Transverse Diameter Of Foramen Magnum Research Articles

Determination of Sexual Dimorphism from Foramen Magnum in an Eastern Indian Population

Human identification is an important arena of forensic investigation, it includes sex determination which becomes extremely difficult in fragmented skeletal remains. Skull dimensions are measured for the purpose of sexual dimorphism which vary in different populations. In this study, we attempted to analyse the measurements from adult human skulls and employ discriminant function to predict sex accurately. A manual vernier calliper was used to measure the antero-posterior (AP) diameter and transverse diameter of foramen magnum of 88 skulls (49 males, 39 females) from the collection housed at the department of Anatomy, RG KAR medical college and Calcutta medical college. The Wilk's lambda for the model is 0.795. The discriminant function equation is, Df= 3.342× (APdiameter of foramen magnum) +0.725× (Transverse diameter of foramen magnum) -13.641(constant). The cut-off point is 0.505. So above this value 0.505, the cases are male and below it, the cases are female. On comparing the measurements, we found that antero-posterior dimensions and transverse dimensions of foramen magnum were greater in males than females. Collectively, all the results indicate that dimensions of foramen magnum can be used as a moderate indicator for sex determination in regional populations.

A golden ratio for foramen magnum: an anatomical pilot study.

The foramen magnum (FM) is an important landmark because of its close relationship to key structures such as the brainstem and spinal cord, an extension of the medulla oblongata. Because of the similarity in their shape, the existence of a relationship between cranial length and anteroposterior diameter of the FM, and between cranial width and transverse diameter of the FM may reveal the magnificent harmony of the skull and FM. Based on this idea, we investigated the existence of this harmony in skulls that we used in our study. In this study, 60 adult dry skulls belonging to the Turkish population were examined. The anteroposterior and transverse diameters of the foramen magnum and the length and width of the skull were measured. Measurements were made directly on the skull using a digital sliding calliper. New indices and ratios were applied with those measurements. Our study suggests that FM width and FM length could be estimated by using the cranial length and cranial width measurements in the skull by accepting the mean of these coefficients (4.62) as the golden ratio. The average of the coefficients of cranial width to FM width ratio (4.62 ± 0.35 [95% CI: 4.52-4.70]) and the average of the coefficients of cranial length to the FM length ratio (4.62 ± 0.50 [95% CI: 4.49-4.76]) were found to be equal to each other. In order to check the accuracy of this hypothesis, FM width and FM lengths were estimated with the help of new equations. In the present study, the ratio between the anteroposterior and transverse diameters of both FM and the cranium was estimated at 4.62, indicating a magnificent harmony between cranial and subcranial structures. With this ratio, it is easy to estimate FM's size based on simple cranial measurements.

MORPHOLOGICAL AND MORPHOMETRIC STUDY OF FORAMEN MAGNUM IN DRIED HUMAN SKULL BONES OF NORTH-WEST INDIAN REGION

Background: The Foramen Magnum is communication between vertebral canal and posterior cranial fossa and important landmark to key structures such as brain, spinal cord, vertebral arteries. Anatomical knowledge of the foramen magnum is significant for understanding the pathophysiology of various disorders of the craniovertebral junction as well as for planning surgical procedures. Materials and Methods: The study was conducted on 62 dry skulls of unknown gender obtained from the Department of Anatomy. The shape of foramen magnum was classified as oval, round, tetragonal, pentagonal, hexagonal and irregular in shape and measurements like anterio-posterior diameter and transverse diameter of foramen magnum were taken using the Digital Vernier sliding caliper. Results: In the present study most common shape was oval in 22 (35.48%) skulls, followed by Egg shape in 12 (19.35%) skulls and least common pentagonal shape in 1(1.61%) skulls. In our study the mean anteroposterior diameter was 34.17 mm. and mean transverse diameter was observed to be 28.86 mm. Conclusion: Results of our present study may help in neurosurgeons, orthopedicians, radiologist and anesthetist in North West indian population. KEY WORDS: foramen magnum, skull, transverse diameter, oval.

Sexual dimorphism of foramen magnum: a NCCT based study

<p class="abstract"><strong>Background:</strong> 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.<strong> </strong>The objective of the study was<strong> </strong>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.</p><p class="abstract"><strong>Methods:</strong> 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.</p><p class="abstract"><strong>Results:</strong> 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).</p><p class="abstract"><strong>Conclusions: </strong>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><p class="abstract"> </p>

MORPHOMETRIC ANALYSIS OF FORAMEN MAGNUM IN NORTH INDIAN POPULATION

Introduction: Foramen magnum is a large opening located in the occipital bone of the skull. The morphometric analysis of foramen magnum is clinically and surgically important because vital structures passing through it may suffer compression such as in cases of achondroplasia, brain herniation and meningiomas. Objectives: To study morphometric analysis of foramen magnum in dry human skulls and to measure its anteroposterior diameter, transverse diameter and foramen magnum index. Material & Methods: 100 dried human skulls of unknown age and sex were obtained from Department of Anatomy, Rama Medical College and GSVM Medical College, Kanpur, Uttar Pradesh, India. Deformed samples were excluded. Different parameters were measured with the help of Vernier caliper. Results: The mean antero-posterior diameter of foramen magnum was 33.79mm. The maximum antero-posterior diameter of foramen magnum was 40mm and minimum antero-posterior diameter was 28.2mm.The mean transverse diameter of foramen magnum was 28.30mm.The maximum transverse diameter of foramen magnum was 36mm and minimum transverse diameter was 21.5mm.The mean index of foramen magnum was 84.14mm. Conclusion: The morphometric analysis of foramen magnum and its variation is important not only for anatomists but also important to the anesthetists, neurosurgeons, orthopedicians and radiologists ; while planning and performing cranio-vertebral junction procedures.

Morphometrie study of foramen magnum in human dry skulls

Abstract Background : Anthropologists are often faced with the task of assigning sex to remains that are incomplete, fragmented or damaged as may result from incidents such as mass disasters, airplane crashes, fire, explosions or physical violence. The size of foramen magnum does not change after puberty, not related to age then after. It is this part of the cranial base which can withstand fire explosions as the area is covered by large amount of soft tissue. Hence the foramen magnum was considered for studying the sexual differences in skull. Aims : To analyse the morphology and morphometry of foramen magnum, and the impact of these variables on sex determination of skull. Materials and Methods : 68 male and 68 female adult dry skulls were used for the study. The shapes of foramen magnum were studied. Results : In total, oval was the most common shape comprising of 61.76%, 16.17% arrow head, 11.76% irregular and 10.29% round. The sagittal diameter was 33.0 [28-40] mm in males and 33.0 [28-43] in females and transverse diameters of foramen magnum were 27[21-31] in males and 26.0[23-33]mm in females. Area of foramen magnum was calculated using Radinsky and Teixeria formulae and foramen magnum index was calculated. Mean, standard deviation and median [where ever required] were calculated. Student t test and Mann Whitney U test/ T test were applied. We did not find significant difference between male and female values. Conclusion : Our study did not demonstrate statistically significant difference in expression of sexual differences in the foramen magnum. However if detailed analysis is done with greater sample size by discriminant function analysis, it may prove useful in predicting sex in severely fragmented cranial bases.

Morphometric Study of Foramen Magnum and Variation in Its Shape

Introduction: Foramen magnum plays an important role as a landmark in the region of skull and spine because it transmits key structures like the lower end of the medulla oblongata, meninges, vertebral arteries and the spinal accessory nerve. Aims and objectives: Our aim was to provide basic osteometric data of anteroposterior and transverse diameters of foramen magnum and to observe its different shapes. Materials and methods: Thirty Four (34) adult human skulls of unknown sex were obtained from Department of Anatomy, RIMS, Ranchi. Foramen magnum diameters were calculated using sliding vernier calipers and shapes were visually assessed. Observations and results: Maximum anteroposterior diameter of foramen magnum was found to be 41.5mm and minimum was 28.5mm with the mean of 34.06mm whereas Maximum transverse diameter was 35mm and minimum was 22mm with the mean of 27.83mm. Percentage of foramen magnum shapes were as follows: oval 58.8%, Tetragonal 17.6%, hexagonal 11.8%, circular 8.82% and irregular 2.94% cases. Conclusion: Knowledge of dimensions of foramen magnum is important for radiologist, orthopaedicians and neurosurgeons, while planning and performing cranio-vertebral junction surgeries.

Analysis of morphology of foramen magnum in Indian population

IntroductionThe foramen magnum is a unique and complex neuroanatomical structure. This is an important landmark of the skull base for neurosurgical procedures. The aim of this study is to analyze the morphometry pertaining to variations of the shapes and sizes of foramen magnum separately for males and females of Indian population along with comparing antero-posterior and transverse diameters available in literature and to bring out associated clinical implications. MethodsThirty-five dry skulls (13 females and 22 males) have been examined for morphometric variations of foramen magnum. The surface area of foramen magnum was calculated manually using graphical method. The importance of morphometry and clinical significance of foramen magnum has been established by available literature. ResultsMean antero-posterior diameter and transverse diameter of foramen magnum are 33.8±02.5mm and 28.2±02.6mm, respectively. The minimum, maximum and mean areas of foramen magnum in assorted skulls are 434mm2, 902mm2 and 648.5±112.2mm2, respectively. Foramen magnum index in assorted skulls vary from 1 to 1.45. DiscussionThe dimensions of foramen magnum, separately for males and females in the Indian population, have been analyzed for the first time. This analysis will be of paramount importance for clinicians in surgical procedures around this region.

Morphology of the foramen magnum in syndromic and non-syndromic brachycephaly.

The shape and size of the foramen magnum (FM) can be altered in craniosynostoses. However, few studies have investigated these changes. In this paper, we investigate the morphology of the foramen magnum in syndromic and non-syndromic brachycephaly. Surface area, anteroposterior (AP) diameter, and transverse diameters of the FM were measured on high-resolution CT scans in children with Crouzon (25), Pfeiffer (21), Apert (26), Saethre-Chotzen (7) syndromes, and isolated bicoronal synostosis (9) and compared to an age-matched control group (30). A significantly smaller FM surface area was observed in Crouzon (6.3 ± 1.7cm(2)) and Pfeiffer (6.4 ± 2.3cm(2)) syndromes as compared to the control group (7.4 ± 1.3cm(2), p = 0.006 and p = .017, respectively). In comparison to the control group, no statistically significant alteration in FM surface area was noted in patients with Apert, Saethre-Chotzen, or isolated bicoronal synostosis (p = 0.37, p = 0.71, p = 0.40 respectively). The transverse diameter of FM was significantly smaller in Crouzon, Pfeiffer, and Apert syndromes compared to the control group (p = 0.005, p = 0.002, p = 0.03 respectively). In Saethre-Chotzen and isolated bicoronal synostosis, no difference in transverse diameter was demonstrated. Among all groups, only Crouzon syndrome showed reduced anteroposterior diameter as compared to controls (p = 0.005). In Pfeiffer and Apert syndromes, there was elongation of the shape of the FM with a relatively narrowed width as demonstrated in a significantly increased AP to transverse diameter ratio (p = 0.002 and p = 0.019, respectively). The FM shape and area is significantly altered in fibroblast growth factor receptor (FGFR)-related brachycephaly syndromes (Crouzon, Pfeiffer, and Apert), whereas in patients with Saethre-Chotzen syndrome (TWIST-1 mutation) and isolated non-syndromic bicoronal synostosis, the shape and mean FM area was not statistically different from that of normals. This study brings to light the important role of FGFRs on FM growth and shape. TWIST-1 mutation (Saethre-Chotzen syndrome) does not appear to have an important effect in shaping the FM.

Morphometric Study on Foramen Magnum of Human Skulls

We utilized 100 human skulls to study the morphology and morphometric parameters of the foramen magnum in south Indian population. The anteroposterior diameter and transverse diameter of the foramen magnum were measured by using Vernier calliper to the nearest millimetre. All measurements were tabulated followed by student “t” test and descriptive statistics were done in SPSS version to know the “p” value for the significance. The mean anteroposterior diameter of foramen magnum in males was 3.71 mm and in females it was 3.38 mm. The mean transverse diameter of foramen magnum in males was 3.20 mm and in females it was 3.04 mm. The statistical analysis of morphometry of the foramen magnum in relation to sex determination values are significant (P-Value of Foramen magnum anteroposterior diameter was 0.0001 and transverse diameter was 0.015). Some literatures revealed that anteroposterior diameter of the foramen magnum alone considered for unknown sex determination. Our study reveals significant role of the foramen magnum dimensions in identification of the unknown sex.

An anatomical perspective of human occipital condyles and foramen magnum with neurosurgical correlates

Objectives:Knowledge of condylar anatomy helps the surgeon in making important decisions regarding extent and direction of condylar drilling and minimizing injury and retraction of neural structures. Important preoperative informationincludes length, width, axis/directions and overriding of occipital condyle in foramen magnum, relationships of condyles toforamen magnum and to hypoglossal canal. The anteroposterior and transverse diameters of foramen magnum and amountof overriding of occipital condyle in foramen magnum are useful in calculating area of surgical field. The present study aimsto provide important anatomical parameters for the far lateral transcondylar approach. Methods: The morphometric analysis of human occipital condyles and foramen magnum in 126 dried human skulls and 50separated occipital bones was performed. The parameters significant to the far lateral transcondylar approach were measured using a digital vernier caliper. In addition, morphometric analysis was also done on 40 patients using thin section CTscans. The paired ‘t’test was performed. Results: The difference between the measurements for the right side and left side and those done on CT scans and usingvernier calipers on bones came out to be statistically insignificant (p>0.05). Conclusion:The far lateral transcondylar approach provides better exposure of the ventrolateral foramen magnum and inferior clivus. Lesion removal from this site can be considerably made easier by utilizing a shorter and widened angle of exposure. Preoperative assessment using CT imaging facilitates the far lateral transcondylar approach without damage to vitalfunctional structures

Sex estimation from foramen magnum dimensions in an Indian population

Identification of skeletal remains is vital in forensic investigations. The need for methods to estimate sex from cranial fragments becomes apparent when only a part of skull is brought for identification. The present research is an attempt to study the sexual dimorphism of the anteroposterior diameter, transverse diameter and area of foramen magnum in a population of costal Karnataka region using statistical considerations. Ninety adult dry skulls of known sex (50 male and 40 female) were included in the study. Morphometric analysis of foramen magnum was conducted using vernier calipers and the area of foramen magnum was calculated. The anteroposterior diameter, transverse diameter and area of foramen magnum are found to be significantly larger in males than females. Binary Logistic Regression (BLR) analysis was performed to derive models for estimation of sex from the different measurements of foramen magnum and Receiver Operating Characteristic (ROC) curve was drawn for the predicted probabilities obtained from BLR analysis. The predictability of foramen magnum measurements in sexing of crania was 65.4% for transverse diameter and 86.5% for the anteroposterior diameter. For the area of foramen magnum that was calculated using the formula derived by Radinsky and Teixeria, the predicted probabilities were observed to be 81.6% and 82.2% respectively. When anteroposterior and transverse diameter were used together in BLR analysis the predictability of sex increased to 88%. However, considering the overlapping in the male and female values for the foramen magnum measurements it is suggested that its application in sex estimation should be restricted to cases where only a fragment of base of the skull is brought for examination. In such cases, the anteroposterior diameter and area of the foramen magnum can be employed as better tools for sexing the skulls than the transverse diameter of the foramen magnum.