Virtual reconstruction and geometric morphometric analysis of the Kocabas hominin fossil from Turkey: Implications for taxonomy and evolutionary significance.

The Kocabas specimen comes from a travertine quarry near the homonymous village in the Denizli basin (Turkey). The specimen comprises three main fragments: portions of the right and left parietal and left and right parts of the frontal bone. The fossil was assumed to belong to the Homo erectus s.l. hypodigm by some authors, whereas others see similarities with Middle Pleistocene fossils (Broken Hill 1/Kabwe, Bodo, or Ceprano). Here, we present the first attempt to make a complete reconstruction of the missing medial portion of the frontal bone and a comprehensive geometric morphometric analysis of this bone. We restored the calotte by aligning and mirroring the three preserved fragments. Afterward, we restored the missing portion by applying the thin-plate spline interpolation algorithm of target fossils onto the reconstructed Kocabas specimen. For the geometric morphometric analyses, we collected 80 landmarks on the frontal bone (11 osteometric points, 14 bilateral curve semilandmarks, and 41 surface semilandmarks). The comparative sample includes 21 fossils from different chronological periods and geographical areas and 30 adult modern humans from different populations. Shape analyses highlighted the presence in Kocabas of features usually related to Middle Pleistocene Homo, such as a developed supraorbital torus associated with a relatively short frontal squama and reduced post-toral sulcus. Cluster analysis and linear discriminant analysis classification procedure suggest Kocabas being part of the same taxonomic unit of Eurasian and African Middle Pleistocene Homo. In light of our results, we consider that attributing the Kocabas hominin to H. erectus s.l. may be unwarranted. Results of our analyses are compatible with different evolutionary scenarios, but a more precise chronological framework is needed for a thorough discussion of the evolutionary significance of this specimen. Future work should clarify its geological age, given uncertainties regarding its stratigraphic provenance.

The influence of biological relatedness on sexual dimorphism and sex classification based on external morphology of the frontal bone.

The most significant sexual differences in the human skull are located in the upper third of the face (the frontal bone), which is a useful research object, mainly in combination with virtual anthropology methods. However, the influence of biological relatedness on sexual dimorphism and frontal bone variability remains unknown. This study was directed at sexual difference description and sex classification using the form and shape of the external surface of the frontal bones from a genealogically documented Central European osteological sample (nineteenth to twentieth centuries). The study sample consisted of 47 cranial CT images of the adult members of several branches of one family group over 4 generations. Three-dimensional virtual models of the frontal bones were analyzed using geometric morphometrics and multidimensional statistics. Almost the entire external frontal surface was significantly different between males and females, especially in form. Significant differences were also found between this related sample and an unrelated one. Sex estimation of the biologically related individuals was performed using the classification models developed on a sample of unrelated individuals from the recent Czech population (Cechová et al. in Int J Legal Med 133: 1285 1294, 2019), with a result of 74.46% and 63.83% in form and shape, respectively. Failure of this classifier was caused by the existence of typical traits found in the biologically related sample different from the usual manifestation of sexual dimorphism. This can be explained as due to the increased degree of similarity and the reduction of variability in biologically related individuals. The results show the importance of testing previously published methods on genealogical data.

Sex estimation through geometric morphometric analysis of the frontal bone: an assessment in pre-pubertal and post-pubertal modern Spanish population.

Sex estimates is a key step of biological profile assessment in a forensic or anthropologic context. In this study, the sexual dimorphism of the frontal bone was analyzed to assess the accuracy of sex estimates using a geometric morphometric approach in a pre-pubertal and post-pubertal sample. The shape of the frontal bone was digitized on the lateral cephalograms of 87 pre-pubertal subjects (42 males, mean age 10.14, SD ± 1.48 years; 45 females mean age 10.02, SD ± 1.11 years) and 103 post-pubertal ones (53 males, mean age 29.33 SD ± 11.88 years; 50 females, mean age 26.77 SD ± 11.07 years). A generalized Procrustes analysis (GPA) was performed for shape analyses, filtering the effects of position, rotation, translation, and size. A principal component analysis (PCA) was performed on the GPA transformed variables, and a multiple logistic regression model was used to assess the accuracy of sex estimates. In both age groups, the average size of the centroid was significantly larger in males. The females presented shapes with a shorter distance between P2 (glabella) and P1 (supratoral) and a general narrowing of the structure on the sagittal plane. In the pre-pubertal group, the shape difference was not statistically significant. In the post-pubertal group, the mean shape was significantly different between the sexes. The method displayed a high accuracy for sex estimates (88.7% males, 90.3% females) also when applied in a validation sample (82.6% males and 94.1% females). The described morphometric analysis of the frontal bone is based on a limited number of landmarks, which allows sex estimates with high accuracy in post-pubertal subjects, while it is not applicable in pre-pubertal ones.

A geometric morphometric approach to the study of sexual dimorphism in the modern human frontal bone.

OBJECTIVES: We analyzed the main anatomical traits found in the human frontal bone by using a geometric morphometric approach. The objectives of this study are to explore how the frontal bone morphology varies between the sexes and to detect which part of the frontal bone are sexually dimorphic. MATERIALS AND METHODS: The sample is composed of 161 skulls of European and North American individuals of known sex. For each cranium, we collected 3D landmarks and semilandmarks on the frontal bone, to examine the entire morphology and separate modules (frontal squama, supraorbital ridges, glabellar region, temporal lines, and mid-sagittal profile). We used Procrustes ANOVAs and LDAs (linear discriminant analyses) to evaluate the relation between frontal bone morphology and sexual dimorphism and to calculate precision and accuracy in the classification of sex. RESULTS: All the frontal bone traits are influenced by sexual dimorphism, though each in a different manner. Variation in shape and size differs between the sexes, and this study confirmed that the supraorbital ridges and glabella are the most important regions for sex determination, although there is no covariation between them. The variable size does not contribute significantly to the discrimination between sexes. Thanks to a geometric morphometric analysis, it was found that the size variable is not an important element for the determination of sex in the frontal bone. CONCLUSION: The usage of geometric morphometrics in analyzing the frontal bone has led to new knowledge on the morphological variations due to sexual dimorphism. The proposed protocol permits to quantify morphological covariation between modules, to calculate the shape variations related to sexual dimorphism including or omitting the variable size.

Hyperostosis frontalis interna and frontal bone thickness among various age groups - differences between males and females.

Hyperostosis frontalis interna (HFI) represents an abnormality of the frontal cranial bone that is characterized by bilateral, nodular thickening of its inner lamina and may sometimes be associated with neuropsychiatric symptoms such as headaches and depression. The aim was to assess prevalence, sex and age differences of HFI and frontal bone thickness by means of MRI. This retrospective study included 908 subjects who were divided into male and female groups and further subdivided into three groups, youngest (≤45 years), middle-aged (46- 65 years) and the oldest group (65 years). The thickness of the frontal bone was measured on the T2-weighted axial images at the top level of the lateral ventricles as a mean from both sides. We considered 10mm or thicker frontal bone as HFI. The total prevalence of HFI was 8.1%, with a more frequent occurrence in women (p0.05). In males, there was no difference in the frontal bone thickness between different age groups (p0.05), while in females we found differences between the youngest and the oldest group, and also between the middle-aged and the oldest group (p0.05). The female respondents had a thicker frontal bone, which was statistically significant only in the oldest group (p0.001). Frontal bone thickness was age-dependent only in women (Spearman's Rho 0.11; p≤0.01). In women, unlike in men, there is an age-related progression of HFI with increasing prevalence, with 16.4% occurrence in the oldest group.

Sex estimation using external morphology of the frontal bone and frontal sinuses in a contemporary Czech population.

Sex estimation is a task of utmost importance in forensic anthropology and bioarcheology. Along with the pelvic bone, the skull is the most important source of sexual dimorphism. On the human skull, the upper third of the face (i.e., the frontal bone) is one of the most significant sexually dimorphic structures useful in anthropological research, especially when studied by methods of virtual anthropology. This study was focused on sex estimation using the form and shape of the external surface of the frontal bone with or without the inclusion of its sinuses. The study sample consisted of 103 cranial CT images from a contemporary Czech population. Three-dimensional virtual models of the frontal bones and sinuses were analyzed using geometric morphometrics and multidimensional statistics: coherent point drift-dense correspondence analysis (CPD-DCA), principal component analysis (PCA), and support vector machine (SVM). The whole external frontal surface was significantly different between males and females both in form and shape. The greatest total success rate of sex estimation based on form was 93.2%, which decreased to 86.41% after crossvalidation, and this model identified females and males with the same accuracy. The best estimation based on shape reached a success rate of 91.26%, with slightly greater accuracy for females. After crossvalidation, however, the success rate decreased to 83.49%. The differences between sexes were significant also in the volume and surface of the frontal sinuses, but the sex estimation had only 64.07% accuracy after crossvalidation. Simultaneous use of the shape of the frontal surface and the frontal sinuses improved the total success rate to 98.05%, which decreased to 84.46% after crossvalidation.

Anatomical Variations of the Supraorbital and Supratrochlear Nerves: Their Intraorbital Course and Relation to the Supraorbital Margin.

BACKGROUND This study aimed to describe the topographical anatomy of the supraorbital and supratrochlear nerves. Anatomical variations of both the intraorbital course of the 2 nerves and their relation to the supraorbital margin were analyzed. MATERIAL AND METHODS The research material involved 50 isolated adult cadaveric hemi-heads and 25 macerated adult skulls. All studied specimens were of Caucasian origin. RESULTS Taking into account the location of the frontal nerve division, 2 main variants of the intraorbital course of the supraorbital and supratrochlear nerves were distinguished. The first variant (variant I, 42%) involved cases in which the supraorbital and supratrochlear nerves branched off from the frontal nerve in the distal half of the length of the orbit. In the second variant (variant II, 58%), the frontal nerve branched into the supraorbital and supratrochlear nerves in the proximal half of the orbit. Variant II was characterized by the presence of a thick supraorbital nerve and a long, tiny supratrochlear nerve. For variant I, 27.8% of the supraorbital nerves were divided into the medial and lateral branch within the orbit, whereas, for variant II, 75% of nerves were divided into the medial and lateral branch within the orbit (before crossing the supraorbital margin). Single passage was observed on the supraorbital margin in 80% of wet specimens and in 78% of orbits examined on the macerated skulls. CONCLUSIONS Both the intraorbital and extraorbital course of the branches of the supraorbital and supratrochlear nerves were highly diverse. These variations should be taken into account during medical procedures performed within the orbital and frontal regions.

Incidence of anatomical variations according to the International Frontal Sinus Anatomy Classification (IFAC) and their coincidence with radiological sings of opacification.

BACKGROUND: The endonasal access to the frontal recess and sinus may be complicated by a variety of anatomical variations. Previous classifications of these variants were characterized by proper names or position information without anatomical reference. The IFAC is intended to simplify the classification of anatomical variations of the frontoethmoidal complex. The aim of this study was to analyse a representative number of sinus CT scans to assess the incidence of anatomical variations according to the IFAC and to compare the results with previous classifications. In addition, the coincidence of complex anatomical variations and radiological sings of opacification was investigated. METHODOLOGY/PRINCIPAL: Two hundred and forty-nine sinus CT scans were analysed in multiplanar reconstructions. Exclusion criteria were previous operations on the paranasal sinuses, malignant diseases, and an insufficient image quality. All anatomical variants were analysed according to the IFAC criteria. In addition, the coincidence of radiological sings of opacification and the presence of anatomical variations of the frontal recess and sinus were investigated. RESULTS: The analysis revealed Agger nasi cells in 95% of the CT scans. Supra agger cells (SACs) were detected in 49% and Supra agger frontal cells (SAFCs) in 25% of the data sets. Suprabulla cells (SBCs) were detected in 89% and Supra bulla frontal cells (SBFCs) in 27% of the scans. Supraorbital ethmoid cells (SECs) were detectable in 9% and interfrontal septal cells in 28% of the scans. Despite a partially strong narrowing of the frontal recess, no increased occurrence of radiological sings of opacification could be detected (p > 0.05). CONCLUSIONS: Anatomical variations in the frontoethmoidal area are very common. According to the IFAC criteria, in 43% of the patients, cells could be detected with pneumatization to or into the frontal sinus. The IFAC is structured more clearly compared to previous classifications due to the anatomical aspect. It represents the most consistent classification regarding surgical planning. Further studies will demonstrate the scientific and clinical value of this classification.

Age and Gender Differences of the Frontal Bone: A Computed Tomographic (CT)-Based Study.

BACKGROUND: Age-related changes of the frontal bone in both males and females have received limited attention, although understanding these changes is crucial to developing the best surgical and nonsurgical treatment plans for this area. OBJECTIVES: To investigate age-related and gender-related changes of the forehead. METHODS: Cranial computed tomographic images from 157 Caucasian individuals were investigated (10 males and 10 females from each of the following decades: 20-29 years, 30-39 years, 40-49 years, 50-59 years, 60-69 years, 70-79 years, 80-89 years, and of 8 males and 9 females aged 90-98 years). Frontal bone thickness and forehead distance measurements were carried out to analyze age and gender differences. RESULTS: With increasing age, the size of a male forehead reduces until no significant differences to a female forehead is present at old age (P = 0.307). The thickness of the frontal bone of the lower forehead (≤4 cm cranial to the nasal root) increased slightly in both genders with increasing age. In the upper forehead (≥4 cm cranial to the nasal root), frontal bone thickness decreased significantly (P = 0.002) in males but showed no statistically significant change in thickness in females (P = 0.165). CONCLUSIONS: The shape of the frontal bone varies in young individuals of different genders and undergoes complex changes with age because of bone remodeling. Understanding these bony changes, in addition to those in the soft tissues, helps physicians choose the best surgical and nonsurgical treatment options for the forehead.

Demystifying the "Triple Point: " Technical Nuances of the Fronto-Orbital Advancement.

Removal of the fronto-orbital bandeau is one of the most critical components for procedures designed to correct anomalies of the craniofacial skeleton and remodel the anterior calvarial vault. It is also used to improve exposure of the anterior cranial fossa. It is arguably one of the more difficult portions of some craniofacial procedures. While the technique for fronto-orbito-sphenoid osteotomy has been frequently described, it has only been minimally detailed. Separation of bone in this region remains challenging due to the bone thickness, adjacent vital structures, and limited direct visibility. The present paper describes the anatomy of this particular region, which the authors have termed the "triple point", to facilitate successful osteotomy and avoid potential injury.

Anatomy of the Corrugator Muscle.

The aim of this article is to systematically review the anatomy and action of the corrugator muscle. PubMed and Scopus were searched using the terms "corrugator" AND "anatomy." Among the 60 full texts from the 145 relevant abstracts, 34 articles without sufficient content were excluded and 4 articles drawn from the reference lists were added. Among the 30 articles analyzed (721 hemifaces), 28% classified by oblique head and transverse head, and 72% did not. Corrugator originated mostly from the medial supraorbital rim (45%), followed by the medial frontal bone (31%), the medial infraorbital rim (17%), and the upper nasal process (7%). Corrugator extended through the frontalis and orbicularis oculi (41%), only the frontalis (41%), or only the orbicularis oculi (18%). Corrugator ran superolaterally (59%), or laterally (41%). Corrugators inserted mostly to the middle of the eyebrow (57%), or the medial half of the eyebrow (36%), but also to the glabella region (7%). The length of the corrugator ranged 38 to 53 mm. The transverse head (23.38 mm) was longer than the oblique head (19.75 mm). Corrugator was thicker at the medial canthus than at the midpupillary line. Corrugator was innervated by the temporal branch of the facial nerve (66%), the zygomatic branch (17%), or the angular nerve (zygomatic branch and buccal branch, 17%). Supraorbital nerve (60%) or supratrochlear nerve (40%) penetrated the corrugator. The action was depressing, pulling the eyebrow medially (91%), or with medial eyebrow elevation and lateral eyebrow depression (9%). Surgeons must keep this anatomy in mind during surgical procedures.

A Three-dimensional Analysis of Zygomatic Symmetry in Normal, Uninjured Faces.

Current approaches to facial reconstruction are based on the assumption of facial symmetry, though this has yet to be established in the literature. Through quantitative and qualitative analysis, symmetry of normal, male faces is examined here using the zygomatic complex as a bellwether for the rest of the facial skeleton. Three-dimensional models reconstructed from the computed tomography scans of 30 adult male patients displaying normal facial skeletal anatomy were analyzed. Seven zygomatic landmarks were identified on all craniofacial models, and asymmetry scores were calculated based on the average deviation distance upon reflection of 1 hemiface across the midfacial plane. Deviation maps were then generated for each zygomatic pair to enable visualization of the asymmetry. All landmarks displayed a slight (<3 mm) deviation from perfect symmetry, and analysis of zygomatic form asymmetry revealed an average of 0.4 mm of surface deviation between hemifaces. The presence of such slight asymmetries in the zygoma warrants further investigation as to the clinical relevance of such skeletal asymmetries from both an esthetic and biomechanical consideration to provide insight as to the proper approach to zygomatic restoration in cases of zygomatic fracture.

Comparing the left and right Whitnall's tubercles and their relation to the frontozygomatic suture: Application to symmetry following lateral orbital surgery.

We compare, on left and right side of human skulls, the length of Whitnall's tubercle as a relevant landmark and anchor point for the lateral retinaculum. Twenty human skulls were used in this study. A caliper was used to measure the length of Whitnall's tubercle, the distance from Whitnall's tubercle to the frontozygomatic suture and the height of the orbit. An overall mean for these three parameters was calculated using the data obtained. There were no significant differences between left and the right sides. The combined mean length of Whitnall's tubercle was 4.9 mm ± 23%. The combined mean distance from the frontozygomatic suture was 7.8 mm ± 25%. The orbital height was found to be the measurement with the highest congruence between the two sides having a combined mean of 32.3 mm ± 7%. Although 6 out of 20 skulls were found to have no tubercle, five out of twenty skulls had a tubercle only on one side. Even though human skulls develop from bilateral symmetric osteogenesis, surgeons should always be aware of possible asymmetry and possible absence of Whitnall's tubercle between sides or among individuals. The frontozygomatic suture was found to be a useful landmark in identifying the position of Whitnall's tubercle in the majority of specimens. Such information will be useful in realigning the lateral retinaculum following surgery.

Line of Sight in Hominoids.

OBJECTIVES: It remains unclear how the realignments of the face and basicranium that characterize humans were acquired, both phylogenetically and ontogenetically. The developmentally constrained nature of the skull has been previously demonstrated in other primates using Donald H. Enlow's mammalian craniofacial architectural relationships. Here, we compare crania of our closest relatives to gain greater understanding of how and why the relationship of the face and cranial base is developmentally constrained in order to inform instances of abnormal growth and clinical intervention. STUDY DESIGN: A method for evaluating these fundamental architectural relationships using 3D landmark data was developed, thereby taking overall size and the geometric relationships among points into account. A sample of cone-beam computed tomography scans derived from humans and extant apes were analyzed (n=10 and n=6, respectively), as well as fossil hominid crania (n=7). Landmarks for 23 craniofacial architectural points were identified and recorded. RESULTS AND CONCLUSIONS: Principal components analyses reveal that despite the similarities in craniofacial architecture between humans, extant apes and fossil hominids, appreciable trends in variation between the extant species suggest that the repositioning of the foramen magnum was only one of a constellation of traits that realigned the basicranium and face during the transition to bipedalism.

Morphological relationship between the cranial and supraorbital regions in Homo sapiens.

Although some hypotheses that attempt to explain the variation in supraorbital region morphology in modern humans have been proposed, this issue is still not well understood. In this study, the craniofacial size and spatial models were tested using a sample of modern human crania from geographically diverse populations, and the co-occurrence of the degrees of glabella (GL) and superciliary arch (ST) expression were analyzed. The two supraorbital structures were examined by visual assessment, and eight quantitative variables were included in the three-way ANOVA, canonical variates analysis and partial rank correlation. The influences of sex and the region of origin of the cranial samples on the relationships between the examined variables and the degrees of supraorbital structures expression were also considered. The results only partially supported the craniofacial size and spatial models and suggested that GL and ST experienced separate influences during development. In the sample of all crania, the neurocranial size more strongly influenced the morphological variation of the ST than of the GL, and sex influenced both of these structures the most. The results suggest that sex may be the main factor (having an influence independent of the other traits) on the morphological variation of the GL and ST.

The Incidence and Topographic Distribution of Sutures Including Wormian Bones in Human Skulls.

OBJECTIVE: The Wormian Bones are accessory bones located within the cranial sutures and fontanelles. The present article examines the incidence of Wormian Bones and compares the number and topographic distribution between the sutures including Wormian Bones in skulls of West Anatolian Population. METHODS: One hundred fifty crania were examined. The parameters evaluated in the present study were as follows: the rate of skulls including Wormian Bones; the topographic distribution and frequencies of the sutures including Wormian Bones; the number of these sutures for each skull; the name and number of sutures that were bilaterally and symmetrically located on the right and left side of skull (paired sutures) and which coincidentally had Wormian Bones for each skull; the differences of frequencies between the paired sutures including Wormian Bones. RESULTS: The rate of skulls including Wormian Bones was determined as 59.3%. The maximum and minimum numbers of sutures, including Wormian Bones, were 6 in 1 skull and 1 in each of 30 skulls, respectively. The maximum and minimum rates of sutures that had Wormian Bones were found in left lambdoid 40.7% and right occipitomastoid 1.3% sutures, respectively. There was only a significant difference between the rate of right and left squamous sutures (P = 0.04). Forty-five skulls were including 55 pairs of bilaterally and symmetrically located sutures that coincidentally had Wormian Bones in each pair. Each of 35 skulls had 1 pair of sutures including Wormian Bones and each of 10 skulls had 2 pairs. CONCLUSIONS: In the present study, the rate of Wormian Bones was determined as 59.3% in West Anatolian Population. This incidence rate is considerably lower than the other reports, and it may be as a result of racial variations. These divergent bones were more frequently found in left lambdoid sutures (40.7%) and less frequently in right occipitomastoid sutures (1.3%). This study may guide the investigators dealing with the neurosurgery, orthopedy, radiology, anatomy, and anthropology in their practice.

Where to fix in rejuvenation surgeries?: tensile strength of the periosteum.

The aim of this study is to elucidate the tensile strength of the periosteum relating to facial rejuvenation surgeries.Twelve hemifaces of 6 formalin-fixed Korean adult cadavers were used. Two horizontal incision lines were made 3 cm above the supraorbital rim and 1 cm below the infraorbital rim. Another 2 vertical incisions were on the medial orbital rim and 2 cm lateral to the lateral orbital rim. Elevated flaps were turned over, and the undersurfaces of the periosteum were exposed. A silk string was passed below the periosteum with a 3-mm bite and wound. A 3-cm loop was made, and this was pulled away using the tensiometer. The breaking strength was measured.The breaking strengths of the periosteum were different according to the location (P = 0.000, analysis of variation). The strongest point was 2 cm above the supraorbital rim at the medial one third of the orbit (14.05 [2.50] N) followed by 1 cm above the frontozygomatic suture (13.35 [4.70] N). The weakest point was the infraorbital rim at the lateral one third of the orbit (6.93 [3.76] N) followed by the lateral orbital rim at the level of the lateral canthus (7.60 [3.49] N). Breaking strengths of the periosteum of the medial side (11.44 [3.83] N) were significantly greater (P = 0.021, t-test) than the lateral side (9.32 [3.76] N). In the supraorbital area, the breaking strengths of the periosteum of the upper points (12.91 [3.00] N) were significantly greater (P = 0.000, t-test) than the lower points (9.36 [2.76] N).The results of this study can be of use when choosing a fixation point in rejuvenation surgeries.

Application of a Novel Semi-Automatic Technique for Determining the Bilateral Symmetry Plane of the Facial Skeleton of Normal Adult Males.

The accurate assessment of symmetry in the craniofacial skeleton is important for cosmetic and reconstructive craniofacial surgery. Although there have been several published attempts to develop an accurate system for determining the correct plane of symmetry, all are inaccurate and time consuming. Here, the authors applied a novel semi-automatic method for the calculation of craniofacial symmetry, based on principal component analysis and iterative corrective point computation, to a large sample of normal adult male facial computerized tomography scans obtained clinically (n = 32). The authors hypothesized that this method would generate planes of symmetry that would result in less error when one side of the face was compared to the other than a symmetry plane generated using a plane defined by cephalometric landmarks. When a three-dimensional model of one side of the face was reflected across the semi-automatic plane of symmetry there was less error than when reflected across the cephalometric plane. The semi-automatic plane was also more accurate when the locations of bilateral cephalometric landmarks (eg, frontozygomatic sutures) were compared across the face. The authors conclude that this method allows for accurate and fast measurements of craniofacial symmetry. This has important implications for studying the development of the facial skeleton, and clinical application for reconstruction.

Brief communication: The size of the human frontal sinuses in adults presenting complete persistence of the metopic suture.

The notion of absence of the frontal sinuses in human individuals presenting a persistence of the metopic suture is considered as classical in many treatises of reference; however, precise studies are very rare and even controversial. The purpose of this study was thus to provide original data to confirm or refute this classical affirmation with the perspective of some original insights into biological significance of the frontal sinuses and the factors influencing their exceptional polymorphism. The material consisted of 143 dry skulls of adult individuals (European Homo sapiens), distributed in two groups: 80 skulls presenting a complete frontal closure with total disappearance of the metopic suture, and 63 skulls presenting a complete persistence of the metopic suture. Each skull was radiographed in oblique projection using the occipitomental view. A simple morphological quantification of the sinus size was defined with four categories: (1) aplasia, (2) hypoplasia, (3) medium size, (4) hyperplasia. Statistically significant difference in frontal sinusal size was found between both groups of skulls. Absent and small sinuses were considerably more frequent in skulls with persistence of the metopic suture (57.9 vs. 11.9%): small frontal sinuses (hypoplasia) were much more frequent (50.8 vs. 9.4%), although the frequency of absence of frontal sinuses (aplasia) was only slightly higher (7.1 vs. 2.5%).

Morphology and morphometry of the meningo-orbital foramen as a result of plastic responses to the ambient temperature and its clinical relevance.

The meningo-orbital foramen (FMO) is an osteal opening, containing vessels providing an accessory blood supply to the orbit, situated close to the superior orbital fissure. Recent studies show FMO to be ubiquitous, with localization and occurrence varying, depending on a population, what may be due to environmental conditions (ie, temperature). It is often located near the operating area in surgeries in the orbital cavity, and its accurate localization allows avoiding unexpected bleeding during intervention. Because there is a lack of clarity in the literature concerning the morphology and the morphometry of the FMO, this study aimed to clarify the issue with clinical relevance. We studied dry adult human skulls (50 men and 33 women). The morphology and minimal distances between the FMO and standard anthropologic landmarks (nasion, frontomalare orbitale, supraorbital foramen, and zygomaticomaxillary suture) were measured, using MicroScribe G2L, a three-dimensional contact scanner. We compared the result with results of previous studies on populations from various climate zones. The FMO was present in 69.88% of the skulls (56.02% of orbits): in 60.34% of the skulls, the FMO was bilateral; and in 39.66%, unilateral. We observed 74 single, 10 double, and 2 triple foramina. The FMO was present mostly on the sphenoid and the frontal bone. There was no difference in minimal distances between the FMO and the anthropologic landmarks, depending on sex, except the distance to the nasion (shorter in women). The occurrence of the FMO in the population differed from that of other populations. The results show that it is possible that the morphology and the morphometry of the FMO depend on the climate zone or ambient temperature during growth, which should be considered before performing surgery in the orbital cavity.