The value of the size of foramen magnum in sex determination

Morphometric analysis of the skulls of a ram and ewe Romanov sheep (Ovis aries) with 3D modelling

BACKGROUND

With the development of technology, 2D images have left their place for 3D models. The 3D modelling technique is widely used in plastic surgery, orthopaedic surgery, neurosurgery, traumatology, dentistry and medical education. The skull is important in terms of containing the starting parts of systems with vital functions.

OBJECTIVE

The aim of the study is to reveal the difference between male and female and other species by 3D (three-dimensional) modelling and craniometric measurements of Romanov heads.

METHODS

In our study, skulls of Romanov sheep (10 females and 10 males) older than 1-year-old were used. The heads of Romanov sheep were scanned with computed tomography and modelled in 3D.

RESULTS AND CONCLUSIONS

In the study, it was determined that there was a statistically significant difference between male and female sheep in terms of the largest nose length, facial width, molar row length, viscerocranium length, and foramen magnum height parameters (p < 0.05). It was determined that the greatest width of the foramen magnum measurement parameter and the skull index showed statistically significant differences between the genders at the p < 0.01 level. No statistically significant difference was found in other measurements (p > 0.05). The data obtained as a result of the study will help in the racial discrimination and classification of bones obtained from zoo archaeological excavations.

Radiological examination of the skull of Siirt-coloured mohair goat, Romanov and Hamdani sheep

The skull is a vitally important complex structure formed by the combination of many bones. Craniometric studies are performed with various imaging methods to determine morphometric characteristics in animals. One of these methods is radiography. In our study, skulls of 14 Hamdani sheep, 20 Siirt-coloured mohair goats and 20 Romanov sheep breeds were used. Skull sections were taken with a computed tomography device and saved in DICOM format. Nine separate measurements and six index calculations were made from the images. In the study, firstly, the gender difference was ignored and the similarities and differences between the species were recorded. In addition, gender differences were determined statistically, without making any distinction between species. Correlation analysis was performed to compare measurement parameters between animal species. As a result of the study, the highest skull length (SL) and cranial length (CL) values were determined in the Siirt-coloured mohair goat. It was determined that the difference between Romanov sheep and Siirt-coloured mohair goat in CL parameter was not statistically significant (p > 0.05). In addition, a statistically significant difference was observed between the Romanov sheep breed and the Hamdani sheep breed (p < 0.01). The external length of the cranium (ELC) measurement parameter was found to have a statistically significant difference in three animals (p < 0.01). According to the results of the correlation analysis, the highest correlation value was determined between cranial width (CW) and CL parameters (r = 0.920). When the species difference was ignored, and the statistical difference of the internal height of the cranium (IHC) parameter was found to be significant between female and male animals (p < 0.05). In addition, it was determined that SL, CW and internal cranium index (ICI) parameters had a significant difference depending on sex (p < 0.01). It is foreseen that the obtained data can be used in sciences such as zoo archaeology, anatomy, surgery and forensic medicine.

Morphometric analysis of the foramen magnum in sex estimation: An additional 3DCT study from Nepal on a larger sample

Background

Estimation of sex of the skeletal remains plays a vital part in the identification of an individual. This study is focused on the morphometric measurements of the foramen magnum region and examining the accuracy of sexual dimorphism in the Nepalese population.

Methods

Measurements were obtained from 3D computed tomography (CT) scan of 261 Nepalese adult cranial bases with known age and sex. Length and breadth of the foramen magnum, length and breadth of right and left occipital condyles and maximum and minimum intercondylar distance were measured on the base of the skull CT images.

Results

The mean values for all parameters were higher in males than females except for the maximum intercondylar distance. Sex prediction done with discriminant function analysis could classify the skull with an overall accuracy of 70.5%-71%.

Conclusions

It can be concluded from the results that the morphometric study of the foramen magnum is less reliable for sex estimation in the Nepalese population.

Cone-Beam Computed Tomography: A New Tool on the Horizon for Forensic Dentistry

Teeth and bones of calvarium are important structures from a forensic point of view, as they are extremely resilient to destruction or decomposition, even under temperature variations. Radiology is inevitably an important tool in forensic investigations. Maxillofacial radiology provides a considerable amount of information for the identification of remains and evidence in case of legal matters. The advent of cone-beam computed tomography (CBCT) in the arena of maxillofacial 3D imaging has contributed immensely to forensic science such as the age estimation through teeth, analysis of bite marks, determination of race and sex, etc. The advantages of accuracy in imaging the anatomy, digitized technology favoring easier comparison of records and storage of records for a longer period, cost reduction, dose reduction, and easier portability have made it an unavoidable adjunct in forensic investigations. The aim of this paper is to review and highlight the importance of CBCT in successful forensic identification and analysis. This review is written to address the various aspects of CBCT as a recently developed technology that may be very useful in some forensic contexts, based on searches for current studies in the literature using PubMed, Scopus, Web of Science, and Google Scholar databases, to identify studies published since inception to December 2021, with no language restriction. In conclusion, CBCT is an accessible 3D imaging technology with many applications, one of them being in forensic sciences.

Morphology, morphometry and some aspects of clinical anatomy in the skull and mandible of Sharri sheep

The aim of this study was to investigate and record data on the morphometrical parameters of the skull and mandible in Sharri sheep. We have evaluated 34 skulls (24 females and 10 males) of Sharri sheep (Ovis aries), a local breed of sheep from Northern Macedonia. Fifty-one measurements were evaluated in total: 37 parameters on the skull and 14 parameters on the mandible. The results of the study show that, in general, the morphology and morphometric parameters of the skull and mandible, of Sharri sheep are similar to those of other sheep breeds with few differences. The mean skull length (SL), skull height (SH), distance between two supraorbital foramina (DBTSF), orbital length (OL), mandible length (ML) and Sharri sheep diastema (D) were 247.47 ± 13.12 mm, 104.71 ± 6.21 mm, 50.73 ± 3.44 mm, 41.21 ± 1.99 mm, 185.91 ± 13.33 mm and 45.81 ± 3.73 mm, respectively. The results also show that out of 51 parameters, only 13 show a statistically significant difference between females and males, particularly the distance of akrokranion to opisthion (AO), articular surface length of mandibular condyle (ASL) and anterior limit of the mandibular foramen to cranial border of ramus mandible (RBMFRMRM). The findings of this study are important in many aspects: morphologically, morphometrically and especially clinically, during surgical interventions in the head region. With a lack of information in current literature on the investigated parameters in this sheep breed, the present data are a solid basis for further studies in comparative anatomy with other ruminants and in other areas such as zooarchaeology and animal welfare.

Sex and Age Determination by Measurement of Foramen Magnum Dimensions on Computer Tomography Scanning Study in the Iranian Population

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.

Three-dimensional geometric morphometric studies of modern human occipital variation

Objectives

To investigate three-dimensional morphological variation of the occipital bone between sexes and among populations, to determine how ancestry, sex and size account for occipital shape variation and to describe the exact forms by which the differences are expressed.

Methods

CT data for 214 modern crania of Asian, African and European ancestry were compared using 3D geometric morphometrics and multivariate statistics, including principal component analysis, Hotelling’s T² test, multivariate regression, ANOVA, and MANCOVA.

Results

Sex differences in average occipital morphology are only observed in Europeans, with males exhibiting a pronounced inion. Significant ancestral differences are observed among all samples and are shared by males and females. Asian and African crania have smaller biasterionic breadths and flatter clivus angles compared to Europeans. Asian and European crania are similar in their nuchal and occipital plane proportions, nuchal and occipital angles, and lower inion positions compared to Africans. Centroid size significantly differs between sexes and among populations. The overall allometry, while significant, explains little of the shape variation. Larger occipital bones were associated with a more curved occipital plane, a pronounced inion, a narrower biasterionic breadth, a more flexed clivus, and a lower and relatively smaller foramen magnum.

Conclusions

Although significant shape differences were observed among populations, it is not recommended to use occipital morphology in sex or population estimation as both factors explained little of the observed variance. Other factors, relating to function and the environment, are suggested to be greater contributors to occipital variation. For the same reason, it is also not recommended to use the occiput in phylogenetic studies.

Cone-beam computed tomography a reliable tool for morphometric analysis of the foramen magnum and a boon for forensic odontologists

Background/Aim:

The aim of this pilot study was to perform morphometric analysis of the foramen magnum (FM) using cone-beam computed tomography (CBCT).

Materials and Methods:

This study included CBCT images of 120 individuals (60 males and 60 females). The sagittal and transverse diameters and circumference of the FM were measured. The data were statistically analyzed with Chi-square and t-tests to assess the level of significance for sex and age.

Results:

The means of its sagittal and transverse diameters and also circumference were higher in males than in females. Statistically significant differences were found between transverse and circumference in case of males and females for all variables (P < 0.05). No statistically significant difference (P > 0.05) was found in sagittal diameter and age groups for all variables.

Conclusion:

CBCT images can provide valuable information regarding FM and the measurements of its sagittal and transvers diameters and also its circumference may be reliably used for sexual dimorphism in anthropometric analysis and forensic medicine.

Sex estimation from foramen magnum parameters in adult Turkish population: A computed tomography study

Identification of skeletal relics is crucial for medicolegal purposes. Sex estimation is one of the critical parts providing the identification of skeletal relics. In forensic practice, sex estimation requires multidisciplinary studies of such as forensic medicine, anatomy, dentistry and radiology. Recently, radiological studies on this subject have been increasing with the developing technology. The objective of this study is to examine the usage of radiological dimensions of foramen magnum for sex estimation in human skulls by developing discriminant functions in Turkish population. We analyzed 600 (300 males and 300 females) Computerized Tomography (CT) images of Turkish individuals aged between 21 and 50. Four measurements were obtained from CT images. All measurements in males were significantly greater than in females, and they provided the higher sex classification accuracy. The area of the foramen magnum calculated by Radinsky's formula was the best measurement for sex estimation with a 75% accuracy rate. In conclusion, the CT images of foramen magnum show sexual dimorphism in our population. To use population specific data would be the most appropriate approach for sex estimation.

Cervico-medullary compression ratio: A novel radiological parameter correlating with clinical severity in Chiari type 1 malformation

OBJECTIVES

Chiari malformation type 1 (CM-1) is associated with cough headache, intracranial hypertension, cerebellar and spinal cord symptoms/signs. Herniated cerebellar tonsil length (HCTL) is widely used radiological parameter to determine the severity of CM-1, but with limited utility due to its weak correlation with some clinico-radiological findings. In this study, we aimed to evaluate a novel, practical parameter (cervico-medullary compression ratio; "CMCR") for its relationship with clinico-radiological findings in CM-1.

PATIENTS AND METHODS

Thirty-five adult patients (17 F, 18 M) with CM-1 were included in this retrospective study. Head CT and craniospinal MR images were assessed. CMCR was calculated as the ratio of herniated cerebellar tonsil surface area to foramen magnum surface area, and HCTL was measured. These two parameters were correlated with clinical and radiological findings.

RESULTS

The mean CMCR was 0.60 ± 0.15 and mean HCTL was 8.91 ± 3.4 mm with no significant difference between gender and age groups for both parameters. For cough headache (0.64 ± 0.14 vs 0.52 ± 0.15, p = 0.043) and syringomyelia (0.67 ± 0.11 vs 0.56 ± 0.16, p = 0.039), only CMCR; for intracranial hypertension (CMCR: 0.64 ± 0.14 vs 0.55 ± 0.16, p = 0.049; HCTL: 9.66 ± 3.59 mm vs 7.79 ± 3.03 mm; p = 0.045) and cerebellar symptoms (CMCR: 0.65 ± 0.14 vs 0.54 ± 0.16, p = 0.048; HCTL: 10.4 ± 3.5 mm vs 7.4 ± 2.8 mm, p = 0.041), both CMCR and HTCL were significantly different between patients with and without respective findings. However, neither CMCR nor HTCL was different between patients with and without spinal cord symptoms and hydrocephalus.

CONCLUSION

CMCR is a superior numerical parameter than HCTL for the assessment of clinical severity in CM-1 cases and needs further validation with larger studies.

Comparison of Three Methods Used for Estimating Area of Foramen Magnum

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.

Morphological and Morphometric Analysis of Foramen Magnum: An Anatomical Aspect

OBJECTIVE

To investigate the detailed morphological and morphometric analysis of foramen magnum (FM) in dry cranii.

METHODS

One hundred fifty skulls of unidentified sex were macroscopically examined and were photographed with Canon 400B (55 mm objective). According to tooth eruption of the skulls, they were accepted as adults. None of the examined skulls showed signs of prior cranial surgery, malformation, or trauma. The evaluated study parameters that were recorded with Vernier caliper in millimeter were as follows: antero-posterior diameter from Basion to Opisthion, transverse diameter (largest distance between the lateral margins of the FM), and the shape of the FM (Fig. 1). The shape of the FM was determined according to FM index that was calculated by dividing antero-posterior diameter by transverse diameter. When FM index was found greater than or equal to 1.2, the foramen was accepted to be oval in shape. Whereas the FM index was found less than 1.2, the foramen was accepted to be round in shape The area of the FM was calculated by using 2 different formulas as described previously by Radinsky (/4 × π × w × h) and Teixeira (π × {(h + w)/4}2), and "π" was accepted as 3.14 in both formulas.

RESULTS

The results of descriptive statistics and areas of the FMs were presented in Table 1. The mean antero-posterior diameter and transverse diameter of anteroposterior diameter by transverse diameters were found as 34.38 ± 2.38 and 28.95 ± 2.19, respectively. The mean area of the FMs estimated by Teixeria formula was determined significantly larger than the mean area of the FMs estimated by Radinsky formula (P <0.001). According to estimated FM index of the 150 adult dry skulls, 87 (58%) of skulls were described as being round in shape and 63 (42%) of skulls were described as being oval in shape (Fig. 1).

CONCLUSION

The surgeons must comprehend regarding the detailed morphological and morphometric features of FM to avoid vital complications during the surgical procedures.

Computed tomographic study of posterior cranial fossa, foramen magnum, and its surgical implications in Chiari malformations

Objective:

The aim of this study is to measure the height and volume of the bony part of the posterior cranial fossa (PCF) and the surface area of the foramen magnum (FM) using computed tomography (CT) scans and to correlate our clinical findings with the available current literature.

Materials and Methods:

This cross-sectional study was conducted in a tertiary care referral hospital in the Southern part of India during the period from January 2015 to August 2015. A total of 100 CT scans of the suspected head injury patients were collected retrospectively form the basis for this study. The height, volume of PCF and the anteroposterior (AP), transverse diameter, and surface area of the FM were measured. The values of all parameters were subjected to statistical analysis using SPSS version 16.

Results:

The age of the patients were ranged between 18 and 70 years with the mean age of 41.22 ± 13.93 years. The dimensions of the posterior fossa and FM were larger in males compared to females. The mean height of the posterior fossa was 38.08 (±4.718) mm (P = 0.0001), and the mean volume of the posterior fossa was 157.23 (±6.700) mm³ (P = 0.0001). The mean AP, transverse diameter, and the surface area of the FM were 33.13 (± 3.286) mm, 29.01 (± 3.081) mm, and 763.803 (±138.276) mm², respectively.

Conclusion:

The normal dimensions of the posterior fossa and FM were less in females than males and were useful to radiologists and neurosurgeons to better their diagnostic inferences, as well as to determine the proper treatment options in Chiari malformation type I (CMI) and other posterior fossa anomalies. The posterior fossa tissue volume can be reliably measured in patients with CMI using our method. More studies were required because there were variations in dimensions among individuals of different races in different regions of the world.

The size and shape of the foramen magnum in man

Background:

The foramen magnum (FM) has garnered broad interest across the disciplines of anthropology, comparative anatomy, evolutionary biology, and clinical sciences. Most studies regarding the structure of the FM in humans have been intrapopulation morphometric studies rather than interpopulation morphologic studies. The few studies assessing the morphology of the foramen have utilized ambiguous and subjective descriptors to describe foraminal shape and are, consequently, difficult to reproduce. Therefore, detailed study of FM shape among craniofacially and geographically diverse populations through reproducible methods is warranted.

Objectives:

The aim of this study was to assess intersex and interpopulation differences in FM size and shape among diverse populations.

Materials and Methods:

The study analyzed 152 FMs of varied sex and race via traditional and geometric morphometric methods.

Results and Conclusions:

The study demonstrates that, within each distinct population, the size of the FM is significantly larger in males than in females; however, there are no significant differences in the shapes of the foramina between sexes. However, when comparing different populations to one another, there are significant differences with regard to both the size and shape of the FM. This study also presents a new model of FM ontogeny. Specifically, the growth occurring between the anterior and posterior foraminal boundaries before 5 years of age predicts the ultimate shape of the adult FM.

Assessment of sex in a modern Turkish population using cranial anthropometric parameters

The utilization of radiological imaging methods in anthropometric studies is being expanded by the application of modern imaging methods, leading to a decrease in costs, a decrease in the time required for analysis and the ability to create three-dimensional images. This retrospective study investigated 400 patients within the 18-45-years age group (mean age: 30.7±11.2years) using cranial computed tomography images. We measured 14 anthropometric parameters (basion-bregma height, basion-prosthion length, maximum cranial length and cranial base lengths, maximum cranial breadth, bizygomatic diameter, upper facial breadth, bimastoid diameter, orbital breadth, orbital length, biorbital breadth, interorbital breadth, foramen magnum breadth and foramen magnum length) of cranial measurements. The intra- and inter-observer repeatability and consistency were good. From the results of logistic regression analysis using morphometric measurements, the most conspicuous measurements in terms of dimorphism were maximum cranial length, bizygomatic diameter, basion-bregma height, and cranial base length. The most dimorphic structure was the bizygomatic diameter with an accuracy rate of 83% in females and 77% in males. In this study, 87.5% of females and 87.0% of males were classified accurately by this model including four parameters with a sensitivity of 91.5% and specificity of 85.0%. In conclusion, CT cranial morphometric analysis may be reliable for the assessment of sex in the Turkish population and is recommended for comparison of data of modern populations with those of former populations. Additionally, cranial morphometric data that we obtained from modern Turkish population may reveal population specific data, which may help current criminal investigations and identification of disaster victims.

Binary Logistic Regression Analysis of Foramen Magnum Dimensions for Sex Determination

Purpose. The structural integrity of foramen magnum is usually preserved in fire accidents and explosions due to its resistant nature and secluded anatomical position and this study attempts to determine its sexing potential. Methods. The sagittal and transverse diameters and area of foramen magnum of seventy-two skulls (41 male and 31 female) from south Indian population were measured. The analysis was done using Student's t-test, linear correlation, histogram, Q-Q plot, and Binary Logistic Regression (BLR) to obtain a model for sex determination. The predicted probabilities of BLR were analysed using Receiver Operating Characteristic (ROC) curve. Result. BLR analysis and ROC curve revealed that the predictability of the dimensions in sexing the crania was 69.6% for sagittal diameter, 66.4% for transverse diameter, and 70.3% for area of foramen. Conclusion. The sexual dimorphism of foramen magnum dimensions is established. However, due to considerable overlapping of male and female values, it is unwise to singularly rely on the foramen measurements. However, considering the high sex predictability percentage of its dimensions in the present study and the studies preceding it, the foramen measurements can be used to supplement other sexing evidence available so as to precisely ascertain the sex of the skeleton.

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

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.

Basicranial analysis in young bovines reveals a relation to breed and sex

The purpose of this article was to examine the level of sexual dimorphism exhibited in the foramen magnum and occipital condyles of bovine juveniles and to test the utility of three basicranial measurements for estimating sex and to evaluate breed differences. Data were taken from 68 bovines of known sex, age and breed. The linear foramen magnum measurements (breadth and height) were not effective in determining the sex of the skulls, but there appeared differences of the occipital bicondylar breadth between sexes and breeds evaluated ('Bruna dels Pirineus' and others). The occipital bicondylar breadth assigned the sex correctly 75% of the cases. The study of occipital bicondylar breadth could thus be effective to obtain reliable results for the determination of sex in bovine skulls and also could be taken into account when differentiating breeds. It is considered that this study will make morphological contributions to develop a comparative model for other domestic bovine breeds, for there is inadequate literature on foramen magnum morphology for domestic species contrary to the richness of these kinds of studies on humans. The results obtained in this study can also be useful as baseline research data in comparative neuroanatomy and in neuropathology. Focusing on zooarchaeology and also on forensic veterinary, simple morphometric analysis of this type can be used as part of an investigative process prior to more sophisticated and expensive analyses such as the DNA examination.

Sexual dimorphism in Brazilian human skulls: discriminant function analysis

Many anthropological studies have shown that sex can be determined using the human skeleton, especially by examining the pelvis and skull. The aim of this study was to verify the presence of sexual dimorphism in the Brazilian population by craniometric analysis; to identify the most reliable measurements and to propose a discriminant function for sex determination. The selected sample was composed of 100 adult skulls, 50 male and 50 female, from Cuiabá city, Mato Grosso State, Brazil. Of all the measurements taken, only the difference between the bi-euryon distances has proven insignificant, while themost dimorphic measure was the bi-zygomatic diameter. A discriminant function was obtained by applying the bi-zygomatic and the basion-lambda measurements, with a confidence level of 72%. The authors concluded that most of the traits analyzed are sexually dimorphic and the discriminant function elaborated is reliable for sex determination in human identification for forensic purposes.