Morphology Of Cervical Vertebrae Research Articles

Cephalometric Evaluation of the Relationship Between Cervical Vertebral Morphology and Anomalies and the Cranial Base Angle in Different Facial Types and Skeletal Classes

This study examines the morphology and common anomalies of the cervical vertebrae in different skeletal classes and facial types. This cross-sectional study was conducted on 137 lateral cephalometric images of patients aged 18-55 years. The images were evaluated for fusion and posterior arch deficiency as the two most common anomalies along with cervical vertebral morphology (dense angle, the height of the posterior arch of the atlas, the external anterior posterior diameter of the atlas, and the cranial base angle). Data were categorized into three skeletal classes based on the Wits analysis and the ANB angle and also three facial types based on the SN-MP angle. These calculations were performed in SPSS 22 at the significance level of P<0.05. The height of the posterior arch of the atlas was directly and significantly related to age and increased with it. The mean external anterior posterior diameter of C1 was higher in men and in the hypodivergent group. As for the other factors, including cervical spine anomalies, no significant relationship was observed with age, sex, skeletal classes, facial types, and the cranial base angle. Moreover, the mean morphology of the cervical spine was not significantly associated with skeletal classes. Based on the results, the height of the posterior arch of the atlas was associated with age and increased along with it. Moreover, the mean external anterior posterior diameter of the atlas was greater in men and in hypodivergent individuals.

Comparative ontogeny of functional aspects of human cervical vertebrae.

Differences between adult humans and great apes in cervical vertebral morphology are well documented, but the ontogeny of this variation is still largely unexplored. This study examines patterns of growth in functionally relevant features of C1, C2, C4, and C6 in extant humans and apes to understand the development of their disparate morphologies. Linear and angular measurements were taken from 530 cervical vertebrae representing 146 individual humans, chimpanzees, gorillas, and orangutans. Specimens were divided into three age-categories based on dental eruption: juvenile, adolescent, and adult. Inter- and intraspecific comparisons were evaluated using resampling methods. Of the eighteen variables examined here, seven distinguish humans from apes at the adult stage. Human-ape differences in features related to atlantoaxial joint function tend to be established by the juvenile stage, whereas differences in features related to the nuchal musculature and movement of the subaxial elements do not fully emerge until adolescence or later. The orientation of the odontoid process-often cited as a feature that distinguishes humans from apes-is similar in adult humans and adult chimpanzees, but the developmental patterns are distinct, with human adultlike morphology being achieved much earlier. The biomechanical consequences of the variation observed here is poorly understood. Whether the differences in growth patterns represent functional links to cranial development or postural changes, or both, requires additional investigation. Determining when humanlike ontogenetic patterns evolved in hominins may provide insight into the functional basis driving the morphological divergence between extant humans and apes.

Robotics in Cervical Spine Surgery: Feasibility and Safety of Posterior Screw Placement.

Robot-assisted (RA) techniques have been widely investigated in thoracolumbar spine surgery. However, the application of RA methods on cervical spine surgery is rare due to the complex morphology of cervical vertebrae and catastrophic complications. Thus, the feasibility and safety of RA cervical screw placement remain controversial. This study aims to evaluate the feasibility and safety of RA screw placement on cervical spine surgery. A comprehensive search on PubMed, Cochrane Library, Embase Database, Web of Science, Chinese National Knowledge Databases, and Wanfang Database was performed to select potential eligible studies. Randomized controlled trials (RCTs), comparative cohort studies, and case series reporting the accuracy of cervical screw placement were included. The Cochrane risk of bias criteria and Newcastle-Ottawa Scale criteria were utilized to rate the risk of bias of the included literatures. The primary outcome was the rate of cervical screw placement accuracy with robotic guidance; subgroup analyses based on the screw type and insertion segments were also performed. One RCT, 3 comparative cohort studies, and 3 case series consisting of 160 patients and 719 cervical screws were included in this meta-analysis. The combined outcomes indicated that the rates of optimal and clinically acceptable cervical screw placement accuracy under robotic guidance were 88.0% (95% confidence interval [CI], 84.1%-91.4%; p = 0.073; I2 = 47.941%) and 98.4% (95% CI, 96.8%-99.5%; p = 0.167; I2 = 35.954%). The subgroup analyses showed that the rate of optimal pedicle screw placement accuracy was 88.2% (95% CI, 83.1%-92.6%; p = 0.057; I2 = 53.305%); the rates of optimal screw placement accuracy on C1, C2, and subaxial segments were 96.2% (95% CI, 80.5%-100.0%; p = 0.167; I2 = 44.134X%), 89.7% (95% CI, 80.6%-96.6%; p = 0.370; I2 = 0.000X%), and 82.6% (95% CI, 70.9%-91.9%; p = 0.057; I2 = 65.127X%;), respectively. RA techniques were associated with high rates of optimal and clinically acceptable screw positions. RA cervical screw placement is accurate, safe, and feasible in cervical spine surgery with promising clinical potential.

Correlation between Chronological Age and Cervical Vertebrae Morphology in Adolescents with Class I, II and III Malocclusions

Background: Predicting the best treatment time is an important factor for treating different malocclusions and growth modification treatments. The aim of this study is to compare the mean age of adolescent growth spurt and duration of pubertal growth peak in Class I, Class II and Class III patients according to Baccetti's cervical vertebral analysis. Material & Methods: In this retrospective cross-sectional study, 310 lateral cephalograms (198 girls and 112 boys) aged between 7 and 17 years were examined. The evaluation of skeletal maturation stage was performed by visual analysis of morphological features of the cervical vertebrae (C2, C3, and C4). The skeletal malocclusion was determined by Steiner analysis performed and calibrated independently by two orthodontists. The Kappa coefficient was done to calculate the intra and inter-observer error. Results: This study showed high correlation coefficient between chronological age and skeletal age with class I and II malocclusion, in girls were 0.78 and 0.74 and in boys 0.78 and 0.70 respectively. The results of the study showed a higher correlation coefficient in class III malocclusion, both in girls and boys, (0.83 and 0.82, respectively). In girls the average duration of growth spurt was 1.5 years in class I patients, 0.9 years in class II and 3.5 years in class III patients. In boys the average duration of growth spurt was 1.4 years in class I patients, 1.1 years in class II and 2.9 years in class III patients. Pubertal growth peak occurs earlier in girls with class III malocclusion than in girls with class I and class II malocclusions. Conclusion: The results of this study showed a high correlation coefficient between chronological age and the stages of cervical vertebrae maturation in all three malocclusions. Therefore, it is possible to use CVM to measure skeletal maturity in all three malocclusions. Girls experience adolescent growth spurt 1.3 years earlier than boys on average. Girls with class III malocclusion experience the adolescent growth spurt earlier in comparison to other malocclusions, while class II boys mature later than the others.

Correlating cervical vertebrae morphology and maxillomandibular length among adults with different skeletal relations: A cephalometric study

Correlating cervical vertebrae morphology and maxillomandibular length among adults with different skeletal relations: A cephalometric study

Integration between the bony nasopharynx and the cervical vertebrae in Homo and Pan

Hominin evolution is marked by an increase in the size of the brain and concomitant reorganization of the face and basicranium. As a result, modern human crania are drastically different from those of our closest relatives, including in the nasopharyngeal region, which is necessary for vital life functions such as respiration. The maintenance of nasopharyngeal function serves as an important constraint on the development of surrounding structures, and researchers have documented extensive potential negative consequences. However, little is known about the impact of these functional constraints on the cervical vertebrae, which form the posterior border of the nasopharynx. We tested whether the atlas, axis, face, and the cranial boundaries of the nasopharynx form an integrated module using three-dimensional coordinate data from recent Homo (N =80) and Pan (N =44). We used two-block partial least squares (2B-PLS) to obtain RV values, covariance ratios, and z-scores for each of the following potential modules: nasopharynx-face, nasopharynx-atlas, nasopharynx-axis, face-atlas, face-axis, atlas-axis. P-values were obtained using 999 to 1000 random permutations. Analyses were carried out on MorphoJ and in R using the geomorph package. Our results confirm previous findings that the nasopharynx and face form an integrated module across taxa (Effect size =14.0185, CR =1.0296, P =0.001) but this relationship is weaker within Homo and within Pan. In addition, our results suggest that across taxa the atlas and axis are integrated with the face and nasopharynx (CR = 1.0206-1.058) to a greater extent than they are to each other (CR =0.7797, P =0.001), though again within taxa this effect is less clear. Finally, covariation tends to be stronger between the axis and nasopharynx (Effect size =9.4830), and between the axis and face (Effect size =9.0196), than between the atlas and any structure (Effect size =8.4396-8.7139). However, this difference was not statistically significant and again became less clear within taxa. Together, these results suggest that, across hominids, nasopharyngeal function may be constraining upper cervical vertebral morphology, and especially axis morphology, at least to the same extent as the vertebrae affect each other, if not more. Nonetheless, the importance of these different relationships may vary in different taxa. Future research should focus on clarifying relationships within taxa with larger samples, and expanding the analysis to additional taxa.

Predictability of skeletal sagittal and vertical jaw relationship with its correlation to cervical vertebral morphometry and cervical spine inclination

The cervical vertebra and its relation to maxilla and mandible is of particular interest to orthodontist due to their correlated developmental and anatomical relationship. The aim of the study is to evaluate and correlate the relationship between cervical vertebral morphology and cervical spine inclination with skeletal sagittal jaw relationship and growth pattern for an individual. Cephalogram of 30 subjects was divided in 3 groups based on ANB angle. All the craniofacial and craniocervical landmarks that are required to be analysed were recorded and it was concluded that class III patients had more posterior inclination of dens axis of CV2 but straighter spine inclination on subsequent arches. EVT/VER values indicated more enhanced curvature of vertical column in class II and class III patients. Morphological assessment of CV1SL & CV1HT revealed significantly less measurements in Class III that among class I and II subjects. CV2BL measurement in class II & III was significantly more than class. CV3Sl was significantly more in class III and CV3BL was significantly less in class II.

Femoral neck-shaft angle and bone age in 4- to 24-year-olds based on 1005 EOS three-dimensional reconstructions.

The aim of the study was to assess the correlation between femoral neck-shaft angles (NSAs) and skeletal maturity in EOS reconstructions from a large population of children. Full-body three-dimensional (3D) reconstructions were generated from 1005 children and young adults (4-24 years old; 449 male, 556 female) using the EOS three-dimensional/3D scanner, with images taken during routine clinical practice. The true NSAs were measured and assessed for correlation with individuals' chronological age and bone age, based on cervical vertebral morphology. Statistical analysis was performed using Spearman correlation, independent t-test and multiple linear regression. NSAs of older and younger individuals within each bone age group and chronological age were further assessed by t-test. NSA values fell from mean 131.89° ± 6.07° at 4 years old to 128.85° ± 4.46° at the age of 16, with only minor decreases thereafter. Significantly higher NSAs (3.16° and 4.45°, respectively) were found in those with a bone age advanced or delayed by more two or more stages compared to their peers of the same chronological age (P < 0.001; P < 0.001). Similarly, within most bone age stages, individuals of advanced or delayed chronological age exhibited elevated values (mean difference ranged from 2.9° to 8.9°, P < 0.05). Incorporation of bone age assessment into proximal femoral evaluation allowed identification of 'fast maturing' and 'slow maturing' sub-categories in developing children, with different expected NSAs. The earlier ossification seen in faster-maturing individuals may lead to the NSA becoming fixed in a more immature valgus conformation.

Influences of passive intervertebral range of motion on cervical vertebral form

The cervical spine is the junction between the head and trunk, and it therefore facilitates head mobility and stability. The goal of this study is to test several predictions regarding cervical morphology and intervertebral ranges of motion. Intervertebral ranges of motion for 12 primate species were collected via radiographs or taken from the literature. Morphometric data describing functionally relevant aspects of cervical vertebral morphology were obtained from museum specimens representing these species. We tested for correlations between intervertebral movement and vertebral form using phylogenetic generalized least-squares regression. Results demonstrate limited support for the hypothesis that range of motion (ROM) is influenced by cervical vertebral morphology. Few morphological variables correlate with ROM and no relationship is consistently significant across cervical joints. These results indicate that the relationship between vertebral morphology and joint ranges of motion is, at most, weak, providing little support the use of bony morphology to reconstruct axial mobility in fossil specimens. Future work should investigate the role of soft tissues in vertebral joint stability.

Cervical vertebral maturation assessment on lateral cephalometric radiographs using artificial intelligence: comparison of machine learning classifier models.

This study aimed to develop five different supervised machine learning (ML) classifier models using artificial intelligence (AI) techniques and to compare their performance for cervical vertebral maturation (CVM) analysis. A clinical decision support system (CDSS) was developed for more objective results. A total of 647 digital lateral cephalometric radiographs with visible C2, C3, C4 and C5 vertebrae were chosen. Newly developed software was used for manually labelling the samples, with the integrated CDSS developed by evaluation of 100 radiographs. On each radiograph, 26 points were marked, and the CDSS generated a suggestion according to the points and CVM analysis performed by the human observer. For each sample, 54 features were saved in text format and classified using logistic regression (LR), support vector machine, random forest, artificial neural network (ANN) and decision tree (DT) models. The weighted κ coefficient was used to evaluate the concordance of classification and expert visual evaluation results. Among the CVM stage classifier models, the best result was achieved using the ANN model (κ = 0.926). Among cervical vertebrae morphology classifier models, the best result was achieved using the LR model (κ = 0.968) for the presence of concavity, and the DT model (κ = 0.949) for vertebral body shapes. This study has proposed ML models for CVM assessment on lateral cephalometric radiographs, which can be used for the prediction of cervical vertebrae morphology. Further studies should be done especially of forensic applications of AI models through CVM evaluations.

Correlating the Age Estimated by Nolla's Method and Modified Demirjian Method with Cervical Vertebral Maturation Index: A Cross-Sectional Study

Introduction: Among various methods of dental age (DA) estimation, Demirjian method and Nolla’s method are commonly used. One of the methods of determining cervical vertebral morphology was given by Hassel and Farman. Indian age-specific modified Demirjian method by Acharya has not been utilized in the Hyderabad population, and the age derivation information is sparse. Objectives: To correlate the DA using modified Demirjian’s method and Nolla’s method using orthopantomograph with skeletal maturation by cervical vertebral maturation index (CVMI) method using lateral cephalogram. They were compared and correlated for assessing chronological age (CA) and determining the accuracy. Materials and Methods: Among 200 boys and girls (100 each) between 6 and 21 years, the DA was evaluated using orthopantomogram by Ashith Acharya’s modified Demirjian method and also by Nolla’s method. The skeletal maturation was assessed by CVMI method given by Hassel and Farman using lateral cephalogram. These were compared and correlated with CA. The data derived were statistically analyzed using SPSS software 20.0 version. Results: The maximum underestimation of age was found within the age group of 19–19.9 years using Ashith Acharya’s modified Demirjian method and 18-18.9 years using Nolla’s method with median values of −5.05 and −5.03, respectively. Statistically significant difference was found between CAs and cervical vertebral maturation stages in both genders (P = 0.000). The study showed that girls had a late dental development compared to corresponding cervical maturation. Conclusions: The methods of age estimation were not reliable in predicting the accurate age in the Indian population.

Intraspecific male combat behaviour predicts morphology of cervical vertebrae in ruminant mammals.

Cranial weapons of all shapes and sizes are common throughout the animal kingdom and are frequently accompanied by the evolution of additional traits that enhance the use of those weapons. Bovids (cattle, sheep, goats, antelope) and cervids (deer) within the mammal clade Ruminantia are particularly well known for their distinct and varied cranial appendages in the form of horns and antlers, which are used as weapons in intraspecific combat between males for access to mates. Combat in these species takes many forms, including head-on collisions (ramming); stabbing an opponent's head or body with horn tips (stabbing); rearing and clashing downwards with horns (fencing); or interlocking antlers or horns while vigorously pushing and twisting (wrestling). Some aspects of weapon and skull morphology have been linked to combat behaviours in bovid and cervid species, but the contribution of postcranial structures that support these weapons, such as the neck, has not been explored. To investigate the role of the neck in intraspecific combat, we quantified biomechanically relevant linear variables of the cervical vertebrae (C1-C7) from males and females of 55 ruminant species. We then used phylogenetic generalized least-squares regression to assess differences among species that display primarily ramming, stabbing, fencing and wrestling combat styles. In males, we found that wrestlers have longer vertebral centra and longer neural spines than rammers, stabbers or fencers, while rammers have shorter and wider centra and taller neural spine lever arms. These results suggest a supportive role for the cervical vertebrae in resisting forces generated by male-male combat in ruminant mammals and indicate that evolutionary forces influencing cranial weapons also play a role in shaping the supporting anatomical structures.

Cone beam computed tomography evaluation of the relationship between atlantodental interval and skeletal facial morphology in adolescents

IntroductionIn the pediatric population, computed tomography examination of the upper cervical spine plays an important role in the diagnosis of neurological injuries involving that region. Due to the interconnected nature of the craniofacial structures, a structural change in one is expected to also cause changes in the other structures. ObjectiveThe aim of this study was to evaluate relationships between atlantodental interval, cervical vertebral morphology, and facial structure in healthy adolescents using cone beam computed tomography. MethodsThirty subjects aged 14–20 years (10 males, mean age: 17.2 years; 20 females, mean age: 17.9 years) were included in the study. The anterior, lateral and posterior atlantodental intervals, and vertical and anteroposterior dimensions of the first and second cervical vertebrae were evaluated from cone beam computed tomography images. Facial morphology was evaluated using 7 parameters on lateral cephalometric cone beam computed tomography images and 6 parameters on posteroanterior images. The Mann–Whitney U test and Wilcoxon test were used for statistical analyses. ResultsComparisons between males and females showed that most parameters were larger in males, with significant differences in vertical facial dimensions (anterior lower face height: p = 0.05; anterior upper face height: p = 0.001), (distance between the most internal point of the frontozygomatic suture and midsagittal reference plane; p = 0.01), (the distance between the deepest point of the right alveolar maxillar process and midsagittal reference plane; p = 0.001), and C2 vertebral dimensions. The anterior and lateral atlantodental interval values correlated with maxilla position relative to the mandible angle, and the anterior atlantodental interval correlated with lower anterior facial height (p = 0.05). Dimensional measurements of the C1 and C2 vertebrae were correlated with both anterior facial heights and some posteroanterior parameters. ConclusionSagittal, vertical, and transverse facial dimensions and positions were strongly associated with C1 and C2 vertebral dimensions, and the maxillomandibular relationship may affect atlantodental interval. Therefore, including craniofacial features in assessment of the atlantodental area and vertebral distances in adolescents may be beneficial.

Arcuate foramen: "Anatomical variation shape or adaptation legacy?"

The groove of the vertebral artery on the posterior arch of the atlas (sulcus arteriae vertebralis) may become a complete or partial osseous foramen: the arcuate foramen. The presence of a complete or partial arcuate foramen is a rare anatomical variant described in a minority of patients and it seems to be associated with vertigo, vertebro-basilar insufficiency, posterior circulation strokes, and musculoskeletal pain. As the number and morphology of cervical vertebrae is highly preserved, we questioned about its significance from an evolutionary point of view. We thus investigated through an extensive literature review if the arcuate foramen is a pure anatomical variation shape or if it might represent an adaptation legacy. We observed five atlas of an extinct species, the Late Pleistocene Mammoths (M. primigenius), and we compared them with five atlas of a closely related existent species, the African elephant (L. africana). All the mammoths' atlas had an arcuate foramen through which the vertebral artery passed before turning anteriorly and becoming intradural. This foramen was not present in elephants' atlas, where only a groove was observed, such as in the majority of patients. We would like to raise the hypothesis that this peculiar morphology of mammoths' atlas might have contributed, in association with other factors, to their precocious extinction and that the arcuate foramen might represent a disadvantage in the evolutionary process, with a low prevalence in humans being the result of a natural selection.

Linderochelys rinconensis (Testudines: Pan-Chelidae) from the Upper Cretaceous of northern Patagonia: New insights from shell bone histology, morphology and diagenetic implications

The panchelid turtle Linderochelys rinconensis de la Fuente, Calvo and González Riga, 2007 was described on the basis of several postcranial elements from the Rio Neuquén Subgroup of Loma del Lindero site, near Rincon de los Sauces (Neuquén, Argentina). New preparation of the type material revealed new parts of the animal, including cervical vertebrae, parts of the carapace and a right tibia. The study of the newly recovered material herein improves our knowledge of the macroanatomy of this taxon. The first costal shows an axillary buttress similar to Australasian chelids and the cervical vertebrae morphology suggests a short-necked chelid condition. The re-examination of the type material of Linderochelys and the discovery of new material allowed new studies on microanatomy, osteohistology and diagenesis. Osteohistology suggests some similarities with Patagonian Cretaceous and Palaeocene Yaminuechelys, based on the presence of parallel-fibred bone in the external cortex and a much thinner internal cortex. Paleoecological studies on the proportions of forelimbs and microanatomy point towards aquatic or semi-aquatic habits, closely related to the condition seen in some extant South American chelids, such as Phrynops hilarii, Phrynops geoffroanus, and Mesoclemmys gibba. The fossil-diagenetic processes inferred substitution, fracturing, plastic deformation and permineralization events. Combined analyses through scanning electron microscopy with energy-dispersive X-ray spectrometry and petrographic studies revealed the substitution of hydroxyapatite by francolite. Permineralization stages include infilling of vascular canals, trabeculae and fractures with iron oxides and carbonate minerals during their burial history.

Functional analyses of the primate upper cervical vertebral column

Recent work has highlighted functional correlations between direct measures of head and neck posture and primate cervical bony morphology. Primates with more horizontal necks exhibit middle and lower cervical vertebral features that indicate increased mechanical advantage for deep nuchal musculature and mechanisms for column curvature formation and maintenance. How features of the C1 and C2 reflect quantified measures of posture have yet to be examined. This study incorporates bony morphology from the upper cervical levels from 20 extant primate species in order to investigate further how posture correlates with cervical vertebrae morphology. Results from phylogenetic generalized least-squares analyses indicate that few vertebral features exhibit a significant relationship with posture when accounting for differences in size. When size-adjusted traits were correlated with posture, vertebral variation had a stronger relationship with neck posture than head posture variables. Two C1 traits—relative posterior arch length and superior facet curvature—were correlated with neck posture variables. Relative posterior arch length exhibits a positive relationship with neck posture, while superior articular facet curvature demonstrates a negative relationship, such that as the neck becomes more horizontal, the greater the facet curvature. Four C2 features were also correlated with neck posture: relative pedicle and lamina lengths, relative superior facet orientation, and dens orientation. Relative pedicle and lamina lengths become craniocaudally longer as the neck becomes more horizontal. Relative C2 superior facet orientation and dens orientation exhibit negative correlations with posture, such that as the neck becomes more horizontal, the superior facet becomes more caudally inclined and the dens more dorsally inclined. These results produce a similar functional signal observed in the middle and lower cervical spine. Modeling the cervical vertebrae of more pronograde taxa within a sigmoidal spinal column model is further discussed and may prove useful in refining and testing future hypotheses of primate cervical mechanics.

Three-Dimensional Evaluation of Cervical Vertebral Morphology in Skeletal Class II of Malocclusion in Egyptians

Three-Dimensional Evaluation of Cervical Vertebral Morphology in Skeletal Class II of Malocclusion in Egyptians

An integrated approach to understanding the role of the long neck in plesiosaurs

The evolution and function of the long neck in plesiosaurs, and how the problems associated with stiffness or flexibility were overcome during feeding, or rapid swimming during predator avoidance, are explored, and a new interpretation for the function of the plesiosaur neck is presented. Based on the anatomy of the articular faces of contiguous cervical vertebral centra, neural arches, and cervical ribs, the plesiosaur neck was mainly adapted for ventral bending, with dorsal, lateral and rotational movements all relatively restricted. Predominant ventral bending indicates the neck was adapted for use beneath the body, suggesting feeding in the water column, close to the sea floor, or within soft sediments on the sea floor. A new model is proposed for the plesiosaur bauplan, comprising the head as a filter, straining, sieve feeding or sediment raking apparatus, mounted on a neck which acted as a stiff but ventrally flexible feeding tube, attached to the body which acted as a highly mobile feeding platform. Numerous features of plesiosaurs, including cranial and dental form, cervical vertebral morphology, body shape and limb-based propulsion, conform to this model. Comparative data from modern organisms support this novel explanation for the structure and function of the plesiosaur long neck. This integrative analysis offers an explanation for the evolution of the plesiosaur long neck as a key evolutionary novelty, and why this apparently enigmatic feature remained a prominent feature of plesiosaurs throughout their long evolutionary history.

Influence of skeletal class in the morphology of cervical vertebrae: A study using cone beam computed tomography.

To quantify the prevalence of cervical vertebrae anomalies and to analyze any association between them and skeletal malocclusions or head posture positions in the same study. Two hundred forty patients who were attending the Department of Orthodontics of the University of Valencia for orthodontic treatment were selected and divided into three groups: skeletal Class I (control group, 0° <ANB < 4°), Class II (ANB ≥ 4°), and Class III (ANB ≤ 0°) according to ANB Steiner angle. The morphology of the first five cervical vertebrae was analyzed with cone beam computed tomography to identify any anomalies. Intra- and interobserver error methods were calculated. Dehiscence and fusion of one unit (both 23.3%) and partial cleft (11.7%) were the most frequent anomalies, while occipitalization was the least common (3.3%). Dehiscence anomaly was observed when the control group was compared with Classes II and III and partial cleft anomaly when Class I was compared with Class III. Furthermore, NSBa and ss-N-sm/ANB angles were associated with partial cleft anomaly, while NSL/NL angle and extended head posture were associated with fusion anomaly. Fusion, dehiscence, and partial cleft were the most frequent cervical vertebrae anomalies. Dehiscence and partial cleft were found to present statistically significant differences between Class I and Classes II and III. Cervical vertebrae anomalies and head posture were associated with fusion.

Cervical Vertebral Morphology and Neck Mobility in Gibbons (Hylobates lar) and Humans

The form and function of the primate cervical spine is poorly understood. Specifically, how the bony morphology of the cervical vertebrae facilitates spinal range of motion within primates is not known. Within mammals, primate cervical vertebrae present relatively unique morphologies, such as the uncinate processes. The objective of this study was to investigate the relationship between vertebral morphology and range of motion in the cervical spine of gibbons and humans. Vertebral morphology is variable within the cervical column (i.e. the morphology of C3 is different from that of C7). Range of motion also varies between intervertebral joints. These variations allow us to explore the relationship between form and function intraspecifically. We predict that range in flexion will be greater in vertebrae with taller bodies, extension inhibited by long spinous processes, and the range of lateral flexion will be lesser in vertebrae with longer transverse process length and taller uncinate processes. These hypotheses were tested using humans and gibbons (Hylobates lar).Morphological variables were quantified by digitizing cervical vertebral specimens (n=130) using a Microscribe 3DS and measured using Rhinoceros 3DM. Gibbon range of motion was measured from radiographs of maximum flexion, extension, and lateral flexion movements (n=1) and human range of motion was collected from the literature. Ordinary least squares (OLS) regression was used to test the intraspecific relationships between vertebral morphology and ranges of motion. In both gibbons and humans, regression results indicate a relationship between the range of lateral flexion and the length of the adjacent transverse process (p&lt;0.1) but no relationship between the other variables. It may be that soft tissue influences ranges of flexion and extension more so than bony morphology. It is also possible the intraspecific differences are too minute to show a significant pattern. An interspecific comparison could elucidate a pattern.Support or Funding InformationThis project was supported by the National Science Foundation's East Asia and Pacific Summer Program.