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Difference between the average nonhuman and the average human atlas shape (second and third columns, respectively). The first and the last columns are extrapolations of this difference by a factor of two in either direction. Top row: cranial views with the ventral part at the top. Bottom row: dorsal views with the cranial surface at the top.
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The cervical vertebral column bears or balances the weight of the head supported by the nuchal muscles that partly originate from the cervical vertebrae. The position of the head relative to the vertebral column, and consequently locomotion and posture behavior, could thus be associated with the form of the cervical vertebrae. In spite of this assu...
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Context 1
... locomotion patterns: brachiation, vertical climbing, bipedalism, and quadrupedalism. The values of these four variables for the nine species used in our study are drawn from Gebo (1996), who sum- marized data reported by several other authors (Fleagle, 1976, 1980; Mendel, 1976; Susman, 1984; Tuttle and Watts, 1985; Cant, 1986, 1987, 1988; Mittermeier, 1978; Hunt, 1991; Gebo, 1992; Doran, 1993). Some of these authors provide locomotion fre- quencies for traveling and feeding separately, while others supply only totals. The separate locomotor assess- ments were averaged together for a total locomotion profile (Table 1) as suggested by Gebo (1989). Instead of relating shape to the four locomotion variables separately or to an arbitrary combination of them, we use a two-block partial least-squares (PLS) analysis (Bookstein et al., 1990, 2003; Rohlf and Corti, 2000) between the shape coordinates and all four of these locomotion variables. When PLS is applied to Procrustes coordinates, this procedure is often called singular warp analysis. PLS describes the multivariate relationship between locomotion and atlas shape in terms of a pair of latent variables (one for shape and one for locomotion) that together have the highest possible covariance or predictive power. The weightings for these two linear combinations are contained in the two re- spective singular vectors, and the corresponding singular value is the covariance between the two variables so defined. The actual values of the new variables are called latent variable scores (nonshape) or singular warp scores (shape). The word “singu- lar” comes from an ancient algebraic maneuver (see the references cited above). There further exists a second pair of variables that is (geometrically) or- thogonal to the first pair, such that the corresponding scores, the second pair of singular warp scores, exhibit the highest covariance of any vectors so defined (which covariance equals the second singular value). Subsequent pairs of variables are defined analo- gously. For two blocks of variables (the shape variables and the locomotion variables), the calculation of the singular vectors is based on a singular value decomposition of the cross- block covariance matrix containing all covariances among the two blocks. The maximum number of vectors that can be extracted is the smallest number of variables in either block (in our case, four). The singular warp scores can be plotted against each other in the spirit of a principal component analysis, and the singular vectors containing the weightings of the Procrustes coor- dinates can be visualized as shape deformations. Such visualizations are typically conveyed via thin-plate spline deformation grids or by landmark displacement vectors. For the complex three-dimensional structure of an atlas, we used another visualization technique based on surface representations. The configuration of landmarks was triangulated by hand, enabling visualizations as exemplified in Figure 1. To visualize actual shape changes, we show several of these surfaces as they deform along a specific vector in shape space. All analyses and visualizations in this study were performed with Mathematica 5.0. PLS extracts linear combinations of the four locomotion variables that explain most of the net covariance with atlas shape. The corresponding scores for the shape variables are the scores along those shape changes that covary most with locomotion; it is natural to interpret these as “most responsive” in a functional or developmental sense. In order to test whether a nonhuman model of functional atlas morphology can explain human morphology, we used only the eight nonhuman primate species to calculate the singular vectors. The scores along these vectors were then computed for all species, including humans, to assess whether the human atlas shape is similar to, or is an extrapolation of, the more erect primate taxa along these dimensions. As several previous studies on atlas morphology focused on the shape of the superior articular facets, specifically their convexity, we measure the angle in space between the two trian- gles of landmarks covering the facets (see the gray lines in Fig. 1). We average the angles for the left and right facets on each atlas and subsequently average those for each species. Figure 2 presents the results of the principal component (PC) analysis of the Procrustes shape coordinates (relative warps). The first PC explains approximately 16% of total shape variation and the second 13%. Apparently, the species form distinct clusters that (except for Pongo and Gorilla ) only marginally overlap in the first two PCs. Figure 3 specifically addresses the differences between Gorilla and Pongo by restricting the PCA to those two species. The two scatters clearly differ along the horizontal axis. Whereas the surface representations along the two axes in Figure 2 illustrate the shape changes that correspond to the first two PCs, Figure 4 is a visualization of the differences between the human and the average nonhuman atlas morphology. Com- pared to the average nonhuman primate, the atlas of Homo sapiens is characterized by a more ventrally inclined processus transversus, a less rounded facies articularis superior, a more robust arcus posterior, and a relatively larger foramen transversarium and thus a differently shaped processus transversus. To quantify the average shape differences among the nine species, the average configuration of the Procrustes coordinates was computed for each species and the 36 pairwise Procrustes distances (for shape only) computed among these means. Table 3 lists the Procrustes distances among the species together with the species’ average centroid size. Confirming the PCA of Figure 2, Gorilla and Pongo have the lowest Procrustes distance and are thus most similar in this metric. Homo is most similar to Pan and generally more similar to the great apes than to the other primates. A l- ouatta generally exhibits the largest distances to all other species, including Homo . Gorilla and Homo have the largest atlas vertebrae and Alouatta the smallest. For all 36 Procrustes distances, we carried out a permutation test (10,000 permutations) to assess the significance of the group differences. Except for the pair Alouatta/Ateles , all other 35 tests resulted in a P value less than 0.0004, so that even after a Bonferroni correction the differences remain significant at P ϭ 0.014 or better. The shape distance between Alouatta and Ateles is significant separately at P ϳ 0.007, in spite of the small samples of both. In addition to these general shape comparisons, we specifically compared the convexity of the superior articular facets by the angle between the two triangles spanned by the landmarks 7, 8, 9, 10 (Fig. 1, Table 2). The last column in Table 1 presents averages of them by species. Humans possess the flattest facets, followed by the apes, while in Papio and Ateles the facet is most concave. The average angle in humans differs significantly from each of the others ( P Ͻ 0.002 by permutation test, with 5,000 permutations each). To explore the influence of evolutionary and static allometry on atlas shape, we performed multivariate regressions of the Procrustes shape coordinates on centroid size of the atlas vertebra (Fig. 5). The upper part of Figure 5 is a visualization of evolutionary allometry, i.e., the regression pooling all nine species (Cheverud, 1982; Klingenberg, 1998). On the left side are shown cranial and dorsal views of the atlas shape predicted at two standard deviations less than average size. Similarly, the shapes at the right correspond to a larger vertebra. Apparently, the whole atlas, particu- larly the arcus posterior and its tuber- culum, becomes more robust (that is, thicker) when size increases. A permutation test for the linear dependence of shape on size rejects the null hypothesis of no association at P Ͻ 0.001; explained shape variance, in units of squared Procrustes distance, is 13.9%. The two lower parts of Figure 5 visualize static allometry, the (adult) dependence of shape on size within single species. As the eight nonhuman allometries are quite similar in their main features, we contrasted the allometric trend within humans to a pooled estimate of nonhuman allometry. The allometry within Homo seams very distinct from the pooled nonhuman estimate. In nonhuman primates, the atlas becomes more robust with increasing size, especially the arcus anterior and the arcus posterior, and the processus transversus becomes longer and more cranially oriented. In humans, however, robusticity of the atlas is decreasing with increasing size, while changes of the lateral extension and angulation of the processus transversus are comparable to the nonhuman allometry. For most specimens, we also measured the femur head diameter, which is often regarded as a reliable estimate of body size (Ruff, 1988). We therefore additionally performed all calculations of allometry with femur head diameter instead of centroid size. Also, we calculated evolutionary allometry with species-specific estimates of average body weight from Smith and Jungers (1997). All these results (available on request) were vir- tually identical to the ones using centroid size and are thus not shown here. To assess the influence of locomotion on atlas shape, we performed a PLS analysis of the Procrustes shape coordinates against the four locomotion variables (brachiation, vertical climbing, bipedalism, and quadrupedalism) in the eight nonhuman primate species. The singular values (the covariances between the four extracted pairs or latent variables) are 1.534, 0.335, 0.098, and 0.047. The first singular warp (the first di- mension of the PLS analysis) thus explains 76.2% of the total squared covariance between the shape coordinates and the locomotion variables. The first two singular warps span 92.8% of the total squared covariance ...
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... two scatters clearly differ along the horizontal axis. Whereas the surface representations along the two axes in Figure 2 illustrate the shape changes that correspond to the first two PCs, Figure 4 is a visualization of the differences between the human and the average nonhuman atlas morphology. Compared to the average nonhuman primate, the atlas of Homo sapiens is characterized by a more ventrally inclined processus transversus, a less rounded facies articularis superior, a more robust arcus posterior, and a relatively larger foramen transversarium and thus a differently shaped processus transversus. ...
Citations
... The grey highlighted areas are significant R 2 values from the regression. in gait across the phylogeny. Other studies have shown similar findings in the vertebral columns of both small-and large-sized mammals (e.g., Álvarez et al., 2013, Da Silva Netto & Tavares, 2021, Jones, 2016a; but see Granatosky et al., 2014, Kort & Polly, 2023, Manfreda et al., 2006, Vander Linden et al., 2019. The pelves of mammalian carnivorans were also found to have no correlation with locomotion when phylogeny was taken into account (Lewton et al., 2020). ...
... and procD.pgls. This approach follows other similar studies (e.g.,Álvarez et al., 2013;Da Silva Netto & Tavares, 2021;Jones, 2016a;Manfreda et al., 2006) to provide usable comparison.The degree of morphological variation of each vertebra was determined from how much their shape dispersed in the shape space, which was measured using the Procrustes variance of each vertebra, calculated using geomorph::morpho.disparity. We calculated phylogenetic signal of each vertebra using the Blomberg's K statistic for multivariate data (K mult ;Adams, 2014;Blomberg et al., 2003) geomorph::physignal, to test whether or not species with closer phylogenetic relationship tend to have more similar vertebral shape. ...
During mammalian terrestrial locomotion, body flexibility facilitated by the vertebral column is expected to be correlated with observed modes of locomotion, known as gait (e.g., sprawl, trot, hop, bound, gallop). In small‐ to medium‐sized mammals (average weight up to 5 kg), the relationship between locomotive mode and vertebral morphology is largely unexplored. Here we studied the vertebral column from 46 small‐ to medium‐sized mammals. Nine vertebrae across cervical, thoracic, and lumbar regions were chosen to represent the whole vertebral column. Vertebra shape was analysed using three‐dimensional geometric morphometrics with the phylogenetic comparative method. We also applied the multi‐block method, which can consider all vertebrae as a single structure for analysis. We calculated morphological disparity, phylogenetic signal, and evaluated the effects of allometry and gait on vertebral shape. We also investigated the pattern of integration in the column. We found the cervical vertebrae show the highest degree of morphological disparity, and the first thoracic vertebra shows the highest phylogenetic signal. A significant effect of gait type on vertebrae shape was found, with the lumbar vertebrae having the strongest correlation; but this effect was not significant after taking phylogeny into account. On the other hand, allometry has a significant effect on all vertebrae regardless of the contribution from phylogeny. The regions showed differing degrees of integration, with cervical vertebrae most strongly correlated. With these results, we have revealed novel information that cannot be captured from study of a single vertebra alone: although the lumbar vertebrae are the most correlated with gait, the cervical vertebrae are more morphologically diverse and drive the diversity among species when considering whole column shape.
... The concept of integration refers to the degree of interaction between one or more anatomical structures (Olson & Miller, 1999). Covariation between specific regions of the vertebral column has been studied by focusing on the link between posture and locomotion (Manfreda et al., 2006; as well as the relationship with the cranium (Nalley & Grider-Potter, 2015). ...
The craniocervical junction (CCJ) forms the bridge between the skull and the spine, a highly mobile group of joints that allows the mobility of the head in every direction. The CCJ plays a major role in protecting the inferior brainstem (bulb) and spinal cord, therefore also requiring some stability. Children are subjected to multiple constitutive or acquired diseases involving the CCJ: primary bone diseases such as in FGFR ‐related craniosynostoses or acquired conditions such as congenital torticollis, cervical spine luxation, and neurological disorders. To design efficient treatment plans, it is crucial to understand the relationship between abnormalities of the craniofacial region and abnormalities of the CCJ. This can be approached by the study of control and abnormal growth patterns. Here we report a model of normal skull base growth by compiling a collection of geometric models in control children. Focused analyses highlighted specific developmental patterns for each CCJ bone, emphasizing rapid growth during infancy, followed by varying rates of growth and maturation during childhood and adolescence until reaching stability by 18 years of age. The focus was on the closure patterns of synchondroses and sutures in the occipital bone, revealing distinct closure trajectories for the anterior intra‐occipital synchondroses and the occipitomastoid suture. The findings, although based on a limited dataset, showcased specific age‐related changes in width and closure percentages, providing valuable insights into growth dynamics within the first 2 years of life. Integration analyses revealed intricate relationships between skull and neck structures, emphasizing coordinated growth at different stages. Specific bone covariation patterns, as found between the first and second cervical vertebrae (C1 and C2), indicated synchronized morphological changes. Our results provide initial data for designing inclusive CCJ geometric models to predict normal and abnormal growth dynamics.
... Classically, it has been hypothesized that there is a relationship between cervical spine kinematics and vertebrae morphology in both modern humans (Nowitzke et al., 1994;Cattrysse et al., 2011;Hallgren et al., 2011;Siccardi et al., 2020) and non-human primates (Demes, 1985;Strait and Ross, 1999;Bogduk and Mercer, 2000;Mercer and Bogduk, 2001;Gommery, 2006). Indeed, more recent works tried to demonstrate the existence of a relationship between vertebral morphology and locomotor behavior and neck posture within the order Primates (Manfreda et al., 2006;Parks, 2012;Grider-Potter and Hallgren, 2013;Nalley, 2013;Nalley andGrider-Potter, 2015, 2017;Meyer et al., 2018). However, the possible relationship between neck ranges of motion (ROM) and cervical vertebrae morphology has not been directly studied until recently Grider-Potter et al., 2020). ...
... Much of this research has focused on the morphology of the thoracolumbar region because of its relevance for understanding the evolution of bipedal locomotion in hominins. The cervical region has attracted less attention, but interest in the comparative anatomy and the functional consequences of variation in this part of the vertebral column has increased in recent years (Arlegi et al., 2017(Arlegi et al., , 2018(Arlegi et al., , 2022Manfreda et al., 2006;Meyer, 2015;Meyer et al., 2018;Nalley & Grider-Potter, 2015Nalley et al., 2019a;Vander Linden et al., 2019;Villamil, 2018). Researchers have expanded phylogenetic sampling, incorporated new methodologies, explored patterns of developmental integration, and examined cervical variation in the context of more refined, quantified measures of head and neck postures and locomotor behaviors. ...
... Features of the first (atlas, C1) and second (axis, C2) cervical vertebrae have been the most widely examined across extant primates. Manfreda et al. (2006) explored the relationship between locomotor pattern and the overall bony morphology of the C1 in nine primate taxa, including five hominoid species. They found that primates differ in atlas shape along a locomotor gradient, ranging from terrestrial quadrupedalism to arboreal orthogrady. ...
Objectives: 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.
Materials and Methods: Linear and angular measurements were taken from 530 cer-vical vertebrae representing 146 individual humans, chimpanzees, gorillas, and orang-utans. Specimens were divided into three age-categories based on dental eruption: juvenile, adolescent, and adult. Inter-and intraspecific comparisons were evaluated using resampling methods.
Results: 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.
Discussion: 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.
... Few studies have described discrete traits in the vertebrae of infants, although these scientific publications have mostly been performed on imaging techniques or autopsies of aborted fetuses with craniocaudal shift and malformed organogenesis (Bates and Nale, 2005;Bots et al., 2011;Castori et al., 2016;Chaturvedi et al., 2018;Schut et al., 2016;Ten Broek et al., 2012). In addition, some authors have focused on the prevalence of discrete traits in the vertebrae of adults, mainly in the cervical column (Gonzales et al., 2017;Karapetian, 2017;Manfreda et al., 2006;Miller et al., 2020;Rios et al., 2014;Sanchis-Gimeno et al., 2018c, 2018b. However, studies describing the expression of anatomical variations in the vertebrae of children are scarce (Billmann and le Minor, 2009;Geist et al., 2014). ...
Pre- and postnatal development and variability in discrete vertebral traits have been poorly described in embryonic studies. Numerous authors have reported that these variations are observable only from adolescence; scientific publications on the vertebrae of fetuses and infants are scarce. Thus, the aims of this study were to (1) describe the ontogeny and variability of anatomical variations in the vertebral column of a Spanish infant population and (2) analyze the frequency and relationship between sex, age, and intertrait variables. A total of 4728 vertebrae from 197 skeletons were studied. The age at death ranged from 22 intrauterine weeks to 8 years. Twenty morphological traits related to vertebral column development were analyzed. A descriptive statistical analysis was performed, and the chi-square test was used to measure the relationship between sex, age, and intertrait variables. We observed that 88.32% of skeletons expressed discrete traits along the spine. In fetuses, the double transverse foramen and unclosed transverse process of the axis were the most prevalent traits. In infants older than one year, the appearance of the L5 cleft neural arch, unclosed transverse process of the atlas, and craniocaudal shifts were frequent. A significant result was found between sex and the unclosed transverse process in the axis. The intertrait relationship was significant for all traits that shared the same embryonic structure. Morphological variations became visible following the appearance of ossification centers during the pre- and postnatal periods, and their etiology was associated with embryonic development.
... The literature regarding the cervical region in primates was, until recently, relatively scarce compared with the other spinal regions (e.g., Schultz, 1942Schultz, , 1961Slijper, 1946;Francis, 1955a, b;Toerien, 1957Toerien, , 1961Jenkins, 1969). More recently, the interest in this region has increased, in particular with studies analyzing the morphofunctional interactions with posture and locomotion (Manfreda et al., 2006;Mitteroecker et al., 2007;Been et al., 2014;Nalley and Grider-Potter, 2017;Arlegi et al., 2017Arlegi et al., , 2018Meyer et al., 2018) and the relationship with the cranium Grider-Potter, 2015, 2019;Villamil, 2018). These (and other) studies have used several perspectives to evaluate this functional relationship not only in primates but also in other mammal groups: for example, approaches based on the biomechanical analysis of the cranium (Demes, 1985); kinematic analyses of this complex in the wild and in captivity (Bramble, 1989;Strait and Ross, 1999;Dunbar and Badam, 2000;Cromwell et al., 2001;Choi et al., 2003;Dunbar et al., 2008;Zubair et al., 2019); analyses from radiographs, photographs, electronic sensors, and dissections (Vidal et al., 1986;Graf et al., 1995a, b;Benoit et al., 2020;Jorissen et al., 2020); approaches based on the morphological correlation and integration among traits (Nalley and Grider-Potter 2015;Villamil, 2018); and musculoskeletal analyses to define modules in the craniocervical complex (Diogo et al., 2008(Diogo et al., , 2017Diogo and Wood, 2011;Esteve-Altava et al., 2015;Arnold et al., 2017a;Powell et al., 2018;Boyle et al., 2020). ...
... This could reflex the different muscular (e.g., Dean, 1985a, b) and biomechanical characteristics of the head-neck movement system between these groups, as humans maintain the atlas and the lower cervical vertebrae in a midposition between extreme flexion and extreme extension (Graf et al., 1995b), resulting in a more self-stabilizing resting posture (Schultz, 1942;Adams andMoore, 1975, Dean, 1985a, b;Lieberman, 2011). This might suggest that cervical vertebral morphology is influenced by the biomechanical requirements of head movement and maintenance of the visual field, especially during locomotion, when the advantage of cervical lordosis in pronograde species is minimized owing to the reorientation of the neck (Graf et al., 1995b;Manfreda et al., 2006;Nalley and Grider-Potter, 2015;Arlegi et al., 2017); however, more specific analyses are necessary to test this observation. These results support our hypothesis that differences in postural and locomotor behaviors among groups could be reflected in their pattern of craniocervical correlation. ...
... humans, as a different allometric pattern in the cervical spine compared with other mammals has also been observed in kangaroos: an upright posture and bipedal-saltatorial locomotion taxon (Arnold et al., 2017b). In addition, a positive allometric trend was observed in the atlas and axis of primates (Manfreda et al., 2006;Nalley and Grider-Potter, 2017). Manfreda et al. (2006) observed a significant link between atlas shape and body mass and also that the allometric trend was distinct between the nonhuman primates and H. sapiens in morphological traits related to locomotion patterns. ...
The analysis of patterns of integration is crucial for the reconstruction and understanding of how morphological changes occur in a taxonomic group throughout evolution. These patterns are relatively constant; however, both patterns and the magnitudes of integration may vary across species. These differences may indicate morphological diversification, in some cases related to functional adaptations to the biomechanics of organisms. In this study, we analyze patterns of integration between two functional and developmental structures, the cranium and the cervical spine in hominids, and we quantify the amount of divergence of each anatomical element through phylogeny. We applied these methods to three-dimensional data from 168 adult hominid individuals, summing a total of more than 1000 cervical vertebrae. We found the atlas (C1) and axis (C2) display the lowest covariation with the cranium in hominids (Homo sapiens, Pan troglodytes, Pan paniscus, Gorilla gorilla, Gorilla beringei, Pongo pygmaeus). H. sapiens show a relatively different pattern of craniocervical correlation compared with chimpanzees and gorillas, especially in variables implicated in maintaining the balance of the head. Finally, the atlas and axis show lower magnitude of shape change during evolution than the rest of the cervical vertebrae, especially those located in the middle of the subaxial cervical spine. Overall, results suggest that differences in the pattern of craniocervical correlation between humans and gorillas and chimpanzees could reflect the postural differences between these groups. Also, the stronger craniocervical integration and larger magnitude of shape change during evolution shown by the middle cervical vertebrae suggests that they have been selected to play an active role in maintaining head balance.
... They are structured in three anatomic groups: cervical (C1-C7), thoracic (T1-T12), and lumbar (L1-L5). Each group shares morphological and functional characteristics motivating their anatomic group classification[16][17]. The three groups are illustrated inFigure 1.7.Automatic identification of spinal imaging such as: Computed Tomography (CT) andMagnetic Resonance Imaging (MRI), is crucial in the context of clinical diagnosis and surgical planning. ...
... The three groups are illustrated inFigure 1.7.Automatic identification of spinal imaging such as: Computed Tomography (CT) andMagnetic Resonance Imaging (MRI), is crucial in the context of clinical diagnosis and surgical planning. While some vertebrae, such as the first cervical (C1), have a distinctive shape, other vertebrae, such as neighboring thoracic or lumbar vertebrae, share a visually similar morphological appearance[17]. ...
This research aims to design a garment for people with disabilities in terms of ergonomic and thermal comfort. A new design technique for developing a 3D adaptive global garment model from the human skeleton and the anatomical shape of the person is proposed using 3D scanning technologies.
This overall model is made up of a skeleton model, a garment model connected to each other by the person's body shape, and a thermal regulation model. All the parameters of the overall model make it possible to adapt it to the person's skeleton, then to these body shapes in order to produce a comfortable and efficient garment.
The skeleton model has the power to adjust to the morphology and dimensions of the bones of the spine and thorax, to control the relative positions of these bones in the three characteristic planes: sagittal, coronal and transverse. For the person suffering from scoliosis, it was necessary to accurately detect the 3D path of the spine from the images of an EOS medical scanner. A specific landmark detection model for each vertebra is used to automatically obtain the position of the vertebrae calculated according to the height and the 3D polar angle of each vertebra. The bones of the thorax follow the path of the vertebrae.
Once the skeletal model has been adjusted to the person, it then makes it possible to detect the anthropometric points and the morphological contours of the latter. For this, the model was placed in the body shape of the person resulting from a 3D body scanner. The position of the morphological contours is given by reference marks connected to the skeleton. These strong links with the skeleton are essential so that the garment automatically adapts to the evolution of the patient's pathology over time. At this stage, we were able to connect our graphic model of the garment, integrating the 3D ease of the garment, to these anthropometric and morphological data.
The garment's 3D ease control is essential because it manages the air space between the body and the garment in our thermal regulation model. In the context of thermal comfort, a clothing system consists of the human body, a layer of air space under the clothing, a layer of fabric, and a boundary layer adjacent to the fabric. In addition, for a complete system, one must consider the heat transfer from the skin to the environment, influenced by the thermoregulation of the human body, air gap, tissue and environmental conditions. The thermal regulation model we have proposed can predict the rate of heat transfer and temperature in the garment, skin and air space, which by optimizing the air space allows us to maintain the body in a situation of thermal comfort.
... The anatomy and integration of the cervical vertebrae has been studied principally in relation to locomotion and posture in primates. However, despite clear differences in cervical morphology between humans and nonhuman hominoids, there are few clear links between positional behavior and cervical morphology (Manfreda, Mitteroecker, Booksteinn, & Schaefer, 2006;Nalley & Grider-Potter, 2015, 2017, typical human-like cervical morphology appears late in hominin evolution (Meyer, 2016;Meyer, Williams, Schmid, Churchill, & Berger, 2017), and there appear to be no major selective forces acting on integration between the cervical vertebrae and basicranium among hominoids (Villamil, 2018, but see Arlegi, G omez-Robles, & G omez-Olivencia, 2018). This has led previous researchers to suggest that biomechanical considerations linked to head carriage, facial size, and facial prognathism may be partly responsible cervical morphology (Meyer, 2016;Meyer et al., 2017;Nalley & Grider-Potter, 2015). ...
... The atlas may display unusual patterns of integration within itself in humans, affecting its apparent relationships to other structures (Arlegi, Veschambre-Couture, & G omez-Olivencia, 2020). Previous research focusing on primate atlas morphology has suggested that the atlas in humans is particularly unusual in its morphology and unexpectedly robust (Manfreda et al., 2006). The integration patterns observed here, where relatively thicker atlases are associated with more posteriorly oriented axis dens, are also contrary to these broad evolutionary patterns, as the human axis dens is almost entirely vertically oriented. ...
The nasopharynx is an important anatomical structure involved in respiration. Its bony boundaries, including the basicranium and upper cervical vertebrae, may be subject to selective pressures and constraints related to respiratory function. Here, we investigate phenotypic integration, or covariation, between the face, the basicranial boundaries of the nasopharynx, and the atlas and axis to understand constraints affecting these structures. We collected three‐dimensional coordinate data from a sample of 80 humans and 44 chimpanzees, and used two‐block partial least squares to assess RV (a multivariate generalization of Pearson's r²), rPLS, the covariance ratio, and effect size for integration among structures. We find that integration is significant among some of these structures, and that integration between the basicranial nasopharynx and vertebrae and between the face and vertebrae is likely independent. We also find divergences in the pattern of integration between humans and chimpanzees suggesting greater constraints among the human face and nasopharynx, which we suggest are linked to divergent developmental trajectories in the two taxa. Evolutionary changes in human basicranial anatomy, coupled with human‐like developmental trajectories, may have required that the face grow to compensate any variation in nasopharyngeal structure. However, we were unable to determine whether the nasopharynx or the face is more strongly integrated with the vertebrae, and therefore whether respiration or biomechanical considerations related to positional behavior may be more strongly tied to vertebral evolution. Future work should focus on greater sample sizes, soft tissue structures, and more diverse taxa to further clarify these findings.
... The relationship between head posture and cervical spine is well correlated with respect to the static and functional anatomy of the cervical column. As the cervical column connects the head with the rest of the body along with soft tissues, its function and morphology are influenced by the head posture and function [18]. Forward head posture decreases the craniovertebral angle that causes flexion of the cervical vertebra and increases the load in the extension muscle [15]. ...
Purpose
The prolonged change in the head posture alters the morphological characteristics of cervical vertebrae. The difference in the head posture among subjects with short, normal, and long anterior facial heights might have a significant influence on the morphological characteristics of cervical vertebrae. Thus, the present study was conducted to evaluate the morphometric characteristics of cervical vertebrae in subjects with short, normal, and long faces.
Methods
Based on Frankfort mandibular plane angle (FMA) on lateral cephalograms, 135 subjects were equally divided into three groups, i.e. Group I [Short face], II [Normal face], and III [Long face]. The angular variables like Atlas-dens angle (ADA), Pars interarticularis-dens angle (PDA), Pars interarticularis-vertebrae angle of C3 vertebrae (PVA3), Pars interarticularis-vertebrae angle of C4 vertebrae (PVA4), Lamina-Pars interarticularis angle of C2 vertebrae (LP2), Lamina-Pars interarticularis angle of C3 vertebrae (LP3), and Lamina-Pars interarticularis angle of C4 vertebrae (LP4) in the first four cervical vertebrae were measured, analyzed, and compared. Descriptive statistics, analysis of variance, Bonferroni, and Pearson’s correlation coefficient tests were used. The P value of 0.05 was considered as the level of significance.
Results
All parameters except PDA and PVA3 were comparable among the groups. The PDA was 54.35⁰ ± 1.87⁰, 57.89⁰ ± 1.55⁰, and 60.29⁰ ± 2.83⁰ in Group I, II, and III, respectively; these differences were statistically significant [P < 0.001]. The PVA3 was 42.70⁰ ± 5.64⁰ in Group I, 45.85⁰ ± 3.82⁰ in Group II, and 45.59⁰ ± 5.53⁰ in Group III subjects that were also statistically significant [P < 0.01]. A fairly strong positive correlation was observed between FMA and PDA.
Conclusion
A significant difference was found in the PDA among subjects with short, normal, and long faces. The vertical height of the face had a strong correlation with the morphology of axis vertebra.
... It has been suggested that atlas morphology may be related to several factors. For instance, Manfreda et al. (2006) reported that orthograde species show thinner anterior and posterior arches, a more ventrally and caudally oriented transverse process, and a more inclined and laterally rounded superior articular facets than pronograde species. Nalley and Grider-Potter (2017) showed that skull size and neck posture (e.g., neck inclination angle) were associated with some atlas shape variation, such as the width or craniocaudal length of posterior arches, respectively. ...
The evolution of novel vertebral morphologies observed in humans and other extant hominoids may be related to changes in the magnitudes and/or patterns of covariation among traits. To examine this, we tested magnitudes of integration in the vertebral column of cercopithecoids and hominoids, including humans. Three-dimensional surface scans of 14 vertebral elements from 30 Cercopithecus, 32 Chlorocebus, 39 Macaca, 45 Hylobates, 31 Pan, and 86 Homo specimens were used. A resampling method was used to generate distributions of integration coefficient of variation scores for vertebral elements individually using interlandmark distances. Interspecific comparisons of mean integration coefficient of variation were conducted using Mann-Whitney U tests with Bonferroni adjustment. The results showed that hominoids generally had lower mean integration coefficient of variation than cercopithecoids. In addition, humans showed lower mean integration coefficient of variation than other hominoids in their last thoracic and lumbar vertebrae. Cercopithecoids and Hylobates showed relatively lower mean integration coefficient of variation in cervical vertebrae than in thoracolumbar vertebrae. Pan and Homo showed relatively lower mean integration coefficient of variation in the last thoracic and lumbar vertebrae in the thoracolumbar region, except for the L1 of Pan. The results suggest fewer integration-mediated constraints on the evolution of vertebral morphology in hominoids when compared with cercopithecoids. The weaker magnitudes of integration in lumbar vertebrae in humans when compared with chimpanzees likewise suggest fewer constraints on the evolution of novel lumbar vertebrae morphology in humans.
