Journal of Anatomy最新文献

{"title":"The secret in their eyes: A review of the recessus orbitalis, a unique structure of flatfishes.","authors":"Paulo Presti, G David Johnson, Aléssio Datovo","doi":"10.1111/joa.70000","DOIUrl":"https://doi.org/10.1111/joa.70000","url":null,"abstract":"<p><p>Flatfishes (Pleuronectiformes) are famous for having one of the most peculiar anatomical transformations in the animal kingdom, the ontogenetic migration of one eye from one side of the head to the other. But the eyes of flatfishes also carry a much lesser known but equally unique modification: an organ called the recessus orbitalis, which is responsible for projecting the eyeball above the level of the head, thus expanding their fields of vision. However, the morphology and distribution of the organ have never been thoroughly investigated. Previous studies reported only part of the recessus orbitalis and mistakenly suggested that it opened into the orbital cavity. We show that the organ forms a fully enclosed system consisting of two interconnected chambers: the facial chamber, which corresponds to the organ previously reported in the literature, and the scleral chamber, which encases the inner portions of the eyeball and is more challenging to detect through manual dissection. The organ is filled with interstitial fluid, and the walls of both chambers-especially the facial one-contain smooth, not skeletal and muscle fibers. These findings combined with field observations allowed us to propose a new functional model for the recessus orbitalis. The organ seems to operate as a dual-pump system, dynamically shifting interstitial fluid between the facial and scleral chambers. Inflation of the facial chamber results in eye retraction, whereas inflation of the scleral chamber causes eye protrusion. The presence of smooth muscle fibers, which can sustain contractions with minimal energy expenditure, supports this inferred mechanism, allowing the eye to remain fully protruded or retracted for extended periods. The recessus orbitalis has never been confirmed in several flatfish families, and the organ was recently considered absent in Psettodidae, the sister group to all other flatfishes. However, we positively identified this organ in all 74 species examined representing all 16 currently recognized flatfish families, including Psettodidae. This indicates that the presence of the recessus orbitalis is an evolutionary novelty (synapomorphy) for the entire Pleuronectiformes.</p>","PeriodicalId":14971,"journal":{"name":"Journal of Anatomy","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-06-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144234189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Data-driven standards for infant skull thickness distributions in computational modeling and analysis.","authors":"Yousef Alsanea, Tagrid M Ruiz-Maldonado, Brittany Coats","doi":"10.1111/joa.14287","DOIUrl":"https://doi.org/10.1111/joa.14287","url":null,"abstract":"<p><p>Child abuse remains a global issue, with infants under 1 year of age facing the highest risk of fatality and recurrence if abuse is not detected. Computational modeling is a powerful tool for predicting injury from real-world trauma, offering a means to validate caretaker-reported histories and prevent further abuse. A key challenge and gap, however, lies in capturing the natural anatomical variability within a population to enhance injury prediction accuracy. This study addresses this gap by quantifying skull thickness distributions in a robust sample (n = 266) and establishing data-driven anatomical standards based on similarities in thickness patterns. The study examined age and head circumference as predictors of skull thickness growth. For infants younger than 2.5 months, head circumference was a more reliable predictor than age. Infants under 12 months old were categorized into four age groups-0-1.5, 1.5-5.9, 5.9-10.2, and 10.2-12 months-using natural thickness distribution breaks and a variance optimization routine. No significant sex differences were found in average skull thickness within each cranial bone (left and right parietal, frontal, and occipital), but there were 53 locations with significant sex differences at various stages of development. Symmetry tests suggested that lateral symmetry may be an appropriate assumption for infants under 12 months. Representative thickness distributions for each age group were selected based on similarity scores. This study is the first to apply data-driven methods to categorize infant skull thickness distributions, generating essential guidelines for age- and sex-based models in predicting injury from head trauma in infants.</p>","PeriodicalId":14971,"journal":{"name":"Journal of Anatomy","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144208554","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Three-dimensional analysis of seminiferous tubules and spermatogenesis in the musk shrew, Suncus murinus.","authors":"Hiroki Nakata, Mahiro Yamaguchi, Takuya Omotehara, Koichiro Ichimura, Shuang-Qin Yi, Shoichi Iseki","doi":"10.1111/joa.14288","DOIUrl":"https://doi.org/10.1111/joa.14288","url":null,"abstract":"<p><p>We reconstructed in three dimensions all seminiferous tubules in the testes of 1- and 8-week-old musk shrews (Suncus murinus), a small experimental mammal belonging to the family Soricidae, order Eulipotyphla that preserves the primitive characteristics of mammalian species. Quantitative analyses revealed that the basic structure of seminiferous tubules at 1 week postpartum remained consistent into adulthood. A single dominant seminiferous tubule with extensive branching accounted for more than 90% of the length of all tubules, a feature distinct from that in mice and rats. Pachytene spermatocytes were observed in the seminiferous epithelia of most tubules at 1 week, which was markedly earlier than in mice and rats. At 8 weeks, a mosaic pattern of active and inactive areas of spermatogenesis was observed through the length of seminiferous tubules, a feature distinct from that in mice and rats. The percentage of active areas was significantly lower in tubule portions near the rete testis. The unique characteristics of seminiferous tubules in the musk shrew will provide a basis for investigating not only the phylogeny of testis functions but also the regulation of spermatogenesis and possibly the pathogenesis of azoospermia.</p>","PeriodicalId":14971,"journal":{"name":"Journal of Anatomy","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144208555","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Continuity of interstitial spaces within and outside the human lung.","authors":"Jeffrey Ordner, Navneet Narula, Luis Chiriboga, Briana Zeck, Mariam Majd, Kapish Gupta, Rebecca Gaglia, Fang Zhou, Andre Moreira, Rami Iman, Jane P Ko, Linda Le, Rebecca G Wells, Neil D Theise","doi":"10.1111/joa.14280","DOIUrl":"https://doi.org/10.1111/joa.14280","url":null,"abstract":"<p><p>There is a body-wide network of interstitial spaces that includes three components: a large-scale fascial network made up of fluid-filled spaces containing collagens and other extracellular matrix components like hyaluronic acid (HA), the peri-vascular/capillary interstitium, and intercellular interstitial spaces. Staining for HA within the colon, skin, and liver has demonstrated spatial continuity of the fascial interstitium across tissue layers and between organs, while continuity of HA staining between perineurial and adventitial sheathes beyond organ boundaries confirmed that they also participate in this body-wide network. We asked whether the pulmonary interstitium comprises a continuous organ-wide network that also connects to the body-wide interstitium via routes along nerves and the vasculature. We studied archival lung lobectomy specimens containing normal tissues inclusive of all lung anatomical units from six females and three males (mean age 53+/- 16.5 years). For comparison, we also studied normal mouse lung. Multiplex immunohistochemical cocktails were used to identify: (1) HA, CD34, and vimentin - highlighting interstitium; (2) HA, CD34, and podoplanin (D2-40) - highlighting relationships between the interstitium, vasculature, and lymphatics. Sizes of extracellular APP were measured. Tissues from nine patients (six females, three males, mean age 53+/- 16.5 years) were studied. HA staining was continuous throughout the five major anatomic compartments of the lung: alveolar walls, subpleural connective tissue, centrilobular peribronchovascular compartment, interlobular septal compartment, and axial peribronchovascular of the hilum, with similar findings in murine lung tissue. Continuity with interstitial spaces of the perineurium and adventitia was confirmed. The distribution of APP corresponded to known routes of lymphatic drainage, superficial and deep. APP within perineurium and perivascular adventitia further demonstrated continuity between intra- and extrapulmonary interstitium. To conclude, all segments of the lung interstitium are connected and are linked along nerves and the vascular tree to a body-wide communication network. These findings have significant implications for understanding lung physiology and pathobiology, suggesting routes of passage for inflammatory cells and mediators, malignant cells, and infectious agents. Interstitial spaces may be important in microbiome signaling within and beyond the lung and may be a component of the lung-brain axis.</p>","PeriodicalId":14971,"journal":{"name":"Journal of Anatomy","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144182466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Morphological features of serosa-associated lymphoid clusters of the rat parietal pleura: Exploring a relatively unexplored system.","authors":"Rosa E Lagerwerf, Claire Mackaaij, Frieke Kuper, Ronald L A W Bleys, Cindy G J Cleypool","doi":"10.1111/joa.14286","DOIUrl":"https://doi.org/10.1111/joa.14286","url":null,"abstract":"<p><p>Serosal membranes contain secondary lymphoid structures that monitor body cavity fluid and can initiate immune responses. While serosa-associated lymphoid clusters (SALCs) of the omental peritoneum (also known as milky spots) are well studied, research on pleural (p)SALCs is limited. This study aimed to examine the distribution, 3D in situ morphology, and cellular composition of SALCs in the parietal pleura in rats. By providing detailed anatomical data, this research may guide future studies on their presence in humans and for potential extrapolation of functional characteristics from rats to humans, if morphological similarities exist. The thorax of fixed Wild type Long Evans female rat cadavers was opened, followed by in toto staining with hematoxylin to improve in situ SALC visibility. Pleural segments, as previously described for rats, were allocated and subsequently stereomicroscopically studied for the presence of pSALCs to gain insight into their topographical distribution and in situ 3D morphological characteristics. To confirm that these structures indeed represent SALCs, tissue sections of each morphological subtype were microscopically studied for the presence of lymphocytes and macrophages, the primary constituents of SALCs. SALCs were observed in decreasing order in the retropericardial pleural folds (RPF), the adipose streak, pulmonary ligaments, and the ventral mediastinal pleura (VMP), whereas no SALCs were observed in pericardial, paravertebral, costal, and diaphragmatic pleura. In situ, pSALCs could be divided into four 3D morphological categories: flat, vascular, adipose, and protruding. Microscopic investigation showed that all pSALC subtypes contained T cells, B cells, and macrophages, confirming the lymphoid nature of these structures. Data provided by this study forms the basis for future morphological comparisons with humans and the potential to extrapolate functional characteristics of pSALCs from previous experimental studies in rats to humans. Our study shows that some SALC containing pleural segments are unique to rats and these interspecies differences should be considered carefully when designing future studies in humans. Furthermore, the phenomenon of distinct 3D SALC morphological subtypes requires further investigation to determine their functional implications, including any relationship between three-dimensional structures and e.g. immune activation.</p>","PeriodicalId":14971,"journal":{"name":"Journal of Anatomy","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144142592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Under the surface: Correlates with maxillary sinus shape.","authors":"Ellen E I Fricano, Joseph Nguyen, Ryan Hallal, Catherine J Llera Martín","doi":"10.1111/joa.14283","DOIUrl":"https://doi.org/10.1111/joa.14283","url":null,"abstract":"<p><p>Despite the central role that the maxillary sinus plays in facial architecture, its shape has never been robustly analyzed in part due to its amorphous morphology and the lack of repeatable landmarks. While previous research has examined correlations between sinus volume and two-dimensional measurements with factors like sex, age, and environmental influences, less is known about finer structural variations, such as trabeculation and surface complexity, in relation to these variables. This study aimed to explore how maxillary sinus size and shape correlate with factors such as age, sex, tobacco, and drug use. The left and right maxillary sinuses of 109 adult individuals were segmented from CT scans. A novel application of spherical harmonic analysis was conducted to quantify maxillary sinus shape. Statistical analyses, including principal component analysis, t-tests, and Mann-Whitney U tests, were employed to assess differences in sinus shape due to sex, age, tobacco use, and drug use. Results showed significant differences in sinus shape due to sex, tobacco, and drug use. The areas of highest variation between groups were at the lateral-most apex and the anterior wall at the superior and inferior corners. Males have larger sinuses, but no other significant differences in sinus size or asymmetry were identified among the groups tested. Previously identified patterns in maxillary volume across age groups were not supported. This study illustrates the areas of highest variability in relation to each variable and has important implications for future studies seeking to understand sinus structure and drainage across groups.</p>","PeriodicalId":14971,"journal":{"name":"Journal of Anatomy","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144142566","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Change in diameters of the small intestine according to embryonic and early fetal growth.","authors":"Nanase Ishida, Toru Kanahashi, Jun Matsubayashi, Hirohiko Imai, Joerg Männer, Shigehito Yamada, Tetsuya Takakuwa","doi":"10.1111/joa.14285","DOIUrl":"https://doi.org/10.1111/joa.14285","url":null,"abstract":"<p><p>No previous studies have examined the diameter of the small intestine successively from the oral to the anal side of the small intestine. Therefore, the objectives of this study were to determine the successive intestinal diameters from the oral to the anal side (proximal to the distal) of the intestine, evaluate changes in diameter associated with growth, examine the effects of positional variation along the intestinal tract, investigate dynamic positional change from the extraembryonic coelom to the abdominal cavity, and assess the impact of complex tertiary intestinal loop formation. To this end, 14 human embryonic and fetal specimens with crown-rump lengths (CRLs) ranging from 25.6 to 69.0 mm were selected for high-resolution magnetic resonance imaging acquisition. The small intestines of the specimens were located in the extraembryonic coelom (herniation phase), transitioning phase, or abdominal cavity (return phase). The small intestine and mesentery were reconstructed in three dimensions, and the resulting morphological changes were observed and analyzed. Successive intestinal diameters from the oral to anal side of the small intestine were determined. Specifically, we observed the following: (1) gradual changes in the diameter of the position from the oral to the anal side in the jejunum-ileum, (2) the difference between the duodenum and jejunum-ileum, and (3) the difference between the superior part of the duodenum derived from the foregut and the remaining parts derived from the midgut. (4) Notably, the dynamic positional change from the extraembryonic coelom to the abdominal cavity, along with the rapid elongation and complex intestinal loop formation-a conspicuous phenomenon in the embryonic and early fetal periods-had little effect on the changes in diameter. This study indicates that increased diameter may serve as a useful indicator of intestinal development and differentiation, independent of tertiary intestinal loop formation and positional changes into and out of the abdominal cavity.</p>","PeriodicalId":14971,"journal":{"name":"Journal of Anatomy","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144142585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Comparative embryology of the squamate pancreas: Structural and 3D studies on the sand lizard (Lacerta agilis) and brown anole (Anolis sagrei).","authors":"Rupik Weronika, Magdalena Kowalska, Paweł Kaczmarek","doi":"10.1111/joa.14284","DOIUrl":"https://doi.org/10.1111/joa.14284","url":null,"abstract":"<p><p>This study investigates the developmental processes of the pancreas in two squamate species: the sand lizard (Lacerta agilis, Laterata) and the brown anole (Anolis sagrei, Iguania). Utilizing histological serial sections, we generated 3D reconstructions of the pancreas and its associated structures. Through a comparative analysis, we identified shared developmental events, including the emergence of specific structures and the initiation of distinct processes, to elucidate patterns of pancreatic differentiation and morphology. The pancreas of the sand lizard originates from three buds, while that of the brown anole originates from only two. In the sand lizard, the adult-like pancreas has an elongated Y-shape, while in the brown anole, the pancreas resembles the letter T on its side. Despite the differences in shape, in both species, the pancreas consists of four parts: the splenic lobe, the head of the pancreas, and the upper and lower lobes. The distal end of the splenic lobe in both species forms a thickened region called the juxtasplenic body. In the brown anole, endocrine islets are found only in the splenic lobe, and there are no islets in the other parts of the embryonic pancreas. In contrast, two clusters were identified in the pancreas of the sand lizard: one within the juxtasplenic body and the smaller one located where the splenic lobe emerges from the head of the pancreas. Both species differ in the topology of the ducts. In the sand lizard, the cystic and hepatic ducts enter the upper lobe of the pancreas, pass into the head of the pancreas, and form the common bile duct, which drains into the duodenum. In the brown anole, the cystic and hepatic ducts run along the upper lobe of the pancreas, then enter the head of the pancreas and form the common bile duct, which drains into the duodenum. Based on similarities between the brown anole, varanid lizards, and snakes, we propose that there is a common developmental sequence in toxicoferans and the adult pancreas of the brown anole represents an intermediate condition between \"typical,\" elongated three-lobed lizard morphology and the shortened and partially compact pancreas of varanid lizards. This adds another grade of variation within the evolutionary pathway leading to the compact pancreas of snakes. On the other hand, the development and the adult-like morphology of the sand lizard pancreas strongly resemble the \"typical\", plesiomorphic, lizard condition. This work contributes to a deeper understanding of squamate anatomy and may shed light on the evolution of the pancreas in this clade.</p>","PeriodicalId":14971,"journal":{"name":"Journal of Anatomy","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144127408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Osteohistology of the Maastrichtian, small-bodied elasmosaurid Kawanectes lafquenianum (Sauropterygia; Plesiosauria).","authors":"M E Pereyra, J O'Gorman, A Chinsamy","doi":"10.1111/joa.14273","DOIUrl":"https://doi.org/10.1111/joa.14273","url":null,"abstract":"<p><p>Plesiosauria is a clade of marine reptiles that thrived from the Late Triassic to the end of the Cretaceous. Among plesiosaurs, the elasmosaurids are particularly notable for their diverse body sizes. Small-sized specimens of Kawanectes lafquenianum exhibit fully closed neuro-central sutures indicating skeletal maturity. To independently assess whether they are indeed small-bodied adults, we analysed the paleohistology of long bones of three differently sized Kawanectes lafquenianum specimens recovered from the La Colonia Formation, Chubut Province, Argentina. The microanatomy of the bones revealed differences in the architectural organization of the hindlimbs and forelimbs, with the humerus being highly remodelled as compared to the femur. Extensive secondary reconstruction in the propodials and ribs suggests a high rate of calcium mobilization, perhaps related to biomechanical stresses. Despite the extensive secondary reconstruction in all the bones studied, primary bone tissue comprising parallel-fibred bone and lamellar bone was identified at the outermost cortex, along with an external fundamental system in the propodial bones of one of the specimens. Overall osteohistology features indicate an adult stage for all the specimens, although it appears that our sample represents individuals at different levels of maturity. Lines of arrested growth were also registered, giving a minimum age of 11 and 14 years for the specimens MPEF-PV 1155 and MPEF-PV 11545, respectively. These results indicated that K. lafquenianum is a small-bodied elasmosaurid (3.8 m-4.2 m in body length). Additionally, the bone microstructure of the postcranial elements reflects interelemental variability. Further research involving additional specimens is needed to explore other palaeobiological aspects of Kawanectes lafquenianum, such as growth dynamics, sexual dimorphisms, locomotion, among others.</p>","PeriodicalId":14971,"journal":{"name":"Journal of Anatomy","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144127487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The elephant backbone: Morphological differences, dorsostability, and vertebral fusions.","authors":"Ruslan I Belyaev, Natalya E Prilepskaya","doi":"10.1111/joa.14270","DOIUrl":"https://doi.org/10.1111/joa.14270","url":null,"abstract":"<p><p>The vertebral column of elephants has several unique features that distinguish them from all other modern-day mammals. In this study, we examine various aspects of the functional morphology and intervertebral mobility of the elephant backbone, comparing it to that of other large herbivorous mammals, as well as to extinct Mammuthus primigenius, M. trogontherii, and Mammut americanum. The elephant vertebral column is characterized by a high degree of dorsostability. All three directions of intervertebral mobility (sagittal and lateral bending, and axial rotation), in all backbone modules, demonstrate the lowest amplitudes of motion known for mammals. In elephants, neck mobility is largely replaced by the mobility of the proboscis; the axial rotation in the thoracic region is not used for maneuvering, and the sagittal flexibility of the lumbar region is practically absent during locomotion. The mobility of the elephant cervical region in the sagittal and frontal planes is low; however, it is still responsible for movements that require significant force, such as tournament fights and breaking tree branches. The lumbosacral joint characterized by sagittal hypermobility in most terrestrial mammals is even less mobile than the intralumbar joints in elephantids. The thoracic-lumbo-sacral region of proboscideans is arch-shaped in lateral view, resulting from the ventral-ward tapering of the vertebral centra (the length along the spinal canal is longer than the length at the ventral side of the centrum). This tapering is most pronounced in the posterior thoracic and lumbar vertebrae. In contrast, the vertebral centra in the middle part of the trunk (T8-T14) are almost rectangular in lateral view. This arch-shaped structure provides static support to the vertebral column, preventing sagging. The absolute length of the spinous processes in proboscideans is comparable to those of the largest bovines and exceeds the lengths of extant rhinoceroses. However, relative to the height of the vertebral centrum, the spinous processes in the withers area of elephants are 2-4 times shorter than those in bovines and rhinoceroses. The profile and inclination angle of the spinous processes differ drastically among different taxa. Despite these differences, we found no significant variations in the sagittal flexibility of the backbone among the different elephantids. We hypothesize that the observed differences may relate to how the arch shape of the backbone is maintained in the posterior part of the thoracolumbar region. In modern-day elephants, dorsostability is primarily supported by a strong supraspinous ligament with short intersegmental portions. In mammoths, this is probably maintained by the linea alba and the abdominal muscles.</p>","PeriodicalId":14971,"journal":{"name":"Journal of Anatomy","volume":" ","pages":""},"PeriodicalIF":1.8,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144127492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}