Evolution of the human birth canal.

It seems puzzling why humans have evolved such a small and rigid birth canal that entails a relatively complex process of labor compared with the birth canal of our closest relatives, the great apes. This study reviewed insights into the evolution of the human birth canal from recent theoretical and empirical studies and discussed connections to obstetrics, gynecology, and orthopedics. Originating from the evolution of bipedality and the large human brain million years ago, the evolution of the human birth canal has been characterized by complex trade-off dynamics among multiple biological, environmental, and sociocultural factors. The long-held notion that a wider pelvis has not evolved because it would be disadvantageous for bipedal locomotion has not yet been empirically verified. However, recent clinical and biomechanical studies suggest that a larger birth canal would compromise pelvic floor stability and increase the risk of incontinence and pelvic organ prolapse. Several mammals have neonates that are equally large or even larger than human neonates compared to the size of the maternal birth canal. In these species, the pubic symphysis opens widely to allow successful delivery. Biomechanical and developmental constraints imposed by bipedality have hindered this evolutionary solution in humans and led to the comparatively rigid pelvic girdle in pregnant women. Mathematical models have shown why the evolutionary compromise to these antagonistic selective factors inevitably involves a certain rate of fetopelvic disproportion. In addition, these models predict that cesarean deliveries have disrupted the evolutionary equilibrium and led to new and ongoing evolutionary changes. Different forms of assisted birth have existed since the stone age and have become an integral part of human reproduction. Paradoxically, by buffering selection, they may also have hindered the evolution of a larger birth canal. Many of the biological, environmental, and sociocultural factors that have influenced the evolution of the human birth canal vary globally and are subject to ongoing transitions. These differences may have contributed to the global variation in the form of the birth canal and the difficulty of labor, and they likely continue to change human reproductive anatomy.

DSP2 for sex determination of miscegenated contemporary hip bones.

The bones of the human pelvis are used in sexual diagnosis generating a high level of accuracy for this type of identification. Morphological and/or morphometric methods are used in the identification of sex. Sexual dimorphism may be affected by ethnic differences in the population. One of the methods for determining sex using hip bone is the 'Diagnose Sexuelle Probabiliste (DSP)' or Probabilistic Sexual Diagnosis (DSP) method. The method presents a new version (Probabilistic Sexual Diagnosis v.2-DSP2) more advisable to be used because it has a more up-to-date database. The objective of this study is to investigate the applicability of the DSP2 method in a population in the Northeast region of Brazil. We used 128 hip bones, 50 female and 78 males, aged between 17 and 101 years, belonging to the Laboratory of Human Identification and Forensic Osteology of the University Federal Government of Pernambuco. The research was conducted between 2019 and 2020 and approved by the Research Ethics Committee of the Federal University of Pernambuco no. 43228015.0.0000.5208. The probability equal to or greater than 0.95 was used as the limit for the determination of sex, and the results were compared with the actual sex of each bone. In the Brazilian collection study, it was observed that the percentage of sex estimation provided by the DSP2 tool using all reference samples was 71.09%, and accuracy was 64.06%. In the analysis of the gender estimate, 82.0% and 78% were obtained for females and males, respectively. Regarding accuracy, it was 64.10% and 55.13% for females and males, respectively. In the contemporary osteological collection of the Northeast region of Brazil, which presents immigrant peoples, we obtained a high index of assertiveness in the DSP2 method. The study concluded that the DSP2 method is important for determining the sex of human skeletons in a miscegenated population.

Hindlimb and pelvic anatomy of Caiman yacare (Archosauria, Pseudosuchia): Myology and osteological correlates with emphasis on lower leg and autopodial musculature.

The anatomy of the archosaurian pelvis and hindlimb has adopted a diversity of successful configurations allowing a wide range of postures during the evolution of the group (e.g., erect, sprawling). For this reason, thorough studies of the structure and function of the pelvic and hindlimb musculature of crocodylians are required and provide the possibility to expand their implications for the evolution of archosaurian locomotion, as well as to identify potential new characters based on muscles and their bony correlates. In this study, we give a detailed description of the pelvic and hindlimb musculature of the South American alligator Caiman yacare, providing comprehensive novel information regarding lower limb and autopodial muscles. Particularly for the pedal muscles, we propose a new classification for the dorsal and ventral muscles of the autopodium based on the organisation of these muscles in successive layers. We have studied the myology in a global background in which we have compared the Caiman yacare musculature with other crocodylians. In this sense, differences in the arrangement of m. flexor tibialis internus 1, m. flexor tibialis externus, m. iliofibularis, mm. puboischiofemorales internii 1 and 2, between Ca. yacare and other crocodylians were found. We also discuss the muscle attachments that have different bony correlates among the crocodylian species and their morphological variation. Most of the correlates did not exhibit great variation among the species compared. The majority of the recognised correlates were identified in the pelvic girdle; additionally, some bony correlates associated with the pedal muscles are highlighted here for the first time. This research provides a wide framework for future studies on comparative anatomy and functional morphology, which could contribute to improving the character definition used in phylogenetic analyses and to understand the patterns of musculoskeletal hindlimb evolution.

Embryonic development of the pelvic girdle and hindlimb skeletal elements in Anilius scytale (Linnaeus, 1758) (Serpentes: Aniliidae).

Anilius scytale is the sister lineage of all other alethinophidian snakes. Morphology of the hind limb complex in adult A. scytale (Aniliidae) has been documented. We herein, for the first time, describe the embryology of the skeletal elements of its hind limb and pelvic girdle and contextualize the evolution of these structures. We identified pregnant females of A. scytale in the Herpetology Collection of the Museu Paraense Emílio Goeldi and separated 40 embryos. The embryos were sequentially staged using external and internal anatomy, collectively comprising a developmental series representing six stages. We cleared-stained one specimen of stages 31, 34, 36, and 37. Using the embryological information gleaned from A. scytale, we reinterpret evidence relating to the ossification of the pelvis and hindlimbs. In A. scytale hindlimb buds develop as transient structures that developed before Stage 30 and regresses in subsequent stages. There is no external or internal evidence of the forelimb or scapular girdle. From Stage 31 onwards the ischium, pubis, ilium, femur and zeugopodial cartilages are visible. Pubis and femur ossify towards the end of embryonic life, and cloacal spurs do not develop in the embryo. Skeletal elements of the hindlimb and pelvic girdle develop initially in the ventral zone of the cloaca-tail region. In subsequent stages the hindlimb and pelvic girdle elements migrate dorsally, with the pubis/ischium positioned medial to the ribs. A similar process may be associated with the achievement of the condition of the pelvic girdle in adults of scolecophidians, pythonids and boids.

Evaluation of the Association between Pelvic Diameters and Pelvic Types on Computed Tomography Images in Healthy Turkish Females / Evaluación de la Asociación entre Diámetros Pélvicos y Tipos de Pelvis en Imágenes de Tomografías Computarizadas en Mujeres Turcas Sanas

SUMMARY: Pelvis contributes to both human locomotion and obstetrics, and normal vaginal delivery is associated with a spacious inlet, a large interspinosus diameter. This paper aimed to measure crucial diameters of pelvic ring, and to determine both the prevalence of pelvic types, and labor types including normal vaginal delivery or caesarean section in Turkish healthy females. Additionally, it was aimed to evaluate presence of relationship between pelvic types and pelvic diameters. Labor shape of subjects was obtained from hospital records. This retrospective study was carried out on 165 healthy subjects aged between 18 and 45 years. Anteroposterior diameter of the pelvic inlet (APDI), anteroposterior diameter of the pelvic outlet, sacrum length (SL), sacrum depth, conjugata vera, obstetrical conjugate, the diagonal conjugate, diameter transversa, diameter bispinous, intertuberous diameter were measured. From these measurements, brim index was calculated and decided to gynecoid, anthropoid and platypelloid type. Also, the andoid type was calculated to the ratio of posterior sagittal diameter of the inlet to conjugata obstetrica. 50.91 % of participants has gynecoid type pelvis, followed by 24.85 % anthropoid type, 14.55 % platypelloid, and 9.70 % android type pelvis. There was a significant difference in APDI, SL, SD, Conjugata vera, Conjugata obstetrica, Conjugata diagonalis, Conjugata transversa, diameter bispinous, diameter intertubercularis and Brim index measurements according to pelvic types. the first degree of narrowing (conjugata vera from 11 to 9) was found in 18 pelvises and 12 pelvises with the pathological degree of narrowing bellonged to the platypelloid type followed by android type pelvis with 6 pelvices. The android type pelvis is not appropriate for natural labor and a good assessment of birth canal can reduce the labor risks. Also, only 7 females who delivered with cesarean have gynecoid type pelvic type. The APDI and SL were significantly lower in subjects having pathological narrowing according to conjugata obstetrica values.

La pelvis contribuye tanto a la locomoción humana como a la obstetricia. El parto vaginal normal se asocia con una entrada espaciosa y un diámetro interespinoso grande. Este artículo tuvo como objetivo medir diámetros cruciales del anillo pélvico y determinar tanto la prevalencia de los tipos pélvicos como los tipos de parto, incluido el parto vaginal normal o la cesárea en mujeres turcas sanas. Además, se buscó evaluar la presencia de relación entre los tipos de pelvis y los diámetros de la pelvis. La forma laboral de los sujetos se obtuvo de los registros hospitalarios. Este estudio retrospectivo se llevó a cabo en 165 mujeres sanas con edades comprendidas entre 18 y 45 años. Se midieron el diámetro anteroposterior de la entrada pélvica (APDPI), el diámetro anteroposterior de la salida pélvica, la longitud del sacro (SL), la profundidad del sacro, la conjugada vera, el conjugado obstétrico, el conjugado diagonal, el diámetro transverso, el diámetro biespinoso y el diámetro intertuberoso. A partir de estas mediciones se calculó el índice del ala y se decidió tipo ginecoide, antropoide y platipoide. Además, el tipo androide se calculó en función de la relación entre el diámetro sagital posterior de la entrada y la conjugada obstétrica. El 50,91 % de los participantes tenía pelvis de tipo ginecoide, seguida del 24,85 % de pelvis de tipo antropoide, el 14,55 % de tipo platipeloide y el 9,70 % de tipo androide. Hubo una diferencia significativa en las mediciones de APDPI, SL, SD, Conjugada vera, Conjugada obstétrica, Conjugada diagonal, Conjugata transversa, diámetro biespinoso, diámetro intertubercular e índice de ala según los tipos de pelvis. El primer grado de estrechamiento (conjugada vera del 11 al 9) se encontró en 18 pelvis y 12 pelvis, siendo el grado patológico de estrechamiento del tipo platipeloide seguido de pelvis tipo androide con 6 pelvis. La pelvis tipo androide no es apropiada para el parto natural y una buena evaluación del canal del parto puede reducir los riesgos. Además, solo 7 mujeres que dieron a luz por cesárea tenían un tipo pélvico de tipo ginecoides. El APDPI y SL fueron significativamente más bajos en mujeres que tenían estrechamiento patológico según los valores obstétricos conjugados.

Somatic and autonomic nerve density of the urethra, periurethral tissue, and anterior vaginal wall: an immunohistochemical study in adult female cadavers.

INTRODUCTION AND HYPOTHESIS: Retropubic procedures may disrupt nerves supplying the pelvic viscera; however, knowledge of pelvic neuroanatomy is limited. We sought to characterize somatic and autonomic nerve density within the urethra, periurethral tissue, and anterior vagina. METHODS: Axial sections were obtained from pelvic tissue harvested from female cadavers ≤24 h from death at three anatomical levels: the midurethra, proximal urethra, and upper trigone. Periurethral/perivesical tissue was divided into medial and lateral sections, and the anterior vagina into middle, medial, and lateral sections. Double immunofluorescent staining for beta III tubulin (ßIIIT), a global axonal marker, and myelin basic protein (MBP), a myelinated nerve marker, was performed. Threshold-based automatic image segmentation distinguished stained areas. Autonomic and somatic density were calculated as percentage of tissue stained with ßIIIT alone, and with ßIIIT and MBP respectively. Statistical comparisons were made using nonparametric Friedman tests. RESULTS: Six cadavers, aged 22-73, were examined. Overall, autonomic nerve density was highest at the midurethral level in the lateral and middle anterior vagina. Somatic density was highest in the external urethral sphincter (midurethra mean 0.15%, SD ±0.11; proximal urethra 0.19%, SD ±0.19). Comparison of annotated sections revealed significant differences in autonomic density among the lateral, medial, and middle vagina at the midurethra level (0.71%, SD ±0.48 vs 0.60%, SD ±0.48 vs 0.70%, SD ±0.63, p=0.03). Autonomic density was greater than somatic density in all sections. CONCLUSIONS: Autonomic and somatic nerves are diffusely distributed throughout the periurethral tissue and anterior vagina, with few significant differences in nerve density among sections analyzed. Minimizing tissue disruption near urethral skeletal muscle critical for urinary continence may prevent adverse postoperative urinary symptoms.

Beyond sex, gender, and other dilemmas: Human pelvic morphology from an integrative context.

Recent research on the pelvis has clarified the flexibility of pelvic bones to manage nearly infinite possibilities in terms of selection and drift, while still maintaining excellent bipedalism. Despite this work, and the studies outlining the diversity of pelvic morphology across the hominin lineage, conversations continue to be stymied by distractions related to purported trade-offs that the different functions the pelvis must either allow for (e.g., parturition) or directly perform (e.g., attachment sites of muscles). Here we show that tight constraints on morphology are not evident in the pelvic variation of multiple human populations. We thus provide further evidence that human pelves are not geometrically similar and that pelvic morphology successfully balances the intersection of population history, active selective, and drift.

Pelvic shape change in adult Japanese macaques and implications for childbirth at old age.

Pelvic morphology exhibits a particular sexual dimorphism in humans, which reflects obstetrical constraints due to the tight fit between neonates and mothers. Huseynov et al. [Proc. Natl. Acad. Sci. U.S.A. 113, 5227-5232 (2016)] showed that in humans, pelvic sexual dimorphism is greatest around the age of highest fertility, and it becomes less marked in association with menopause in females. They proposed that this reflects changes of obstetrical versus locomotor functional demands in females. It remains unknown whether such developmental adjustment of the pelvic morphology is unique to humans. Macaques exhibit human-like cephalopelvic proportions, but they lack menopause and usually maintain fertility throughout adulthood. Here, we track pelvic development in Japanese macaques from neonate to advanced ages using computed tomography-based data. We show that female pelvic morphology changes throughout adult life, reaching the obstetrically most favorable shape at advanced ages rather than around primiparity. We hypothesize that pelvic morphology in Japanese macaques is developmentally adjusted to childbirth at advanced ages, where obstetrical risks are potentially higher than at younger ages. Our data contribute to the growing evidence that the female primate pelvis changes its morphology during the whole lifespan, possibly adjusting for changing functional demands during adulthood.

Where is the optimal plane to mobilize the anterior rectal wall in female patients undergoing total mesorectal excision?

BACKGROUND: Since Heald proposed the total mesorectal excision (TME) procedure, the prognosis of patients with rectal cancer has been significantly improved. But Heald did not specifically describe the anterior surgical plane in female patients. And the surgical plane for mobilizing the anterior rectal wall during TME surgery in female patients remains controversial. AIM: To investigate the anatomy of the female pelvis and identify the optimal plane for mobilizing the anterior rectal wall. METHODS: We retrospectively collected surgical procedure videos and clinical data of female patients diagnosed with middle or low rectal cancer who underwent the TME procedure between January 2020 and October 2022 across six hospitals. The patients were divided into two groups based on the surgical approach used to mobilize the anterior rectal wall: The experimental group was to open the peritoneum at the lowest point of the peritonea reflection and enter the plane for mobilizing, while the control group was cut at 0.5-1 cm above the peritoneal reflection and enter another plan. Then, we compared the preoperative and postoperative information between the two groups. We also dissected and observed ten adult female pelvises to analyze the anatomic structure and compare the entry plane between the two approaches. Finally, we researched the pathological structure between the rectum and the vagina. RESULTS: Finally, 77 cases that met the criteria were included in our study. Our observations revealed that the experimental group underwent a smooth procedure, entering the plane amidst the mesorectal fascia and adventitia of the vagina, whereas the control group entered the plane between the vaginal adventitia and muscle layers. Compared to the control group, the experimental group showed a significant decrease in intraoperative bleeding [22.5 (19.5-50) mL vs 17 (5-20) mL, P = 0.01], as well as a shorter duration of hospitalization [9 (7-11.25) d vs 7 (6-10) d, P = 0.03]. Through the examination of surgical videos and cadaveric studies, we discovered that Denonvilliers' fascia is absent in females. Additionally, pathological sections further revealed the absence of Denonvilliers' fascia in females, with only loose connective tissue present between the mesorectal fascia and adventitia of the vagina. CONCLUSION: The plane amidst the mesorectal fascia and vaginal adventitia is the optimal surgical plane to mobilize the anterior rectal wall for female patients undergoing the TME procedure.

Pelvic + Anatomy: A new interactive pelvic anatomy model. Prospective randomized control trial with first-year midwife residents.

Detailed knowledge of female pelvic floor anatomy is essential for midwifery and other professionals in obstetrics. Physical models have shown great potential for teaching anatomy and enhancing surgical skills. In this article, we introduce an innovative physical anatomy model called "Pelvic+" to teach anatomical relationships in the female pelvis. The Pelvic+ model's value was compared to a traditional lecture in 61 first-year midwifery students randomly allocated to either the Pelvic+ (n = 30) or a control group (n = 32). The primary outcome measure was a quiz comprised of 15 multiple choice questions on pelvic anatomy. Participants were assessed at baseline (Pre-Test), upon completion of the intervention (Post-Test1) and 4 months afterward (Post-Test2). Satisfaction with the approach was assessed at Post-Test1. Increase in knowledge was greater and the approach more accepted among resident midwives when Pelvic+ was used instead of standard lectures. Four months after the intervention, the improvement in knowledge was preserved in the Pelvic+ group. This randomized study demonstrates that the Pelvic+ simulator is more effective than classical learning for pelvic anatomy education, and offers a higher level of satisfaction among students during the educational process. Medical students training in obstetrics and gynecology, or any professional who specializes in the female pelvic floor might also benefit from incorporation of the Pelvic+ model into their training program.

Changes in plasticity of the pelvic girdle from infancy to late adulthood in Homo sapiens.

Previous research on the effects of body mass on the pelvic girdle focused mostly on adult females and males. Because the ontogenetic plasticity level in the pelvis remains largely unknown, this study investigated how the association between body mass index (BMI) and pelvic shape changes during development. It also assessed how the large variation in pelvic shape could be explained by the number of live births in females. Data included CT scans of 308 humans from infancy to late adulthood with known age, sex, body mass, body stature, and the number of live births (for adult females). 3D reconstruction and geometric morphometrics was used to analyze pelvic shape. Multivariate regression showed a significant association between BMI and pelvic shape in young females and old males. The association between the number of live births and pelvic shape in females was not significant. Less plasticity in pelvic shape in adult females than during puberty, perhaps reflects adaptation to support the abdominopelvic organs and the fetus during pregnancy. Non-significant susceptibility to BMI in young males may reflect bone maturation accelerated by excessive body mass. Hormonal secretion and biomechanical loading associated with pregnancy may not have a long-term effect on the pelvic morphology of females.

Consensus on the Gemelli terminology of surgical anatomy for radical hysterectomy.

OBJECTIVES: To report on a consensus survey of experts on a recently proposed simplified nomenclature of surgical anatomy of the female pelvis for radical hysterectomy. The aim was to standardize surgical reports in clinical practice and understanding of the techniques in future surgical literature. METHODS: The anatomical definitions were included in 12 original images taken at the time of cadaver dissections. Denomination of the corresponding anatomical structures was based on the nomenclature recently proposed by the same team. A three step modified Delphi method was used to establish consensus. After a first round of online survey, the legends of the images were amended to respond to the comments of the experts. Second and third rounds were performed. Consensus was defined as a yes vote to each question regarding the images provided, and 75% was defined as the cut-off for agreement. Comments justifying the no votes were taken into account to amend the set of images and legends. RESULTS: A group of 32 international experts from all continents was convened. Consensus exceeded 90% for all five images documenting the surgical spaces. Consensus ranged between 81.3% and 96.9% for the six images documenting the ligamentous structures surrounding the cervix. Finally, consensus was lowest (75%) for the most recently defined denomination of the broad ligament (lymphovascular parauterine tissue or upper lymphatic pathway). CONCLUSION: Simplified anatomic nomenclature is a robust tool to describe the surgical spaces of the female pelvis. The simplified definition of ligamentous structures reached a high level of consensus, even if the terms paracervix (instead of lateral parametrium), uterosacral ligament (replaced by rectovaginal ligament), vesicovaginal ligament, and lymphovascular parauterine tissue remain matters of debate.

Nerve relationships to the sacrospinous ligament: application to suspension procedures and transgluteal approaches for nerve repair and tumor removal with three case illustrations.

BACKGROUND: Transvaginal suspension procedures often use the sacrospinous ligament (SSL), which attaches onto the ischial spine (IS). However, nerve-related sequelae (e.g., sciatic nerve injury) following such procedures have been reported. Therefore, the current anatomical study was performed to better understand these relationships. Additionally, three case illustrations of patients with injury to the sciatic nerve following sacrospinous ligament suspension procedures are included to exemplify the significance of a thorough knowledge of this anatomy. METHODS: In 20 human adult cadavers (40 sides), a gluteal dissection was performed to expose the IS and SSL and regional nerves near the greater sciatic foramen. Measurements between the IS and SSL were made between these structures and surrounding nerves. RESULTS: The average distance between the IS and sciatic nerve was 1.4 cm. From this bony part, the average distance to the S1 and S2 ventral rami was 3.1 cm and 1.9 cm, respectively. From the IS to the lumbosacral trunk, pudendal nerve, nerve to obturator internus, and superior gluteal nerve, the mean distance was 4 cm, 0.5 cm, 0.7 cm, and 4.5 cm, respectively. From the SSL to the lumbosacral trunk, S1 ventral ramus, and S2 ventral ramus, there was an average distance of 4.2 cm, 1.6 cm, and 0.8 cm, respectively. Statistically, in females, the distances from the IS and SSL to the sciatic nerve, lumbosacral trunk, superior gluteal nerve, and S1 and S2 ventral rami were shorter when compared to males. CONCLUSION: An improved understanding of the relationship between the SSL and IS and nerves near the greater sciatic foramen can lead to fewer intraoperative complications during approaches to various peripheral nerves in this region. Lastly, these relationships might help better understand the nerve injuries following pelvic suspension procedures that use the SSL.

Three-dimensional reconstruction of the innervation of the female pelvis: A review of current methods.

The three-dimensional (3D) reconstruction of tissues is a valuable approach for elucidating the anatomy of nerves and plexuses, which are often microscopic in nature and therefore difficult to fully appreciate using gross dissection approaches alone. A common workflow which can be used to generate such 3D models has yet to be comprehensively described. This study aimed to review 3D reconstruction methodologies and findings related to human female pelvic innervation to determine whether there is an optimal methodology and identify the limitations of these approaches. A comprehensive literature review was conducted using keywords including 3D reconstruction, human female pelvic nerves, and innervation. Twenty relevant articles published between 2003 and 2019 were selected for review. The 3D reconstruction of female pelvic innervation generally follows two workflows involving either immunohistochemistry (IHC) (n = 16) or magnetic resonance imaging (MRI) (n = 4). There were commonalities among the general steps reported for 3D tissue reconstruction across these two imaging methodologies. Notably, there was some variability in study methodology across the studies reviewed, suggesting there is not a clear best practice for the reconstruction of these tissues. Information that generates 3D mapping of innervation has important clinical applications, such as informing and optimizing surgical approaches to avoid damage to local innervation. IHC and MRI-based approaches are both feasible for the reconstruction of pelvic innervation, though there are advantages and disadvantages to both. Information from this review can be used to help inform the development of 3D models of female pelvic innervation in the future.

The Middle Rectal Artery: Revisited Anatomy and Surgical Implications of a Neglected Blood Vessel.

BACKGROUND: Although the middle rectal artery is a relevant anatomical landmark for rectal resection and lateral lymph node dissection, descriptions of this entity are highly divergent. OBJECTIVE: Dissection, visualization, morphometry, and 3-dimensional reconstruction of the middle rectal artery to facilitate its management in surgery. DESIGN: Macroscopic dissection, histologic study, morphometric measurements, and virtual modeling. SETTING: University laboratory of applied surgical anatomy. PATIENTS: This study includes formalin-fixed hemipelvis specimens (n=37) obtained from body donors (age, 67-97 y). MAIN OUTCOME MEASURES: The main outcome measures are photo documentation of origin, trajectory, diameter, and branching pattern; immunolabeling of lymphatics; and 3-dimensional reconstruction of the middle rectal artery. RESULTS: The middle rectal artery was present in 71.4% of body donors (21.4% bilateral, 50% unilateral), originated from the anterior division of the internal iliac artery, and branched either from the internal pudendal artery (45.5%), the inferior gluteal artery (22.7%), the gluteal-pudendal trunk (22.7%), or a trifurcation (9.1%). One to 3 branches of varying diameters (0.5-3.5 mm) entered the mesorectum from the ventrolateral (35.7%), lateral (42.9%), or dorsolateral (21.4%) aspect. The middle rectal artery was accompanied by podoplanin-immunoreactive lymphatic vessels and gave off additional branches (81.8%) to the urogenital pelvic organs. Three-dimensional reconstruction revealed the complex course of the middle rectal artery from the pelvic sidewall through the pelvic nerve plexus and parietal pelvic fascia into the mesorectum. LIMITATIONS: Findings retrieved from body donors may be prone to age- and fixation-related processes. CONCLUSIONS: The investigation disclosed the rather high prevalence of the middle rectal artery, its 3-dimensional topographic anatomy, and its proximity to the autonomic pelvic nerves. These features play a role in the surgical management of this blood vessel. The data provide the anatomical rationale for the lateral lymphatic spread of rectal cancer and an anatomical basis for nerve-preserving lateral lymph node dissection.

Morphodynamic study of the corona mortis using the SimLife® technology.

PURPOSE: Open book pelvic ring fractures are potentially life-threatening, due to their instability and major hemorrhage risk. During the open reduction and internal fixation, the pelvic approach remains a technical challenge, as the surgeon wants to prevent any iatrogenic damage of the vascular loop located in the retro-pubic area called corona mortis (CMOR). Recently, the cadaver perfused SimLife® technology has been developed to improve the surgeon training, out of the operating room. This study aimed to compare two models of cadaveric dissection, to assess the interest of the perfused SimLife® in providing dynamic aspect of anatomy in the identification of CMOR and its topography. METHODS: Twelve human cadaveric pelvises have been dissected, following two protocols. 12 hemi-pelvises of the dissections were performed without perfusion (Model A), whereas the 12 other hemi-pelvises have been prepared with the SimLife® pulsatile perfusion (Model B). The prevalence and morphologic parameters determined: length, diameter and distance between the CMOR and the pubic symphysis. RESULTS: The CMOR has been found in 66.67% of the cases. The length, the diameter, and the distance between the CMOR and the pubic symphysis were significantly higher in model B (respectively p = 0.029, p = 0.01, and p = 0.022). CONCLUSION: These results suggest that the CMOR is easier to identify and to dissect with the SimLife® perfusion. As part of the surgical training of any trauma surgeon, this model could help him to keep in mind the CMOR topography, to improve the open book lesion management.

[Cognition and reflection on the "lateral ligament of rectum"].

As total mesorectal excision (TME) for rectal cancer is widely carried out in China, lateral ligament of rectum, as an important anatomical structure of the lateral rectum with certain anatomical value and clinical significance, has been the focus of attention. In this paper, by comparing and analyzing the characteristics about ligaments of the abdomen and pelvis, reviewing the membrane anatomy and the theory of primitive gut rotation, and combining clinical observations and histological studies, the author came to a conclusion that lateral ligament of rectum does not exist, but is only a relatively dense space on the rectal side accompanied by numerous tiny nerve plexuses and small blood vessels penetrating through it.

The usability of the ratio of bi-humerus breadth to maximum pelvic breadth in sex estimation.

BACKGROUND: Although sex can be determined with high accuracy in forensic anthropology, additional parameters are still required. AIM: To estimate with known simple statistical methods, the usability of the bi-humerus/maximum pelvic breadth ratio in sex estimation. SUBJECTS AND METHODS: Bi-humerus breadth and maximum pelvic breadth were measured using the topogram images (196 males, 171 females), the ratio between them was calculated. We examined the usability of the ratio of the distance between the lateral edges of the right and left humeral heads to the maximum distance between the two most lateral parts of the iliac crests in sex estimation. RESULTS: There was significant difference in the bi-humerus breadth and "bi-humerus breadth/maximum pelvic breadth" according to sex. The greatest breadth of the pelvis was higher in females, yet the difference was not statistically significant. The ratio yielded 80.6%-90.3% accuracy for females and 73.6%-74.7% for males, depending on arm position. CONCLUSIONS: The obtained data may contribute to the development of formulas created with metric measurements used in sex estimation. This can be used as a parameter to help in estimating the sex of skeletal remains found as a whole or excavated without losing their integrity, and also in the reconstruction of body structure.

The appendicular myology of Stegoceras validum (Ornithischia: Pachycephalosauridae) and implications for the head-butting hypothesis.

In this study, we use an exceptional skeleton of the pachycephalosaur Stegoceras validum (UALVP 2) to inform a comprehensive appendicular muscle reconstruction of the animal, with the goal of better understanding the functional morphology of the pachycephalosaur postcranial skeleton. We find that S. validum possessed a conservative forelimb musculature, particularly in comparison to early saurischian bipeds. By contrast, the pelvic and hind limb musculature are more derived, reflecting peculiarities of the underlying skeletal anatomy. The iliotibialis, ischiocaudalis, and caudofemoralis muscles have enlarged attachment sites and the caudofemoralis has greater leverage owing to the distal displacement of the fourth trochanter along the femur. These larger muscles, in combination with the wide pelvis and stout hind limbs, produced a stronger, more stable pelvic structure that would have proved advantageous during hypothesized intraspecific head-butting contests. The pelvis may have been further stabilized by enlarged sacroiliac ligaments, which stemmed from the unique medial iliac flange of the pachycephalosaurs. Although the pubis of UALVP 2 is not preserved, the pubes of other pachycephalosaurs are highly reduced. The puboischiofemoralis musculature was likely also reduced accordingly, and compensated for by the aforementioned improved pelvic musculature.

Scientists isolate the genes that shape the human pelvis.

Embryonic tissue samples reveal how pelvis shape-primed for bipedalism-comes to life.