A model of developmental canalization, applied to human cranial form.

Developmental mechanisms that canalize or compensate perturbations of organismal development (targeted or compensatory growth) are widely considered a prerequisite of individual health and the evolution of complex life, but little is known about the nature of these mechanisms. It is even unclear if and how a "target trajectory" of individual development is encoded in the organism's genetic-developmental system or, instead, emerges as an epiphenomenon. Here we develop a statistical model of developmental canalization based on an extended autoregressive model. We show that under certain assumptions the strength of canalization and the amount of canalized variance in a population can be estimated, or at least approximated, from longitudinal phenotypic measurements, even if the target trajectories are unobserved. We extend this model to multivariate measures and discuss reifications of the ensuing parameter matrix. We apply these approaches to longitudinal geometric morphometric data on human postnatal craniofacial size and shape as well as to the size of the frontal sinuses. Craniofacial size showed strong developmental canalization during the first 5 years of life, leading to a 50% reduction of cross-sectional size variance, followed by a continual increase in variance during puberty. Frontal sinus size, by contrast, did not show any signs of canalization. Total variance of craniofacial shape decreased slightly until about 5 years of age and increased thereafter. However, different features of craniofacial shape showed very different developmental dynamics. Whereas the relative dimensions of the nasopharynx showed strong canalization and a reduction of variance throughout postnatal development, facial orientation continually increased in variance. Some of the signals of canalization may owe to independent variation in developmental timing of cranial components, but our results indicate evolved, partly mechanically induced mechanisms of canalization that ensure properly sized upper airways and facial dimensions.

Digital radiomorphometric analysis of the frontal sinus and assessment of the relation between persistent metopic suture and frontal sinus development.

OBJECTIVES: This study aimed to establish the frequency of the frontal sinus (FS) aplasia, to compare metopic and nonmetopic series and thus to assess the relationship between the preservation of metopic suture and FS development. MATERIALS AND METHODS: FSs were investigated in 230 dry skulls of adult males distributed into control (137) and metopic (93) series. They were visualized through industrial digital radiography. RESULTS: In the control series, the FS aplasia was observed in 12.41% of the skulls, and it was mostly unilateral (8.76%) than bilateral (3.65%). The left-sided aplasia (5.11%) slightly prevailed over the right-sided one (3.65%). In the metopic series, the aplasia was observed with a frequency of 19.35%, and the bilateral aplasia (7.53%) was rarer that the unilateral one (11.83%), while the right-sided aplasia was clearly predominant (9.68%) compared to the left-sided one (2.15%). DISCUSSION: The significant differences between both series showed a tendency for the persistence of metopic suture to be frequently related with FS underdevelopment in the vertical plate of the frontal bone, but in cases of pneumatization, it was preferentially on the left side. Taking into account that the cranial hypertension leads to suture diastasis and hinders development of the FS, it could be suggested that persistence of the metopic suture along with underdevelopment of the FS in nonsyndromic adults could be an expression of an elevated intracranial pressure during early development as an after-effect of certain condition.

The relationship between frontal sinus morphology and skeletal maturation.

BACKGROUND: The aim of this study is to evaluate the relationship between frontal sinus morphology and hand-wrist bone maturation by using postero-anterior (PA) cephalometric radiographs. MATERIALS AND METHODS: The study sample consisted of 220 patients divided into 11 groups based on the hand-wrist radiographs. The right and left maximum height, width and area of the frontal sinus parameters were measured in PA cephalometric radiographs of 220 subjects aged 8-18 years. The hand-wrist skeletal maturation stages were evaluated on the hand-wrist radiographs using the method of Fishman. The Kendall tau-b values were analysed to evaluate the correlation between the hand-wrist skeletal maturation stages and the frontal sinus parameters. RESULTS: The right and left frontal sinus areas and widths were found to be larger in males than in females (p < 0.05). In males, a significant difference was observed in all frontal sinus parameters in different maturation stages (p < 0.001), while a statistically significant correlation was found in females between the left frontal sinus area, right frontal sinus height, right frontal sinus width and different maturation stages (p < 0.05). CONCLUSIONS: The relationship between frontal sinus dimensions obtained from PA cephalometric radiographs and hand-wrist maturation stages suggests that frontal sinuses can be used in determining growth and development.

Association between frontal sinus morphology and cervical vertebral maturation for the assessment of skeletal maturity.

INTRODUCTION: Various methods have been proposed to evaluate a patient's developmental status. However, most of them lacked precision and failed to give a reliable estimate of skeletal maturity. The aims of this study were to evaluate the association between frontal sinus morphology and cervical vertebral maturation for the assessment of skeletal maturity and to determine its validity in assessing the different stages of the adolescent growth spurt. METHODS: A cross-sectional study was performed on the pretreatment lateral cephalograms of 252 subjects aged 8 to 21 years. The sample was divided into 6 groups based on the cervical vertebral maturation stages. The frontal sinus index was calculated by dividing the frontal sinus height and width, and the cervical stages were evaluated on the same radiograph. The Kruskal-Wallis test was applied to compare frontal sinus index values at different cervical stages, and the post hoc Dunnett T3 test was applied to compare frontal sinus index values between adjacent cervical stages for each sex. The Kendall tau-b values were computed to assess the correlation between the cervical stages and the sinus index. A P value of ≤0.05 was considered statistically significant. RESULTS: The height and width of the frontal sinus were significantly larger in the male subjects than in the females. A significant association was found between the frontal sinus height and width and cervical stages (P ≤0.001) in both sexes. However, the changes in the frontal sinus index across the different cervical stages were found to be significant (P ≤0.001) in male subjects only. Similarly, a weak negative correlation was found between the sinus index and the cervical stages in male subjects (tau-b = -0.271; P <0.001), whereas no correlation was found in female subjects (tau-b = -0.006; P <0.928). However, the post hoc analysis showed that the values of the sinus index were comparable between any 2 adjacent cervical stages. CONCLUSIONS: The frontal sinus index cannot be used to identify the prepubertal, pubertal, and postpubertal stages of the adolescent growth spurt. Therefore, it cannot be used as a reliable maturity indicator.

Anterior cranial-base time-related changes: A systematic review.

INTRODUCTION: The anterior cranial base has long been considered a stable reference structure for superimposing radiographs. However, some studies have questioned its stability. Therefore, the purposes of this systematic review were to give an overview of the studies evaluating growth and development of the anterior cranial base, assess their methodologic quality, and evaluate their validity and accuracy. METHODS: Medline, Embase, and Google Scholar were searched without limitations up to June 2013. Additionally, the bibliographies of the finally selected articles were hand searched to identify any relevant publications that were not identified before. The lowest levels of evidence accepted for inclusion were cohort and cross-sectional studies. RESULTS: A total of 11 articles met all inclusion criteria. They were published between 1955 and 2009. The sample sizes of these studies ranged from 28 to 464 subjects. Their methodologic quality ranged from moderate to low. CONCLUSIONS: Sella turcica remodels backward and downward, and nasion moves forward because of the increase in size of the frontal sinus. These events lead to a continuous increase in the length of the cranial base until adulthood. The presphenoid and cribriform plate regions can be considered stable after age 7, making them the best cranial-base superimposition areas.

Association between frontal sinus development and persistent metopic suture.

BACKGROUND: Frontal sinuses are 2 irregular cavities, placed between 2 lamina of frontal bone. Expansion continues during childhood and reaches full size after puberty. Persistent metopic suture is one of the factors that are related to abnormal frontal sinus development. In this study, we want to discuss about the coexistence of persistent metopic suture and abnormal frontal sinus development using radiological techniques. MATERIALS AND METHODS: In this retrospectively planned study, images of 631 patients were examined, 217 (34.4%) of them were men and 414 (65.6%) of them were women. Brain computed tomography and magnetic resonance images were retrieved from the electronic archive for analysis. RESULTS: In this study, frontal sinus development is categorised as right side atrophy, left side atrophy, bilateral atrophy and bilaterally developed sinuses. The presence of metopic suture was accepted as persistent metopic suture. Frontal sinus atrophy was found in 22.7% and persistent metopic sutures were found in 9.7% of overall. CONCLUSIONS: In this study, no significant results were detected that were relatedto the frontal sinus agenesis or dismorphism associated with persistent metopicsuture. We conclude that, although publications propounding metopism thatleads to abnormal frontal sinus development are present in the literature, noreasonable explanation has been mentioned in these articles; and we believe thatthese findings are all incidental.

Three-dimensional computed tomographic analysis of frontal sinus in Asians.

Although there are many reports on the measurement of the paranasal sinuses, few studies examined the development of frontal sinus with three-dimensional computed tomography (CT), especially in children. In this study, we evaluated the normal development of frontal sinus in Asian children, and we also analyzed the height, length, and width of the frontal sinus in Korean adults with three-dimensional CT imaging. We retrospectively reviewed three-dimensional facial bone CT of a total of 352 patients younger than 23 years. The occurrence of the frontal sinus was evaluated by their age. The maximal length, height, and width were measured with a computer device. The volume of the frontal sinus was also evaluated. In those older than 4 years, the pneumatization of frontal sinus was detected. Frontal sinus developed continuously and was observed in almost every child older than 17 years. The length, height, width, and volume of the frontal sinus continuously increased until the age of 20. The maximal growth of the frontal sinus was observed at puberty. The width and volume of the frontal sinus showed a high correlation coefficient (r=0.8) relative to the height or length. In adults, the mean height, width, depth, and volume of the frontal sinus were 27.2±7.0 mm, 52.5±17.1 mm, 22.0±6.3 mm, 8.39±3.78 cm, respectively. The results of this study may be helpful in understanding the normal development of frontal sinuses in children. It could be also helpful for further research and surgical approaches for frontal sinuses.

Frontal sinus: is it a predictor for vertical malocclusions?

The aim of the present study was to evaluate 3D frontal sinus morphology in consideration with different vertical facial developments. The study was conducted with the pre-treatment CBCT images of 87 patients, who were divided into 3 groups according to the sum of the posterior angle. The frontal sinus measurements were performed on the axial, sagittal, and coronal sections of the CBCT images. Craniofacial measurements were performed on the lateral cephalograms, obtained from the CBCT scans. Normal distribution of the data was confirmed by the Kolmogorov-Smirnov test. ANOVA, followed by post hoc Duncan tests, was used to compare the differences among the three groups. The relationships between sinus dimensions and craniofacial parameters were assessed by the Pearson's correlation coefficient (P < 0.05). The maximum anterior-posterior dimension of the frontal sinuses (0.017), the width of the right (0.020) and left (0.041) frontal sinuses, and the anterior-posterior dimension of the left (0.038) frontal sinus were significantly smaller in the hyperdivergent group compared to hypodivergent group. There was no significant difference between groups in terms of the height of the frontal sinuses. Significant correlation was noted between the maximum anterior-posterior dimension of the frontal sinus and SN-PP, N-Me, N-ANS, SN-GoGn, Post. sum, and Jarabak's ratio. No significant correlation between the height of the frontal sinuses and the craniofacial measurements was found. Individuals with vertical growth pattern presented decreased anterior-posterior dimension of the frontal sinuses, revealing significant correlations with vertical craniofacial parameters.

Morphometric Analysis of the Fronto-maxillary Sinuses in Adult Patients with Traumatic Septal Deviations.

OBJECTIVE: The aim of the current study was to investigate a change in the volume of the frontal and maxillary sinuses in patients with nasal septum deviations due to physical trauma. MATERIALS AND METHODS: Paranasal sinus computed tomography data of 100 patients admitted to Kirikkale University medical faculty hospital between November 2013 and June 2014 were retrospectively analyzed. The side of the nasal septal deviation, the deviation angle, the severity of the deviation, and bilateral frontal and maxillary sinus volumes were calculated using a computer program. The relationship between sinus volumes and deviated septum characteristics was investigated. RESULTS: The maxillary sinus volumes did not differ between the two genders. However, the female patients had significantly decreased frontal sinus volumes when compared with the male patients (p < 0.05). A right-sided septal deviation was found to be associated with a significantly decreased maxillary sinus volume (p < 0.001), and the severity of the deviation was a significant determinant of the maxillary sinus volume (p < 0.001). The age of the patient at the time of the septal trauma was significantly associated with their maxillary sinus volumes. Patients who had experienced this trauma after 12 years of age had significantly increased maxillary sinus volumes when compared with those who experienced the trauma before the age of 12. CONCLUSION: A distorted septal anatomy was found to be a significant parameter for developing paranasal sinuses. Right-sided and severe traumatic deviations with an onset before the age of 12 were significantly associated with a decreased maxillary sinus volume.

Frontal Sinus Development and Juvenile Age Estimation.

Assessment of development is an important component of age estimation in juveniles. One area that has not been fully investigated as a possible aging method is the development of the frontal sinus. The frontal sinuses form when the ectocranial table of the frontal bone separates from the endocranial table forming an air pocket in the bone. The endocranial table ceases growth with the brain, while the ectocranial table is displaced anteriorly as the facial bones continue growth. In order to examine growth and the utility of the frontal sinuses for age estimation, 392 radiographs were examined (♀=159 and ♂=233) from the Juvenile Radiograph Database at North Carolina State University and the Patricia Database from Mercyhurst University. The sample included individuals who ranged in age from 0 to 18 years. Anterior view (or AP) radiographs were examined and were grouped based upon the presence or absence of the frontal sinus. Individuals were grouped into four age categories. A one-way ANOVA was performed to test whether developmental phase was related to age. Results from the ANOVA show that developmental phase is significantly related to age (P <.0001). An ordinal logistic regression was conducted to examine whether developmental phase could be used to predict age. The results of the logistic regression suggest that developmental phase is an accurate indicator of age (P <.0001, df = 1, Chi-Squared = 537.2428); however, the age ranges can be quite wide and should be utilized alongside other established methods of age estimation. Anat Rec, 300:1609-1617, 2017. © 2017 Wiley Periodicals, Inc.

Ontogeny and homology of the paranasal sinuses in Platyrrhini (Mammalia: Primates).

The identity and taxonomic distribution of paranasal sinuses among living platyrrhines has remained a contentious issue (e.g., Cave [1967] Am J Phys Anthropol 26:277-288 vs. Hershkovitz [1977] Chicago: University of Chicago Press) largely because the ontogenetic data required for their detection and identification (e.g., Cave [1967]; Maier [2000] Cambridge, UK: Cambridge University Press, 99-132.) were not attainable without sacrificing valuable juvenile and subadult specimens. Non-invasive computed tomography (CT) scanning of ontogenetic series of skulls for 10 platyrrhine genera demonstrates the presence of maxillary and ethmoid sinuses, as well as homologs of the human sphenoid and frontal sinuses. Differences in the latter two sinuses between platyrrhines and hominoids highlight the need for early developmental data in establishing sinus homology. In particular, the identification of homologous recesses in the cartilaginous nasal capsule, from which sinuses later develop, emerges as the critical step. This developmental approach also reveals that the anterior and posterior ethmoid sinuses are each sets of serial homologs, a point which reconciles previous difficulties in establishing sinus homologies across mammalian orders (e.g., Paulli [1900] Gegenbaurs Morphol Jahrb 28:147-178, 179-251, 483-564).

Morphometric evaluation of the frontal sinus in relation to age.

To investigate the development of the frontal sinus size during life, we studied the planar morphometry in 60 frontal radiographs of patients of different age and gender. A professional software (Bersoft Image 4.02) was used to measure the frontal area of the right and left frontal sinuses on radiographic images. A frontal sinus was already evident in 4-year-old children. Unilateral or bilateral absence of the frontal sinus was seen in 5% of cases. The size of the sinusal area increases up to 19-year-old patients, synchronous with general craniofacial growth. In adults, individual differences in size and shape occurred in relation to environmental factors. In some elderly patients, osseous resorption led to an enlargement of the frontal sinus that might complicate surgical procedures performed in this area.

A consideration of the systemic factors that influence frontal sinus pneumatization.

The authors present the embryology and comparative anatomy of the frontal sinuses pertinent to a discussion of the systemic factors which influence frontal sinus pneumatization. There are at least three important factors involved: 1) craniofacial configuration, 2) thickness of the frontal bone, 3) growth hormones. Various clinical entities which illustrate these points are discussed.

Statistical estimators of frontal sinus cross section ontogeny from very noisy data.

Cross-sectional areas of human frontal sinuses in the occipitofrontal projection are a good surrogate for frontal sinus volumes. This study looks at these areas in a dataset of some 200 children and 100 adults of both sexes. As measured by planimetry of roentgenograms, the areas are extremely variable ("noisy" in a statistical sense). In fact, they appear to be distributed log-normally with quite high variance. The mean of the distribution is evidently a function of age and the variances differ by sex. After logarithmic transformation, the data are adequately fitted by one sigmoid curve for each sex. Our discussion highlights implications of this finding for the biological aspects of frontal sinuses and methodological issues in ontogenetic analysis of data so noisy.

Evaluation of the effect of early mobilization of the supraorbital bar on the frontal sinus and frontal growth.

Consequences of early frontocranial remodeling are controversial. It has been said that secondary operations are more difficult and that the frontal sinus does not develop well, with an adverse effect on forehead aesthetics. Some illustrative cases are presented, among 820 operated craniosynostoses, to demonstrate that (1) an early, well-performed frontal advancement and/or remodeling is followed by satisfactory reossification and permits easy secondary surgery, (2) frontal sinus development, which is always impaired in anterior craniosynostosis, is only moderately diminished by early supraorbital bar remodeling (when the frontal bar is repositioned after remodeling, as with trigonocephaly, the frontal sinus develops in 83 percent of cases, whereas when the advancement is significant, as with brachycephaly, the development of the frontal sinus is observed in only 50 percent of the cases), and (3) forehead aesthetics are not linked closely to the development of the frontal sinus. After a significant advancement, even if the sinus does not develop, the frontal bar projection can remain satisfactory.

Osseointegration in sinus-forming bone.

Osseointegration, using bone-anchored titanium fixtures, is a well-established technique for both intraoral and craniofacial prosthetic rehabilitation. The use of this technique in children can be complicated by craniofacial growth and sinus development. This study evaluates the effects of sinus formation and growth on the fate of osseointegrated titanium fixtures in the growing porcine model. At 3 weeks of age, six Landrace White cross male pigs had a 3.75 x 3.0 mm titanium fixture (Noblepharma) inserted into their right frontal bone where the right frontal sinus would subsequently develop. Preoperative CT scans with three-dimensional reconstructions were used to determine the insertion site. To follow the effects of growth and sinus formation, CT scans with three-dimensional reconstructions and cephalometric radiographs were taken at 1, 3, 6, and 9 weeks postoperatively and at sacrifice. The pigs were sacrificed serially, and direct osteometric measurements were taken to determine skull symmetry. All skulls were sectioned, and osseointegration was determined clinically, radiologically, and histologically with light and scanning electron microscopy. Five of the six fixtures osseointegrated. There were no apparent growth disturbances due to the fixtures. As growth progressed, the osseointegrated fixtures submerged into the frontal bone in a posteroinferior direction to become completely intraosseous 14 weeks after insertion. As the frontal sinus pneumatized, the fixtures remained osseointegrated, but progressive amounts of the fixtures became exposed in the sinus. From this study it would appear that osseointegrated titanium fixtures do not have any effect on calvarial growth and gradually submerge into the growing bone. As sinus development ensues, the fixtures remain integrated but become partially exposed within the sinus.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of early fronto-orbital advancement on frontal sinus development and forehead aesthetics.

The frontal sinuses make an important contribution to normal forehead and glabellar contour. This study was designed to test our clinical impression that early fronto-orbital ("frontal bone") advancement could have an adverse effect on frontal sinus development and consequently on forehead aesthetics. A retrospective study was conducted on 11 patients who had undergone fronto-orbital advancement and also had a long period of follow-up at the Institute of Reconstructive Plastic Surgery at New York University. The longitudinal cephalometric data were compared with unoperated controls. With one exception, no patient who underwent bilateral fronto-orbital advancement developed a frontal sinus, and all such patients had a flattened brow contour when compared with unoperated patients, of whom 82 percent developed at least one frontal sinus. Of the three patients who underwent unilateral fronto-orbital advancement for plagiocephaly (flattened forehead), two developed a frontal sinus but only on the unoperated side and one developed bilateral frontal sinuses. The two patients with unilateral frontal sinus development had a particularly obvious deformity resulting from normal glabellar projection on the unoperated side and a flattened contour on the operated side. Fronto-orbital advancement affects forehead aesthetics and should be performed only in infant patients with moderate to severe deformities. patients with plagiocephaly whose deformity is sufficiently severe to warrant surgery should preferably undergo bilateral fronto-orbital advancement (by the technique described) rather than unilateral advancement in order to avoid the brow asymmetry that results from unilateral frontal sinus development.

Development of the frontal sinus following bilateral fronto-orbital osteotomies.

The presence of frontal sinuses following bilateral fronto-orbital advancement is discussed controversially in the literature. In a retrospective study, 33 patients (18 male and 15 female) were operated on between 1982 and 1993, with at least one year postoperative follow-up and with a minimum age of 6 years at the end of the follow-up period following bilateral fronto-orbital remodelling, were included. The average age at which the procedure was performed was 29 months with a minimum of 3 months and a maximum of 7.8 years. The study presented shows a pneumatization of the frontal sinus in 72.7% of 33 patients following bilateral fronto-orbital advancement. The first radiographic signs of sinus development were detected between the ages of 4 and 11, average 8.3 years. There were no statistically proven correlations between frontal sinus pneumatization and age at operation or the amount of advancement or sex of the patients. Surgical enlargement of the cranium by frontal advancement with adequate stabilization results in an enlargement of the neurocranium, thereby decreasing pressure on the inner frontal cortex and allowing frontal sinus pneumatization to proceed normally. Hence, the development of a frontal sinus may be a reflection of the effectiveness of the surgical therapy.

Association of frontal sinus development with somatic and skeletal maturation in Aboriginal Australians: a longitudinal study.

There have been very few studies of frontal sinus development and its association with other growth parameters in humans. The aim of this study was to investigate the relationship of frontal sinus development with somatic and skeletal maturation in a sample of Aboriginal Australians. The sample comprised 31 individuals, of whom 17 were males and 14 females. For the selected subjects the following records were available: lateral head radiographs, hand-wrist radiographs and stature recordings, generally covering the age range from 7 to 18 years. Descriptive statistics for frontal sinus size, skeletal ossification and body height were calculated at yearly intervals and comparisons made between the sexes. Growth velocities in frontal sinus height, frontal sinus depth and stature were also calculated for both sexes. The frontal sinus was found to display a well-defined adolescent growth spurt, with its peak velocity occurring after the peak velocity in body height. Females were found to attain peak velocity in sinus height earlier, on average, than males but they attained peak velocity in sinus depth at a similar age to males. The sequence of hand-wrist ossification events followed a similar pattern in both sexes, with events in females occurring approximately one year earlier than those in males. These results indicate that an adolescent spurt is present in frontal sinus growth and that the spurt tends to occur after statural velocity has peaked. Hand-wrist ossification events also tend to have a close relationship to peak statural and frontal sinus velocity and these relationships may be useful in clinical situations for predictive purposes.

The possible effects of altitude and climate on the development of the frontal sinus in adults / Los posibles efectos de la altitud y el clima sobre el desarrollo del seno frontal en adultos

Climatic and altitude features of living region may affect human body. Many changes in several tissues and organs and several health problems due to climatic and altitude effects were defined in the literature. However, there were limited number of studies which evaluated correlation between development of frontal sinus and climatic/altitude effect. In this study, widths, heights, AP lengths and volumes of frontal sinus were compared by Paranasal CT scans in populations living in Van which has colder climate and higher altitude and Manisa which has milder climate and lower altitude. It was found that widths, antero-posterior lengths and volumes of frontal sinus were higher in populations living in colder climate and higher altitude according to populations living in milder climate and lower altitude. Heights of frontal sinuses were on the contrary of this. These results were found appropriate to increasing of cephalic index in cold climate according to Allen's Rule. We suggest that larger population study should be made with peoples having the same or similar race and genetic structure in different climate and altitude regions and the proportional comparison of frontal sinus measurements with cephalic index should be considered in future studies.

Las características climáticas y de altitud de una región pueden afectar al cuerpo humano. En la literatura se han identificado muchos cambios en varios tejidos y órganos, como así también numerosos problemas de salud debido a los efectos climáticos y de altitud. Sin embargo, existe un número limitado de estudios que han evaluado la correlación entre el desarrollo del seno frontal y el efecto climático / altitud. En este estudio, los anchos, alturas, longitudes antero-posteriores y volúmenes de seno frontal se compararon mediante tomografía computarizada paranasal en poblaciones que viven en Van, que tiene un clima más frío y mayor altitud, y Manisa, que tiene un clima más suave y menor altitud. Se encontró que los anchos, las longitudes antero-posteriores y los volúmenes de los senos frontales eran mayores en poblaciones que vivían en un clima más frío y de mayor altitud respecto a poblaciones que vivían en clima más suave y con menor altitud. En relación a la altura de los senos frontales, se dio la situación contraria a lo anterior. Estos resultados se encontraron adecuados con el aumento del índice cefálico en la región de clima frío, de acuerdo con la Regla de Allen. Sugerimos que se realice un estudio poblacional más amplio con poblaciones de raza y estructura genética iguales o similares en diferentes regiones climáticas y de altitud. La comparación proporcional de las mediciones de los senos frontales con índice cefálico debería considerarse en futuros estudios.