlation coefficient (ICC) and Student t-test with significance level of 5%. Results: There were no statistically significant differences (chi-square, p > 0.05) between the ethnic groups within each gender. The ANOVA and Tukey tests showed that the gender influenced the width of the foramen magnum. The FM is higher in males (30.3 ± 0.20) than in females (29.4 ± 0.23), but not in length (p < 0.05). Conclusion: The morphometric linear method of the foramen magnum (width) was able to determine the morphological differences between sexes and can be used in conjunction with other anthropological techniques to gender determination of unknown individuals.
Article
Understanding the complexities of cranial base development, function, and architecture is important for testing hypotheses about many aspects of craniofacial variation and evolution. We summarize key aspects of cranial base growth and development in primates that are useful for formulating and testing hypotheses about the roles of the chondrocranium and basicranium in cranial growth, integration, and function in primate and human evolution. We review interspecific, experimental, and ontogenetic evidence for interactions between the cranial base and brain, and between the cranial base and the face. These interactions indicate that the cranial base plays a key role in craniofacial growth, helping to integrate, spatially and functionally, different patterns of growth in various adjoining regions of the skull such as components of the brain, the eyes, the nasal cavity, the oral cavity, and the pharynx. Brain size relative to cranial base length appears to be the dominant influence on many aspects of basicranial variation, especially the angle of the cranial base in the midsagittal plane, but other factors such as facial size, facial orientation, and posture may also be important. Major changes in cranial base shape appear to have played crucial roles in the evolution of early primates, the origin of anthropoids, and the origin of Homo sapiens.
Chapter
This chapter focuses on environmental(or nutritional) contributions to age-related bone loss and the maintenance of bone tissue by the elderly, with emphasis on the micronutrients that are needed to maintain bone mineral content (BMC) and bone mineral density (BMD) late in life. A balanced selection of foods is recommended for each day, but a large percentage of the elderly population fail to achieve this balance, especially in the consumption of bone-related nutrients from plant sources such as cereals, vegetables, fruits, as well as from dairy products. This failure is an age-old problem, but the solution for it is not simply the recommendation of taking a multinutrient supplement. Excessive reliance on supplements does not typically provide the non-nutrient phytochemical molecules that are rich in plant sources. Many other plant molecules may also have health-promoting effects on human skeletal tissue, but prospective studies of elderly human subjects are currently in progress. A balance of nutrient intake also implies getting the appropriate proportions of calcium and phosphate, and of sodium and potassium, so that imbalances do not contribute to calcium and bone losses. Other nutrients in excess, notably the acid-forming proteins from animal foods, may also contribute to losses of calcium and bone mineral. Typically, the nutrients consumed in excess, phosphate, sodium, and even animal protein, exert their adverse effects on calcium and bone metabolism through elevations in parathyroid hormone (PTH).
Chapter
Individual variations in circulating levels of sex steroids with aging may have important effects on the bone, as aging is associated with decline in the sex steroids. This chapter reviews the role of changes in levels of estrogen (menopause), testosterone (andropause), and the adrenal androgen, dehydroepiandrosterone (DHEA) and its sulfated derivative DHEA(S) (adrenopause) on skeletal aging. With the onset of menopause, estrogen deficiency is associated with a rapid bone loss, which estrogen therapy prevents by inhibiting bone resorption. Recent data indicate that low estradiol levels and high levels of sex hormone-binding globulin (SHBG) in older women are associated with reduced bone density and increased fracture risk. Estrogen is important for bone maturation and accretion in men, and bioavailable estradiol levels are significantly correlated with bone density in older men. Some reports indicate that in men, there is an increase in SHBG and a decrease in total and free, or bioavailable, testosterone with aging. Levels of free testosterone have been associated with bone density in men. Low DHEA adrenal androgen levels are of potential risk for the skeleton for two reasons: androgens provide an anabolic effect on bone mass, and these androgens, DHEA(S) and androstenedione, are precursors of estrogens by aromatization in peripheral tissues.
Chapter
Time is a wicked thing. It has no tangible substance, and yet it has an extremely solid autonomy, advancing ever so constantly. And, most wickedly, its correlation to other things is often lamentably weak. This weak interdependence between time and many other natural phenomena is the cardinal reason for the difficulties which exist in human biology in assessing the two variables historic dating of human remains and age at death. In particular the problem of age estimation has been approached by many methods developed in the last decades — which illustrates that the existing techniques were always insufficient.
Article
This article has no abstract.
Article
This paper summarizes work in discriminant analysis. Normal theory and discrete results are discussed. Estimation of error rates and variable selection problems are indicated. Current research problems are considered: robustness, nonparametric rules, contamination, density estimation, mixtures of variables.
Article
The current paper explores the impact of age and sex on adult cranial shape and size variation in the documented collections from St Bride's and Spitalfields. The scope is to assess the extent to which it is valid to pool age and sex groups in inter-population comparisons that use cranial data. For this purpose, age and sex differences in cranial shape and size were explored using multivariate analysis of variance, Discriminant analysis and Mann–Whitney tests. The results suggest a clear change in cranial shape with increasing age; however, this change is not statistically significant. Therefore, it is justifiable to pool different age groups in bioarchaeological analyses. Increasing age also has a minimal impact on cranial size among females, whereas among males, its impact is small but statistically significant. Finally, cranial shape and size are significantly different between males and females, irrespective of their age. This dimorphism can be used for the assessment of sex, although attention should be given to over-classification problems when using discriminant analysis. Copyright © 2012 John Wiley & Sons, Ltd.
Article
We present a new approach called computational shape analysis, which utilizes a Fourier-wavelet representation for characterizing shape features of 2-D forms commonly encountered in a wide set of sub-disciplines within the biological sciences. The morphology of interest consists of the human cranial base (CB) as depicted on lateral cephalometric radiographs. Given a complex irregularly bounded form in Cartesian coordinate space, we first compute elliptical Fourier functions (EFFs) using a set of closely-spaced pseudo-homologous (x, y) points, starting at basion, to create a precise analog of the closed contour. This computed contour is then scaled (size-standardization) and rotated (positional-orientation) to provide for a common normalization. This insures that the representation is invariant with respect to starting point, size and orientation. Utilizing the EFFs, global aspects of the CB can then be extracted. The coordinates derived from the EFF were subsequently submitted to a continuous wavelet transform (CWT). Wavelet coefficients were then computed to identify localized features. The significant advantage of wavelets is that they are able to objectively identify changes in boundary curvature, thereby depicting localized aspects not easily attainable with other methods. Utilizing a sample of 297 Japanese cranial base outlines, statistically-significant differences in sex and archeological age were found. Although archeological age differences were present, they were small and largely random in character, suggesting stability in the CB structures. The presence of sexually dimorphic differences is consistent with earlier data derived from studies of Macaca nemestrina. In the current study, these differences in sexual dimorphism were present for every group starting with the Yayoi period and continuing up to the Modem period. Consequently, one may infer that the pattern of sexual dimorphism documented in the Japanese CB, is a primate pattern with an ancient evolutionary history. Wavelets were particularly useful in objectively identifying this sexual dimorphism. The results demonstrate that the Fourier-wavelet representation is a practical approach for numerically describing and visually depicting both global and localized features.
Conference Paper
The adult human occipital bone offers opportunities to develop measurements that can aid in the identification of human remains, particularly as it tends to survive inhumation and physical insults more readily than many other bones of the skull. The occiput has a number of anatomical features, some of which have been evaluated for sex and ancestry differences including the occipital condyles and the foramen magnum. Using these features, ten measurements of the occipital region were chosen from past publications. In addition, the position of the hypoglossal canals offered an opportunity to develop two new measurements. Twenty skulls of unknown sex and ethnicity were obtained, their occipital regions examined, and a number of measurements performed. Twelve measurements were recorded to two decimal places using digital (Mitutoyo) sliding calipers. Parts A, B and C of this experiment examined intraobserver error, multiobserver error and variation between twenty skulls by using the coefficient of variation. This study aimed to define and evaluate measurements that may be used in identification of human cranial remains, and forms part of a wider study on sexual differences of the condylar region of the human occipital bone. These initial results indicate that while all measurements have the potential to prove useful, the bicondylar breadth, the distance between the external hypoglossal canals, the length of the foramen magnum and the width of the foramen magnum are the most clearly defined, and may offer greater potential in sex identification.
Article
Age-dependent cortical bone loss was investigated in an earlier British population. The study sample comprised female skeletons from the 18th/19th century crypt at Christ Church, Spitalfields, London. Bone loss was monitored using metacarpal radiogrammetry. Age at death was known exactly from coffin plates. Results indicated that peak cortical thickness was less than in modern subjects. Continuing periosteal apposition was evident throughout adulthood, and the rate of increase in metacarpal diameter resembled that in modern subjects. Bone loss from the endosteal surface was evident from the fifth decade onwards, and this outstripped the rate of subperiosteal gain so that there was a net loss of cortical bone with age. Cortical bone loss occurred at a similar rate to that in modern subjects. In contrast to modern populations, there was no evidence that loss of cortical bone was associated with increased propensity to fracture. The present results, together with those previously published for a British medieval skeletal assemblage, suggest that patterns of cortical bone loss in women have remained unchanged over at least the last millennium in Britain. Given the great changes in lifestyle which have occurred during this period, this suggests that lifestyle factors may be rather less important than is sometimes asserted in influencing the severity of osteoporosis, at least as far as loss of cortical bone is concerned. Am J Phys Anthropol 112:349–361, 2000. © 2000 Wiley-Liss, Inc.
Article
Intended for anyone who to learn or brush up on the basic of statistics but is anxious about their abilities, this book offers a slow-paced, entertaining introduction to the topic. Using playful headings to encourage students to read further, the book begins with an introduction to the "language" of statistics, and then covers descriptive statistic (from computing measures of central tendency to distributions and curve plotting to graphing data) and inferential statistics (including probability, statistical significance, correlation/regresion, ANOVA, and multiple regresion). Througnout this book, Salkind offers: a difficulty rating index for each chapter's material, tips for doing and thinking about statistical technique, top ten for everything from the best ways to create a graph to the most effective techniques for adata collection, tech talk boxes for readers who want additional details and commentary on statisticsal procedures, things to remember that offer readers reviews and reminders of how material presented earlier relates to a technique being presented, steps that break statistical techniques down into a clear sequence of procedures, SPSS tips for executing each major statistical technique and time to practice exercises at the end of each chapter, followed by complete worked-out solutions. The book concludes with a statistical software sampler and a description of the best Internet sites for statistical information and data resources
Article
The foramen magnum is an important landmark of the skull base and is of particular interest for anthropology, anatomy, forensic medicine, and other medical fields. Despite its importance, few osteometric studies of the foramen magnum have been published so far. A total of 110 transverse and 111 sagittal diameters from Central European male and female dry specimens dating from the Pleistocene to modern times were measured, and related to sex, age, stature, ethnicity, and a possible secular trend. Only a moderate positive correlation between the transverse and the sagittal diameter of the foramen magnum was found. Surprisingly, neither sexual dimorphism, individual age-dependency, nor a secular trend was found for either diameter. Furthermore, the relationship between the individual stature and foramen magnum diameters was weak: thus foramen magnum size cannot be used as reliable indicator for stature estimation. Further consideration of possible factors influencing the variability of human foramen magnum size shall be explored in larger and geographically more diverse samples, thus serving forensic, clinical, anatomical, and anthropological interests in this body part.
Article
Fragmentary human remains compromised by different types of inhumation, or physical insults such as explosions, fires, and mutilations may frustrate the use of traditional morphognostic sex determination methods. The basicranium is protected by a large soft tissue mass comprising muscle, tendon, and ligaments. As such, the occipital region may prove useful for sex identification in cases of significantly fragmented remains. The aims of this paper are to (1) evaluate sexual dimorphism in British cranial bases by manually recorded unilateral and bilateral condylar length and width as well as intercondylar measurements and (2) develop discriminant functions for sex determination for this cranial sample. The crania selected for this study are part of the 18th-19th century documented skeletal collection of St. Bride's Church, Fleet Street, London. Adult human skulls (n = 146; male75/female71) were measured to derive statistical functions. Results indicated that expression of sexual dimorphism in the occipital condylar region within the St. Bride's population is demonstrable but low. Crossvalidated classification accuracy ranged between 69.2 and 76.7%, and sex bias ranged from 0.3 to 9.7%. Therefore, the use of discriminant functions derived from occipital condyles, especially in British skeletal populations, should only be considered in cases of fragmented cranial bases when no other morphognostic or morphometric method can be utilized for sex determination.
Article
Knowledge of the degree to which various subsets of morphological data reflect molecular relationships is crucial for studies attempting to estimate genetic relationships from patterns of morphological variation. This study assessed the phylogenetic utility of six different human cranial regions, plus the entire cranium. Three-dimensional landmark data were collected for 83 landmarks from samples of skulls from 14 modern human populations. The data were subsequently divided into anatomical regions: basicranium, upper face, mandible, temporal bone, upper jaw, cranial vault, and a subset of points from around the entire cranium. Depictions of population molecular distances were calculated using published data on microsatellites for the same or closely related populations. Distances based on morphological variation of each of the anatomical regions were compared with molecular distances, and the correlations assessed. The morphology of the basicranium, temporal bone, upper face, and entire cranium demonstrated the highest correlations with molecular distances. The morphology of the mandible, upper jaw, and cranial vault, as measured here, were not significantly correlated with molecular distances. As the three-dimensional morphology of the temporal bone, upper face, basicranium, and entire cranium appear to consistently reflect genetic relationships in humans, especially with more reliability than the cranial vault, it would be preferable to focus on these regions when attempting to determine the genetic relationships of human specimens with no molecular data.
Article
In this paper some of the common misuses of discriminant analysis are discussed. The problems fall into four groups: 1. Study goals are unfocused; 2. improper sampling procedure; 3. assumptions are violated; 4. variables are poorly defined or selected. Identification of these problems leads to the appropriate corrective action.
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Metric and statistical methods were used on a series of skulls (n = 100) to examine the relationship of size and shape parameters of the occipital condyles with other skull variables, which might contribute to an understanding of the morphological variability of occipital condyles and the functional importance of the cranio-vertebral joint (occipital-atlantal-joint) in man. A total of 67 metric variables were included which could be classified into three groups: a) linear measurements, indices and angles of the size and position of the condyles (length, breadth, height and size of the condyles surfaces; length-breadth, length-height and breadth-height indices of the condyles; distance measurements and inclination angles of condyles in the horizontal frontal planes). The size of the condylar surfaces was determined using the printing method of Stofft and Müller. b) Length and breadth measurements and angles of the occipital bone on which the condyles are situated; c) Size circumference, weight and volume measurements of the cranium. The variables of groups b) and c) were mostly taken according to the metrical scheme of Martin. Statistical analysis of the material includes measures of frequency distributions (means, variances, skewness and kurtorsis) and intercorrelations of the variables. Most of the metrical characters of the condyles show high intercorrelations. Similarily, to a large extent highly significant correlations were found between variables of the condyles and length and breadth measurements of pars basilaris and lateralis of the occiput, while little or no statistical association was observed with the size variables of squama occipitalis. The same is true of the correlations between metrical characteristics of the condyles and most of the measurements of the cranium. Likewise cranial capacity and weight of the cranium show little correlation with condylar measurements. Therefore the present study does not support the existence of a relationship between cranial weight or the pressure on the cranio-vertebral joint, and the size and position of occipital condyles as supposed by zoologists on the basis of research work on different species of mammals. However the size and distance measures of the condyles show significant correlations with skull height (basi-bregmatic height) and the length of the skull base (basi-nasal length). The highest correlation coefficient values (r = 0.5) were observed between skull height and the size of the surface of the condyles and the length of the condyles. Somewhat smaller but statistically significant r values were found between basi-bregmatic height of skull and the distance measurement between the condyles. The correlation coefficients demonstrate that skull of greater height possess the condyles which are not only larger and longer but show increased distance between the condyles as well, resulting in a larger supporting area for the skull...
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Anatomical measurements are made on the clivus and the upper cervical column. These values are important for transoral, transpalatinal approaches to the clivus and to atlas and axis. The mean-values of the length of clivus in adults were 45 mm on the internal cranial base, on the external the length between the basion and the vomer was estimated with 27.9 mm, the tuberculum pharyngeum is situated on our material 11.2 mm rostral of the basion. The anterior part of clivus in the external cranial base has a width of 22.5 mm, the posterior part has one of 42.8 mm. Included are measurements of the hypoglossal canal and measurements of foramen lacerum externum. The postnasal enlargement of the most portals of the cranial base is given in Fig. 5. The occipital condyles are 22.9 mm in length, the angle between the condyles was 51.4 degrees. The thickness of clivus was 18.3 mm in a level 28 mm rostral of basion and 9.3, 11 mm rostral of basion. Given are also the thickness of substantia corticalis of clivus and the area of posterior wall of sphenoid sinus. Measured are also the distances between dens axis and anterior arch of atlas and basion. The height of anterior arch was found larger than by other researchers. Included are length and width values of the upper cervical column and the insertion areas of the longus capitis and rectus capitis anterior muscles.
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We analyze the taxonomic structure of European populations at three time periods, the Early Middle Ages, the Late Middle Ages and the Recent Period. The data consist of sample means for 10 cranial variables based on 137, 108, and 183 samples for the three periods. Clustering by standard numerical taxonomic procedures reveals that the data are represented only poorly as hierarchic classifications. The clusters form significant and moderately strong associations with an arrangement of the samples by regions (geography) and by language family. Whereas during the early period, language family showed a stronger association with clusters based on cranial morphology, in the recent populations these clusters correspond better with geography than with language. Ordinations of these populations by means of nonmetric multidimensional scaling shows the continuity of the taxonomic structure at all three periods. Only a few populations are outliers. The relations between phenetic distances (cranial morphology), geography, and language are examined by means of multiple Mantel tests. At all three periods geography is correlated somewhat more strongly with phenetics than is language affiliation, but the correlation with the latter increases with time. When the data are pooled over the three periods, the populations tend to group by language affiliation more than they do by period. Ordination of the pooled data reveals language patterns rather than patterns due to period, showing strong shifts in cranial measurements through time. These analyses show that while there is no clear-cut taxonomic structure in European populations that would justify the traditional classifications based on the crania, there are significant and important associations with both language affiliation, geography, and time period, in this order. These patterns are likely to have become established through the migration and subsequent expansion of populations into their areas of occupation during the time interval studied rather than by geographic differentiation in situ.
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This study of 500 male and female skulls proves: significant differences of correlation coefficients (p less than or equal to 0.01) occur between the two sexes. The combined variables are: 1. bizygomatic breadth (45)/skull base length (5) 2. bizygomatic breadth (45)/foramen magnum length (7) 3. bizygomatic breadth (45)/foramen magnum breadth (16) 4. bizygomatic breadth (45)/basion-bregma height (17) 5. foramen magnum breadth (16)/skull base length (5) Female skulls have generally higher correlation coefficients values than males which is interpreted as an indication of homogeneous growth.
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The cranial base can be used to determine the sex of fragmentary or deformed skulls. An initial study used nine measurements taken from 100 crania in the Terry Collection. The sample was divided equally by race and sex. Six regression models were formulated that predicted correctly the sex of the sample with 71-90% accuracy. In a separate test, a control sample of 20 skulls, also drawn from the Terry Collection but not involved with formulating the regression equations, was correctly classified with 70-85% accuracy.
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At cranial level, external apposition during ageing has been postulated by some authors. In longitudinal studies, a gradual increase of cranial diameters has been shown by cephalometry (Kendrick et al. 1967) or by lateral radiography (Israel 1968, 1970). However, these results are contested at methodological level by other longitudinal studies (Tallgren 1974). It is the aim of this study to analyse, in a cross-sectional sample, the effects of senescence on several cephalic dimensions. A series of skulls of known age and sex has been selected for this purpose.
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The sex of unidentified skeletons is not always easily and correctly determined by the general medical examiner with no formal training in forensic anthropology. Sometimes the diagnostic procedure may be extremely complicated when handling fragmented bones. The present preliminary observations concern the evaluation of the size of the foramen magnum in 40 skulls (20 of each sex). Our results indicate that this method may be useful in the sexing of skeletal remains under the above-mentioned conditions as well as when an expert in forensic anthropology or a crime laboratory is not available.