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Objectives Obstetric demands have long been considered in the evolution of the pelvis, yet consideration of the interaction of pregnancy, the pelvis, and the gastrointestinal tract (gut) is lacking. Here, we explore sex differences in the relationship of gut volume with body size and pelvic dimensions. Materials and methods Computed tomography (CT) scans of living adult Homo sapiens (46 females and 42 males) were obtained to measure in vivo gut volume (GV) and to extract 3D models of the pelvis. We collected 19 3D landmarks from each pelvis model to acquire pelvic measurements. We used ordinary least squares regression to explore relationships between GV and body weight, stature, and linear pelvic dimensions. Results The gut-pelvis relationship differs between males and females. Females do not exhibit significant statistical correlations between GV and any variable tested. GV correlates with body size and pelvic outlet size in males. GV scales with negative allometry relative to body weight, stature, maximum bi-iliac breadth, inferior transverse outlet breadth, and bispinous distance in males. Discussion The lack of association between GV and body size in females may be due to limits imposed by the anticipation of accommodating a gravid uterus and/or the increased plasticity of the pelvis. The pattern of relationship between GV and the pelvic outlet suggests the role of the bony pelvis in supporting the adominal viscera in females may be small relative to its role in childbirth. We conclude that gut size inference in fossil hominins from skeletal proxies is limited and confounded by sexual dimorphism.

The region anterior to the anal canal in women is composed of intertwined smooth and skeletal muscles. The present study aimed to clarify skeletal muscle morphology in the anterior region of the anal canal. The pelvic floor muscles of 28 pelvic halves from 16 female cadavers (mean age 79.75 years) were dissected from the inferior aspect to examine the perineal muscles, followed by midline transection and dissection from the inner surface to examine the pelvic outlet muscles. The bulbospongiosus muscle was found to be attached to the lateral surface of the external anal sphincter. The superficial transverse perineal muscle crossed superiorly to the bulbospongiosus and coursed medially toward its contralateral muscle bundle deep to the anterior portion of the external anal sphincter. The superficial transverse perineal muscle formed the middle sling. From the medial aspect, the anterior part of the levator ani was divided into anterior and posterior bundles to form the anterior and posterior slings, respectively. This study proposes that three muscular slings could be important in supporting the pelvic floor in women. In addition, this study shows that the anterior skeletal muscular wall of the anal canal is composed of the anterior muscle bundle of the levator ani, superficial transverse perineal, and proper external anal sphincter muscles.

Homo sapiens is variable in number of sacral vertebrae, and this variability can lead to obstetrical complication. This study uses the comparative method to test the hypothesis that sacral variability in H. sapiens is associated with absence of a tail. Three species of lagomorphs are studied: Ochotona princeps (N = 271), which is tailless, and Lepus californicus (N = 212) and Sylvilagus audubonii (N = 206), which have tails. Results show that O. princeps has (1) higher diversity index for number of sacral vertebrae (0.49) compared to L. californicus (0.25) and S. audubonii (0.26) and (2) significantly higher percentage of individuals with the species-specific nonmodal number of sacral vertebrae (43.9%) compared to L. californicus (14.2%) and S. audubonii (15.5%). Comparison of H. sapiens (N = 1,030; individuals of age 20-39 years) with O. princeps shows similarities between the species in diversity index (also 0.49 in H. sapiens) and percentage of individuals with nonmodal number of sacral vertebrae (37.3% in H. sapiens). Homeotic transformation best explains the results. H. sapiens and O. princeps show propensity for caudal shift at the sacral-caudal border (i.e., homeotic transformation of the first caudal vertebra to a sacral vertebra). Caudal and cranial shift among presacral vertebrae increases or decreases this propensity, respectively. Increase in number of sacral vertebrae in H. sapiens by homeotic transformation reduces pelvic outlet capacity and can be obstetrically hazardous. Anat Rec, 300:798-809, 2017. © 2017 Wiley Periodicals, Inc.

Considerable research has shown that modern human pelvic dimensions, especially of the birth canal, are sexually dimorphic. Studies also suggest that females with younger ages-at-death have narrower canal dimensions than those who die at older ages, possibly due to continued independent growth of the pubis. A recent examination of this pattern argued that it is unlikely that these differences relate to mortality, but the source of the difference in pelvic dimensions with age remains unresolved. We use pelvic dimensions to assess differences in magnitudes of morphological integration between adult females and males across ages-at-death. We first ascertain whether the sexes have different strengths of integration, and then assess if differences in magnitudes of integration are associated with age-at-death. Pelvic dimensions of all groups were moderately integrated. Females and males have similar magnitudes of integration, and there is no change in the strength of integration with age. Examining individual regions of the pelvis indicates that the ilium, pubis, and pelvic inlet and outlet have stronger integration than the overall pelvis. This was particularly true of the pelvic outlet, which demonstrated the strongest integration. Our findings suggest that regions of the pelvis are more strongly integrated internally, and less integrated with each other, which would allow for proportional growth among regions of the pelvis with age that do not affect its overall integration. No single region of the pelvis appears to be motivating the difference in pelvic dimensions between age groups. We further consider the implications of these findings on evolutionary constraints. Anat Rec, 300:666-674, 2017. © 2017 Wiley Periodicals, Inc.

Cephalopelvic disproportion is common among Africans and is a major cause of maternal and perinatal mortality and morbidity. As the dimensions of the pelvis may vary between populations and according to stature and age, they need to be considered during childbirth and also in the planning and performance of pelvic and perineal procedures. The aim of this study was to assess the possible variations in the dimensions of the intact pelvic canal in South Africans and their implications. Eighty intact cadaver pelves, belonging to 40 white South Africans (20 males and 20 females) and 40 black South Africans (20 males and 20 females) were used for both metric and geometric morphometric analyses. Pelvic inlet shapes did not differ significantly between groups but pelvic inlet and midpelvic dimensions were the greatest in white South Africans and females. The pubic symphyseal length was the greatest in white males and the smallest in black females, resulting in a smaller pelvic cavity anteriorly than for white females. Pelvic outlet shapes varied significantly between sexes in white South Africans and between white and black males. Females presented with the greatest dimensions. Black South African females presented with an elongated anteroposterior outlet diameter. Certain transverse pelvic diameters correlated positively with age in white males and with height in females. In planning childbirth options, the smaller pelvic inlet of black females and stature-dependent diameters should be considered. Pelvic and perineal surgery may be technically more challenging because of smaller pelvic dimensions in black South Africans, especially in males.

The observation of severe pelvic malformations in Eurasian lynx (Lynx lynx) from a population reintroduced to Switzerland raised the question as to whether inbreeding may contribute to the development of congenital pelvic malformations. We aimed at providing baseline data on the pelvic morphology of Eurasian lynx from the reintroduced populations in Switzerland, at assessing potential differences in pelvic conformation between the two main Swiss populations, among age classes and between sexes, and at detecting pelvic anomalies. We performed measurements of 10 pelvic parameters on the radiographs of 57 lynx of both sexes and different ages taken from 1997-2015. We calculated two ratios (vertical diameter/acetabula; sagittal diameter/transversal diameter) and two areas (pelvic outlet and inlet) to describe the shape of the pelvis. Our results showed that the Eurasian lynx is a mesatipelvic species, with a pelvis length corresponding to approximatively 20% of the body length. We found no statistically significant differences between the two examined populations but observed growth-related pelvis size differences among age groups. Sexual dimorphism was obvious in the adult age group only: two parameters reflecting pelvic width were larger in females, likely to meet the physiological requirements of parturition. By contrast, pelvis length, conjugata vera, diagonal conjugata, vertical diameter and sagittal diameter were larger in males, in agreement with their larger body size. Accordingly, the ratio between the sagittal and transversal diameters was significantly larger in males, i.e. adult males have a different pelvic shape than adult females. Furthermore, pelvimetry highlighted one adult individual with values outside the calculated reference range, suggesting a possible congenital or developmental pathological morphology of the internal pelvis. Our work generated baseline data of the pelvic morphology including growth and sexual dimorphism of the Eurasian lynx. These data could also be useful for estimating age and sex in skeletal remains.

Background: Vertical pelvic ring displacement (VPRD) is a serious injury and needs assessment. Pelvic outlet radiographs are routinely taken. However, relationship of radiographic and actual VPRD is still in question. Thus, measurement of VPRD from pelvic radiographs was studied. Materials and Methods: 2 dry pelvic bones and 1 sacrum from same cadaver was reconstructed to be the pelvic ring. Five specimens were enrolled. 10, 20 and 30 mm vertical displacement of right pelvic bone was performed at levels of sacroiliac joint and pubic symphysis for representing right VPRD. Then, the pelvis was set sacral inclination at 60° from X-ray table for outlet and anteroposterior pelvic radiographs. Right VPRD was measured by referring to superior most pelvic articular surface of both sacroiliac joints and sacral long axis. Radiographic VPRD and actual displacement were analyzed by Pearson correlation coefficient at more than 0.90 for the strong correlation and strongly significant simple regression analysis was set at P < 0.01. Results: Radiographic VPRD from outlet and anteroposterior pelvic views at 10 mm actual displacement were 20.12 ± 1.98 and 4.08 ± 3.76 mm, at 20 mm were 40.31 ± 1.97 and 9.94 ± 7.27 mm and at 30 mm were 58.56 ± 2.53 and 11.29 ± 2.89 mm. Statistical analyses showed that radiographic VPRD from pelvic outlet view is 1.95 times of actual displacement with strong correlation at 0.992 coefficient and strongly significant regression analysis (P < 0.001) with 0.984 of R[2] value. Whereas, the measurement from anteroposterior pelvic radiograph was not strongly significant. Conclusion: Pelvic outlet radiograph provides efficient measurement of VPRD with 2 times of actual displacement.

The retroperitoneal tumors (RPTs) in the pelvis, also known as presacral tumors, are derived from the retroperitoneum, mostly or wholly located in the pelvic cavity, whereas excluding tumors that originate from internal organs such as the bladder, prostate, adnexa of uterus, colon, and rectum. Due to the presence of wide spaces between the pelvic peritoneum and presacral space, pelvic side walls, and pelvic diaphragm, soft tissue tumors originating from these spaces may be located posteriorly, laterally, inferiorly, or even anteriorly to peritoneum. All tumors are mostly or wholly located within true pelvis between the pelvic inlet (encircled by pubic joint, iliopubic line, and the sacral promontory) and pelvic outlet (comprised of coccyx, ischial tuberosity, and pubic arch). The tumor may partially spread to the lower abdomen and bilateral iliac fossa and even to the buttocks and perineum. 9.1% of patients with pelvic RPTs develop diffusion and metastasis, including peritoneal implantation, lymph node metastasis, and liver metastasis.

Intra-abdominal and intra-pelvic pathologies initially presenting in extra-abdominal/pelvic locations is unusual. This spread predominantly occurs with infectious processes to sites including the buttock, thigh, and calf. The routes of extension into adjacent anatomically weak compartments include the pelvic outlet, greater sciatic foramen, obturator foramen, inguinal or femoral canal, weak bones, or along nerves and blood vessels. Malignant neoplasms of the appendix, while extremely rare and accounting for only 0.4% of all gastrointestinal cancers, is one of the intra-abdominal pathologies that can spread via these routes. Adenocarcinoma of the appendix accounts for 10-20% of primary appendiceal tumors. They usually present as acute appendicitis or as a right lower quadrant abdominal mass when associated with a mucocele. We report the unique case of mucinous appendiceal adenocarcinoma in a 57-year-old male who initially presented with a right thigh mass secondary to extension of the neoplasm from the right lower quadrant through the femoral canal. A similar presentation of a mucinous appendiceal cystadenoma has been previously reported, however, to our knowledge, this is the first case of a malignant appendiceal tumor extending into the thigh. We review the literature and discuss imaging findings and treatment of this tumor.

Intra-abdominal disease can present as an extra-abdominal abscess and can follow several routes, including the greater sciatic foramen, obturator foramen, femoral canal, pelvic outlet, and inguinal canal. Nerves and vessels can also serve as a route out of the abdomen. The psoas muscle extends from the twelfth thoracic and fifth lower lumbar vertebrae to the lesser trochanter of the femur, which means that disease in this muscle group can migrate along the muscle, out of the abdomen, and present as a thigh abscess. We present a case of a primary pelvic staphylococcal infection presenting as a thigh abscess. The patient was a 60-year-old man who presented with left posterior thigh pain and fever. Physical examination revealed a diffusely swollen left thigh with overlying erythematous, shiny, and tense skin. X-rays revealed no significant soft tissue lesions, ultrasound was suggestive of an inflammatory process, and MRI showed inflammatory changes along the left hemipelvis and thigh involving the iliacus muscle group, left gluteal region, and obturator internus muscle. The abscess was drained passively via two incisions in the posterior left thigh, releasing large amounts of purulent discharge. Subsequent bacterial culture revealed profuse growth ofStaphylococcus aureus. The patient recovered uneventfully except for a moderate fever on the third postoperative day.

Minimally invasive surgical techniques may decrease length of stay, operative duration and blood loss, and postoperative pain. Numerous technical challenges and concerns surround the placement of percutaneous pedicle screws at the lumbosacral level. Maximization of screw triangulation, bicortical purchase, and rostral bias toward the sacral promontory has been shown repeatedly to stabilize lumbosacral segment instrumentation and maximize pullout strength. Because of the unique anatomy, conventional anteroposterior (AP) and lateral radiographic views are relatively less reliable at determining screw depth and penetration of the sacral cortex. Percutaneous sacral pedicle fixation using AP and lateral 2-dimensional fluoroscopy is complicated by the variable contour of the sacral alae and promontory. The pelvic inlet view is ideal for visualization of the ventral screw extent and is obtained by directing 45-degree cephalad and 0-degree mediolateral, with adjustments aligning the patient's pelvic brim. The modified pelvic outlet view is obtained with the trajectory axis being directed 45-degree caudal from the AP plane. This aligns the pubic symphysis with the second sacral vertebrae providing visualization of the superior boundary of the S1-bony neural foramen and any inferior wall pedicle breaches. The authors describe this reliable fluoroscopic technique and their clinical experience with percutaneous S1-screw placement.

The bony pelvis anatomy is highly variable. This study aims to examine the relationship between anthropometric measurements and the size of the adult female bony pelvis. Three-dimensional points of all pertinent landmarks of 96 adult female bony pelvises were obtained and the true conjugate, interspinous distance, intertuberous distance, and pelvic inlet and outlet areas were calculated. The relationship between these measurements and height and multiple anthropometric measurements were evaluated using Pearson’s correlation coefficient (r). Multiple anthropometric measurements were significantly correlated with the true conjugate and pelvic inlet and outlet areas, but not with the interspinous or intertuberous widths. Height had a greater correlation with pelvic areas than any other anthropometric measure considered, even after controlling for race. There were no significant differences in pelvic areas between races. Height and other anthropometric measurements were significantly correlated with the true conjugate and pelvic inlet and outlet areas.

PURPOSE: The aim of the study was to utilize the obtained data for differentiation of normal and pathologically altered bulbourethral glands in rabbits with regard to using this animal species as a model for studying diseases in this organ in humans. MATERIAL AND METHODS: Ten sexually mature healthy male white New Zealand rabbits, 12 months old, weighed 2.8−3.2 kg were investigated. The animals were anesthetized. Scans were done at 2 mm intervals and the image reconstruction was three-dimensional. RESULTS: Rabbit bulbourethral glands were observed as a transversely oval homogeneous, relatively hyperdense structure against the surrounding soft tissues. They are visualized in the transverse cut of the pelvic outlet in the plane through the cranial part of cg2, the body of ischium, cranially to tuber ischiadicum and dorsally to the caudal part of symphysis pubis –sciatic arch. The glandular margins are adequately distinguished from the adjacent soft tissue structures. The density of the rabbit bulbourethral glands was similar to this of the soft tissues. CONCLUSION: The data obtained by the computed tomographic imaging of the rabbit bulbourethral glands could be used as an anatomical reference in the diagnosis and interpretation of imaging findings of various pathological states of the gland in this species, as well as in utilization of the rabbit as an animal model for studying diseases of this organ in humans, particularly diverticula, stenosis, lithiasis and valves.

I posit that humans appear to be the only species that develops otitis media. If animals in the wild had developed middle-ear disease to any significant degree, they would have been selected out during evolution because they would not have survived their predators given the associated hearing loss. Why do humans have otitis media? Evolution has had a significant impact. It is well known that humans are born 12 months too early, which is the result of adaptations to bipedalism and our big brain that, over time, resulted in a relatively small female pelvic outlet compared with nonhuman primates. As a consequence of too early a birth, not only is our immune system immature, but the eustachian tube is too short and floppy in the first year of life. But why is otitis media still common in older individuals? What other adaptation is uniquely human? We developed speech that was associated with descent of the larynx and hyoid bone, which, along with a decrease in prognathism (i.e., facial flattening), resulted in a change in palatal morphology as compared with other primates. Comparative anatomic and physiologic studies have demonstrated significant differences between humans and monkeys, especially in the muscles of the eustachian tube. Paradoxic constriction, as apposed to dilation, on swallowing is a common tubal dysfunction in humans and certain monkey models with chronic middle-ear effusion. My hypothesis is that chronic otitis media with effusion in patients with tubal constriction is a consequence of adaptation for speech and that, most likely, the levator veli palatini muscle is the cause.

Vertically unstable and complex bilateral sacral fractures are a result of high-energy mechanisms that are often associated with other injuries1-19. Vertically unstable sacral fractures result in the separation of the hemipelvis from the lumbar spine, whereas complex bilateral fractures result in a complete dissociation of the appendicular and axial skeleton. Recently, the surgical treatment algorithm for these fractures has changed, with an increasing number of surgeons advocating for the use of spinopelvic fixation or triangular osteosynthesis, a combination of spinopelvic fixation along with sacroiliac or transsacral screw fixation, to increase the stability of the construct and to allow for early weight-bearing with decreased concern for secondary displacement1-19. ### Osseous and Ligamentous Anatomy The sacrum is a rhomboid-shaped bone consisting of five fused segments that is the lowest functional section of the spinal column and acts as the keystone of the pelvic ring20. When force enters the sacrum, it propagates laterally across the sacroiliac joints into the pelvis. Because of the shape of the sacrum and the orientation of the sacroiliac joints, axial forces stabilize the sacroiliac articulation in the pelvic outlet plane; however, in the pelvic inlet plane, the osseous configuration lacks inherent stability. The interosseous ligaments and posterior sacroiliac ligaments provide the majority of the intrinsic stability. Comparatively, the sacrospinous and sacrotuberous ligaments provide the extrinsic stability21. The osseous architecture of the sacrum can be …

Background: A difficult vaginal birth is known to be one of the causes of damage to the pelvic floor muscles. Prolonged second stage of labour is thought to be one of the implicating factors in this damage. If the muscles of the pelvic floor were hypertrophied in response to repetitive high impact training, then the ‘suspected phenomenon’ of a more difficult childbirth for very athletic women might be related to these muscles reducing pelvic floor compliance. Aim: To document the muscle morphology of the pelvic floor using magnetic resonance imaging (MRI) in a group of nulliparous female athletes and to compare this to the findings in a similar group of age-matched nulliparous nonathletic women. Methods: Static Magnetic Resonance (MR) imaging of the pelvic floor was performed with particular reference to the muscle morphology of levator ani and puborectalis. The cross-sectional area of the urogenital hiatus and the diameter of the bony pelvic outlet were also assessed. Results: Significant differences in the cross-sectional area and width of the pelvic floor muscles, measured in the line of the anal canal, were found between the athletic group and the controls. There were no differences found between the two groups in the cross-sectional area of the urogenital hiatus, and the adequacy of the pelvic outlet was established with reference to normative data. Conclusions: The differences shown in the pelvic floor muscles in the athletes and nonathletes provide a focus for further research into this area. This change might influence the function of the pelvic floor muscles in this subgroup of women.

Cellular angiofibromas (CAF) are rare, benign, soft tissue/stromal lesions first described by Nucci et al. in 1997. These masses are well circumscribed, typically small (< 6 cm), and occur mainly in the vulvar region in women and the inguinoscrotal region in men. We present a case of a 60-year-old male who was found to have a very large (20 cm × 13.5 cm × 6 cm) lesion occupying the deep pelvis bridging the pelvic outlet and involving the perineum. Because of diagnostic uncertainty and significant symptomatology, the mass was ultimately resected en bloc with the rectum and anus. Final pathology revealed a large multi-lobulated CAF. This tumor is the largest CAF reported in the literature to date. Furthermore, this mass involved the deep male pelvis with extension between two anatomic compartments which has not been previously described.

The purpose of this study was to assess the impact of different positions on pelvic diameters by comparing pregnant and nonpregnant women who assumed a dorsal supine and kneeling squat position.In this cohort study from a tertiary referral center in Germany, we enrolled 50 pregnant women and 50 nonpregnant women. Pelvic measurements were obtained with obstetric magnetic resonance imaging pelvimetry with the use of a 1.5-T scanner. We compared measurements of the depth (anteroposterior (AP) and width (transverse diameters) of the pelvis between the 2 positions.The most striking finding was a significant 0.9-1.9 cm increase (7-15%) in the average transverse diameters in the kneeling squat position in both pregnant and nonpregnant groups. The average bispinous diameter in the pregnant group increased from 12.6 cm ± 0.65 cm in the supine dorsal to 14.5 cm ± 0.64 cm (P.0001) in the kneeling squat; in the nonpregnant group the increase was from 12 cm ± 0.76 cm to 13.9 cm ± 1.04 cm (P.0001). The average bituberous diameter in the pregnant group increased from 13.6 cm ± 0.93 cm in the supine dorsal to 14.5 cm ± 0.83 cm (P.0001) in the kneeling squat position; in the nonpregnant women the increase was from 12.6 cm ± 0.92 cm to 13.5 cm ± 0.88 cm (P.0001).A kneeling squat position significantly increases the bony transverse and anteroposterior dimension in the mid pelvic plane and the pelvic outlet. Because this indicates that pelvic diameters change when women change positions, the potential for facilitation of delivery of the fetal head suggests further research that will compare maternal delivery positions is warranted.

Requisite to routine casework involving unidentified skeletal remains is the formulation of an accurate biological profile, including sex estimation. Choice of method(s) is invariably related to preservation and by association, available bones. It is vital that the method applied affords statistical quantification of accuracy rates and predictive confidence so that evidentiary requirements for legal submission are satisfied. Achieving the latter necessitates the application of contemporary population-specific standards. This study examines skeletal pelvic dimorphism in contemporary Western Australian individuals to quantify the accuracy of using pelvic measurements to estimate sex and to formulate a series of morphometric standards. The sample comprises pelvic multi-slice computer tomography (MSCT) scans from 200 male and 200 female adults. Following 3D rendering, the 3D coordinates of 24 landmarks are acquired using OsiriX® (v.4.1.1) with 12 inter-landmark linear measurements and two angles acquired using MorphDb. Measurements are analysed using basic descriptive statistics and discriminant functions analyses employing jackknife validation of classification results. All except two linear measurements are dimorphic with sex differences explaining up to 65 % of sample variance. Transverse pelvic outlet and subpubic angle contribute most significantly to sex discrimination with accuracy rates between 100 % (complete pelvis—10 variables) and 81.2 % (ischial length). This study represents the initial forensic research into pelvic sexual dimorphism in a Western Australian population. Given these methods, we conclude that this highly dimorphic bone can be used to classify sex with a high degree of expected accuracy.

We investigated the three-dimensional morphological characteristics of the pelvis in adult female patients with developmental dysplasia of the hip (DDH), using computerized tomography (CT) images. Forty-two subjects with normal hips and 40 DDH patients were recruited for the study. In the DDH group, the average transverse diameter of the pelvic inlet was significantly less and the average transverse diameter of the pelvic outlet was significantly greater than the measurements in the normal group. Further, the bony birth canal in DDH patients exhibited a higher incidence of anthropoid-type geometry, as defined by a longer sagittal diameter relative to the transverse diameter of the pelvic inlet. These findings indicate a characteristic pelvic geometry and suggest different development of the pelvis in the transverse direction in DDH patients. In addition, the obstetric conjugate length/transverse diameter of the pelvic inlet ratio was correlated to the degree of severity of acetabular dysplasia. This finding suggests that DDH is a manifestation of a developmental characteristic of the pelvis.

The projection point of the axis of the anterior column of the acetabulum on the outer table of the iliac wing was determined in 15 adult bony hemipelves. The optimal entry point for lag screw fixation in the anterior column was located 16 +/- 3.9 mm superior to the midpoint of the line connecting the apex of the sciatic notch with the notch between anterior superior iliac spine and anterior inferior iliac spine, and 46 +/- 5.9 mm superior to the acetabular rim. The mean inclination of the projected axis was 90.6 degrees +/- 5.0 degrees in the sagittal plane and 29.0 degrees +/- 4.4 degrees in the transverse plane. These data may facilitate insertion of a lag screw into the anterior acetabular column and minimize the risk of articular violation or cortical penetration because there is a narrow margin of safety. The lag screw placement also may be aided by palpating the anterior column with a finger and by intraoperative fluoroscopy for visualization of the hip joint and the anterior column in the obturator or pelvic outlet views.

INTRODUCTION AND HYPOTHESIS: The aim was to test the hypothesis that the pelvic outlet diameter (POD) is associated with pelvic organ prolapse (POP) in squirrel monkeys. METHODS: Magnetic resonance images (MRI) were obtained from 55 females with and without POP. Commercial software was used by two observers to measure the POD. POD, age, parity, and weight for the two groups were compared using Student’s t test. Associations of age, parity, and body weight with POD were evaluated with linear regression analysis. Multiple regression analysis examined the relationships of age, parity, and POD with POP. Receiver operating curve methods were used to set thresholds. RESULTS: Observers concurred on measurements (Cronbach’s alpha=0.96 with lower 95 % confidence limit of 0.94). POD was not related to parity (p=0.10) or weight (p=0.053), but was inversely related to age (p=0.011). Animals with POP did not differ from those without POP with regard to age (p=0.10), weight (p=0.17), or POD (p=0.99). The groups differed with regard to parity (p=0.007) and multiple regression methods demonstrated that only parity had a significant relationship with POP (p=0.002). Parity greater than 2 had 64 % specificity and 89 % sensitivity for POP. CONCLUSIONS: POD size does not contribute to POP in squirrel monkeys. This study confirms that among variables of age, body weight, POD, and parity, only parity appears as a risk factor for POP in squirrel monkeys.

URSM (Urorectal Septum Malformation Sequence) in humans is a well-known specific developmental abnormalities originally described in about 25 years ago including the absence of anal, urethral and vaginal openings, ambiguous genitalia and genito-urinary anomalies 1. Before the introduced the term in human medicine, authors used the terms including ‘female pseudohermaphroditism with anorectal malformation, hypoplastic pelvic outlet and persistent cloaca’ 2. The extent of variation in human URSM cases is from complete to partial or milder variant forms characterized by a single openining draining the cloaca might be compatible with life 3.

The study reports a reconstruction of the sacrum in STS 14 based on extrapolation from the measurements of the first two sacral vertebrae of STS 14 and of the angle formed by the anterior surfaces of their vertebral bodies. Reconstruction is based on comparisons of, and extrapolation from, sacra of Pan troglodytes, Homo sapiens, and Australopithecus afarensis. The reconstructed sacrum has an anterior sacral curvature of 39°. The two ossa coxae were also completed by mirror imaging of one side by the other. With the pelvis completely reconstructed, the pelvic dimensions for the antero-posterior (AP) diameters of the pelvic inlet, midpelvis, and pelvic outlet are 85, 68, and 69 mm and the corresponding transverse (TR) diameters are 109, 88, and 103 mm, respectively. The posterior sagittal diameters in the three pelvic planes are small compared to the anterior sagittal diameters. This analysis indicates that the STS 14 pelvis is platypelloid in the three pelvic planes; i.e., all the AP diameters are smaller than the corresponding TR diameters. This makes the STS 14 pelvis similar to that to Al 288-1, save for a less pronounced degree of platypelloidy at the inlet in the former. © 1995 Wiley-Liss, Inc.

To investigate correlation between key diameters of pelvic inlet and outlet planes and female pelvic floor dysfunction (FPFD).Correlation with incidence of FPFD was analyzed by measuring the two diameters of pelvic inlet and outlet planes (i.e. anteroposterior diameter of pelvic inlet and transverse diameter of pelvic outlet) in 298 patients with FPFD and 508 patients in control group taking into account of other relevant factors.The transverse diameter of pelvic outlet was significantly larger in experimental group than in control group (9.55cm vs. 8.50cm, P0.01); while the difference in anteroposterior diameter of pelvic inlet between the two groups was not statistically significant (11.63cm vs. 11.26cm, P=0.2050.01); Binary logistic regression analysis indicated that the anteroposterior diameter of pelvic inlet was not correlated with incidence of FPFD, but the transverse diameter of pelvic outlet was one of the influencing factor for FPFD.The transverse diameter of pelvic outlet is closely correlated with incidence of FPFD and represents one of the risk factors for FPFD; a transverse diameter of pelvic outlet greater than 9.5cm is the threshold for onset of FPFD and can be used as an early predictive index for FPFD.

The pathogenesis of otitis media is multifactorial, but the role of evolution on its development has not been addressed. We posit that the high prevalence of middle-ear disease is most likely restricted to humans, in contrast to other wild species, because the associated hearing loss would have reduced the fitness of affected individuals as a result of predation. We present here the possible consequences of two human adaptations that may have resulted in ubiquitous otitis media: the interaction of bipedalism and increased brain size, and the loss of facial prognathism resulting from speech or cooking. As a consequence of our adaptation for bipedalism, the female pelvic outlet is constricted, which, in the context of a rapidly enlarging brain, results in humans being born 12 months too soon. Significantly, immature eustachian tube structure and function, in conjunction with an immature immune system, helps to explain the high incidence of otitis media in the first year of life. But the persistence of middle-ear disease beyond this stage is not explained by "immaturity." The morphology of the palate changed with the adaptations that produced facial flattening, with concomitant effects on eustachian tube function. These changes resulted in relatively poor human physiologic tubal function in comparison to the nonhuman primate.

OBJECTIVE. The purpose of this article is to present the route of extension in nine soft-tissue tumors and tumorlike lesions of the pelvic wall.CONCLUSION. Soft-tissue tumors of the pelvis, particularly malignant ones, extend into other compartments through specific pathways that are bordered by bones, ligaments, and fasciae. Such pathways include the greater sciatic foramen, the obturator foramen, the femoral canal, the muscular lacuna, the pelvic outlet, and the inguinal canal.

The manner of innervation of the pelvic outlet muscles in fowl (Gallus gallus domesticus) was examined in detail in four male pelvic halves. The segmental arrangement of the nerve supply in the sacral and pudendal plexuses was compared to that of Lacertilia and Urodela as a basis for a morphologiccal analysis of the pelvic outlet muscles. From the viewpoint of innervation, the pelvic outlet muscles of fowl are classified into two groups: a sphincter muscle group and a levator muscle group. These two groups are closely related to the ventral muscles of the pelvic limb. In contrast to the morphology of pelvic outlet muscles in lacertilians, in fowl the caudal muscle element does not contribute to the formation of these muscles. © 1992 Wiley-Liss, Inc.

Four pelvic halves from two Japanese giant salamanders (Cryptobranchidae Megalobatrachus japonicus, one male and one female) were dissected in order to obtain detailed morphological data on the lumbosacral plexus and the muscles of the pelvic outlet. According to the positions of the passage of the metazonal nerves, the nerves can be divided into three groups: 1) the nerves passing dorsal to the caudofemoralis muscle, 2) the nerves passing between the caudofemoralis and the caudoischiadicus, 3) the nerves passing ventral to the caudoischiadicus. In consideration of the sites of origin from the lumbosacral plexus, a three-way stratificational analysis can be made, group 1 arising craniodorsal to group 2, and group 3 caudoventral to group 2. It is suggested that the three pelvic outlet muscles, the caudofemoralis, caudocruralis, and caudoischiadicus, have derived from the ventral muscles of the posterior limb, and have extended ventrocaudalwards.

Five pelvic halves from three male iguanas (Iguanidae Iguana iguana) and two pelvic halves from one male varanus (Varanidae Varanus (dumerillii)), were dissected in order to obtain detailed data on the relationship of the lumbosacral plexus and the muscles of the pelvic outlet. According to the positions of the passage of the metazonal nerves, the nerves can be divided into three groups: 1) the nerves passing dorsal to the caudofemoralis muscle, 2) the nerves passing between the caudofemoralis and the caudoischiadicus major, 3) the nerves passing ventral to the caudoischiadicus major. In consideration of the sites of origin from the lumbosacral plexus, a stratificational analysis can be proposed; group 1 arises craniodorsal to group 2, and group 3 caudoventral to group 2. It is suggested that the pelvic outlet muscles (caudofemoralis, quadratus caudae, obliquus cloacae, transversus cloacae profundus, retractor penis, caudoischiadicus major, and the caudoischiadicus minor) are derived from the ventral muscles of the posterior limb, and have moved caudally concomitant with the caudal migration of the cloaca.

PLEASE NOTE THAT A MORE RECENT EDITION OF THIS TITLE IS AVAILABLE IN THE LIBRARYThe perineum is made up of the structures which make up the boundary of the pelvic outlet. It extends externally from the dorsal aspect of the scrotum or vulva to the base of the tail; its lateral margins extend to the skin covering the tubers ischii and superficial gluteal muscles. The deep portion is delineated by the ischial arch ventrally, the third coccygeal vertebra dorsally and, in the dog, by the sacrotuberous ligament laterally. Due to the absence of sacrotuberous ligament in the cat the lateral margins are less well defined. The perineum essentially surround the anal and urogenital canals. Within the perineum the most important structures are those which make up the pelvic diaphragm; namely levator ani and coccygeal muscles. This chapter looks at Anatomy and physiology; Diagnostic approach; and Clinical disorders of the perineum and anus.

The muscle changes related to pelvic floor disorders are poorly understood. We conducted an anatomical and histological study of the perineum of the normal mouse and of a transgenic mouse strain deficient in urokinase-type plasminogen activator (uPA−/−) that was previously reported to develop a high incidence of rectal prolapse. We could clearly identify the iliococcygeus (ILC) and pubococcygeus (PC) muscles and anal (SPA) and urethral (SPU) sphincters in male and female mice. The bulbocavernosus (BC), ischiocavernosus (ISC) and levator ani (LA) muscles could be found only in male mice. Histochemical analysis of the pelvic floor muscles revealed a majority of type IIA fibres. Rectal prolapses were observed only in male uPA−/− mice. The most obvious finding was an irreducible evagination of the rectal mucosa and a swelling of the entire perineal region corresponding to an irreducible hernia of the seminal vesicles through the pelvic outlet. The hernia caused stretching and thinning of the ISC, BC and LA. Myopathic damage, with degenerated and centronucleated myofibres, were observed in these muscles. The PC, ILC, SPA and SPU were not affected. This study provides an original description of a model of pelvic floor disorder and illustrates the differences existing between the perineum of humans and that of a quadruped species. In spite of these differences, the histopathologic changes observed in the pelvic floor muscles of uPA−/− mice with rectal prolapse suggest that prolonged muscular stretching causes a primary myopathic injury. This should be taken into account in the evaluation of pelvic floor disorders.

Malpositioning of iliosacral screws happens more often when common variations in the morphology of the upper sacral segments are unrecognized. Radiological-anatomic correlations of sacral anatomy were studied in 10 fresh-frozen cadaveric pelvises without evidence of skeletal disease, obtained from six male and four female donors. Eighty consecutive patients with complicated pelvic fractures treated operatively by the same surgeon using percutaneously placed iliosacral screws were evaluated. Variations in the sacral alar anatomy and slope found in upper sacral segmentation anomalies are common. Surgically important and predictable abnormal morphological patterns can be easily identified using pelvic outlet and lateral sacral plain radiographs along with computed tomographic scans. On the true lateral projections, the iliac cortical density adjacent to the sacroiliac joint parallels the sacral alar slope and is almost always caudal and posterior to it; it delineates the anterior extent of the "safe zone" for iliosacral screw insertion. Thus, the lateral sacral image provides the surgeon with a better understanding of the sacral alar slope and can help prevent iliosacral screw placement errors. The lateral sacral image should always be used intraoperatively with the inlet and outlet images to guide iliosacral screw placement.

A complex of traits in the femur and pelvis of Homo ereclus and early “erectus-like” specimens has been described, but never satisfactorily explained. Here the functional relationships between pelvic and femoral structure in humans are explored using both theoretical biomechanical models and empirical tests within modern samples of diverse body form (Pecos Amerindians, East Africans). Results indicate that a long femoral neck increases mediolateral bending of the femoral diaphysis and decreases gluteal abductor and hip joint reaction forces. Increasing biacetabular breadth along with femoral neck length further increases M-L bending of the femoral shaft and maintains abductor and joint reaction forces at near “normal” levels. When compared to modern humans, Homo erectus and early “erectus-like” specimens are characterized by a long femoral neck and greatly increased M-L relative to A-P bending strength of the femoral shaft, coupled with no decrease in hip joint size and a probable increase in abductor force relative to body size. All of this strongly suggests that biacetabular breadth as well as femoral neck length was relatively large in early Homo. Several features preserved in early Homo partial hip bones also indicate that the true (lower) pelvis was very M-L broad, as well as A-P narrow. This is similar to the lower pelvic shape of australopithecines and suggests that nonrotational birth, in which the newborn's head is oriented transversely through the pelvic outlet, characterized early Homo as well as Australopithecus. Because M-L breadth of the pelvis is constrained by other factors, this may have limited increases in cranial capacity within Homo until rotational birth was established during the late Middle Pleistocene. During or after the transition to rotational birth biacetabular breadth decreased, reducing the body weight moment arm about the hip and allowing femoral neck length (abductor moment arm) to also decrease, both of which reduced M-L bending of the proximal femoral shaft. Variation in femoral structural properties within early Homo and other East African Early Pleistocene specimens has several taxonomic and phylogenetic implications. © 1995 Wiley-Liss, Inc.

Background: The Manner of innervation of the muscles of the inferior limb, pelvic outlet, and tail in rhesus monkey (Macaca maulatta) was investigated in detail in 11 pelvic halves of lour males and two females. Results: The origins of the pudendal nerve were widespread and overlapped the sacral plexus. After removal of the bone structures, detailed dissection revealed the origin of the pudendal nerve to ventrocaudally overlap the sacral plexus. This dorsoventral branching pattern between the sacral plexus and the pudendal nerve is similar to that in Urodela (akita, 1992b) Lacertilia (Akita, 1992a) and AVes (Akita et al., 1992a), and is a basis for morphological understanding of the muscles of the pelvic outlet. Conclusion: The muscles of the pelvic outlet consist of the leavtor, sphincter, and tail muscle groups, based on the stratification of the supplying nerves the former two groups likely dervice from the ventral muscles of the inferior limb, and the latter group from the ventral caudal (trunk) muscles. © 1995 Wiley-Liss, Inc.

The aim of this study was a statistics-based exploration of a typology of the female pelvis. The research sample included 172 females aged from 18 to 69. For measurements, the three dimensional CT images of pelvis were used. A cluster analysis was performed on anteroposterion and transverse diameters of the pelvic inlet and the midplane. The results revealed three clusters representing gynecoid, “narrow”, and intermediate types of female pelvis. The distribution of pelvic types in age groups indicates a tendency for the “narrow” pelvis to be presented more frequently in the group of younger females. Variability and typology of the female pelvis is a traditional topic in anthropological studies [3, 4, 13, 17]. The best known classification of the female pelvis was suggested by Caldwell and Moloy in 1933 [3] and it was based on the pelvic inlet shape. In the frame of this classification, four main pelvic types were suggested: gynecoid, android, anthropoid, and platypelloid. The development of this classification resulted in the identification of the mixed types and subtypes based on the width of the pelvic outlet [3]. As a result, more than twenty subtypes were suggested that complicated their analytical implication. In addition, the critics of this classification addressed the subjective impression in the judgments of pelvic shapes without a well established statistical base [19]. A tendency of increase in cesarean section is observed in the last decades [2,5, 9, 15]. In Latvia, the number of cesarean section delivery is growing from 3.9% in 1980 to 23.7% in 2010 [18]. A narrow pelvis is one of the factors increasing the risk for cesarean section [12]. On the one hand, there is a solution for the narrow pelvis problem from the obstetric perspective. On the other hand, a more detailed analysis is needed from the anthropological perspective because of possible evolutionary trends in the human body in general and in the pelvic shape in particular. The aim of this study was a statistics-based exploration of a typology of the female pelvis. A well recognized anthropological tendency of the last century is the secular trend in growth. Previous studies demonstrate an increase in the mean height about 1–2 cm per decade in different European countries [6, 8]. An investigation of external body parameters of Latvian women also demonstrated significant changes in the period of 70 years. The women’s height increased for 6 cm, shoulder breadth increased for 0.6 cm, and the hip breadth increased for 2.9 cm [8]. Based on the relationship between the lesser pelvic parameters and height observed in previous studies [7, 11, 13], it is possible to expect that parameters of the lesser pelvis also changed during the last 6–7 decades. It should be noted that the female pelvic cavity has a cylindrical shape with the narrowest place in the midplane between two ischial spines (the bispinous diameter). The obstetric importance of the pelvic inlet and the midplane was emphasized in anthropological studies [3, 4, 16, 17]. In a typical female pelvis, a longer diameter of the inlet (the transverse diameter) and a longer diameter ofthe midplane (the anteroposterior diameter) are placed perpendicularly. Therefore, a fetal head rotates from a transverse position in the pelvic inlet to a sagittal position in the midplane. A narrowing of the pelvic cavity in the midplane causes this rotation. Stalberg at al. [12] demonstrated that a narrow pelvic midplane is an important reason for the emergency cesarean section. In addition, an inadequate proportion of the pelvic inlet also causes cesarean section [1]. Therefore, both the pelvic inlet and the midplane are highly important from the anthropological perspective and need to be included in a statistics-based exploration of the female pelvic typology. Changing body parameters allow to expect age differences in a distribution of pelvic types between younger and older females. As a result, two research questions were posed for the presentstudy: 1. What female pelvic types could be detected on the basis of the measures of the inlet and the midplane of the lesser pelvis? 2. How does the distribution of female pelvic types among age groups differ?

The perineum is defined as the region of body below the pelvic diaphragm that lies within the boundaries of the pelvic outlet. It is the region which is home to pathologic conditions which include primary tumors, neoplasms of adjacent organs with sec-ondary invo l vement, congenital or acquired cystic lesions and inflammatory lesions. In this article, we describe CT and MR imaging anatomy and various pathologic processes that affect this anatomic region, with a brief discussion. Emphasis is give n to imaging features that help to characterize specific lesions.

Anatomic and radiographic studies were performed on three cadaveric pelves to define recommendations for better anterior pelvic external fixator pin placement. A thick zone of bone was identified for pin purchase beginning along the iliac crest 2-3 cm posterior to the anterior superior iliac spine (ASIS), and extending 6-8 cm posteriorly along the crest. This zone is hourglass-shaped, and follows the superior gluteal ridge to the superior acetabular region. This zone has a maximal thickness of 4 cm in the supra-acetabular region, and a minimum of 8 mm at the isthmus. Cortical pin penetration is more likely to occur if pin placement begins in the lateral third of the iliac crest, or if the pin is advanced beyond the isthmus of this zone, 5 cm from the crest. Acetabular penetration occurs when the pins are advanced farther than 10.5 cm. Radiographic evaluation demonstrates that only the pelvic outlet view gives the proper orientation of the iliac tables to guide the angle of the pin placement (24 degrees from vertical) and to confirm proper pin placement. Computed tomography (CT) evaluation with "inlet" positioning of the gantry gives complementary information for pin placement.

The pelvic cavities two australopithecines (Al 288, Sts 14) are studied biometrically in relation to a sample of extant human and non-human primates. Human obstetrical characteristics correspond to (1) a generic adaptation of the pelvic outlet which is opened ventrally to the ischial tuberosities, and (2) a sexual adaptation of the female inlet which is particularly enlarged between the hip joints and the pubic rami. The australopithecine pelvis presents most of these characteristics, but offers some significant dissimilarities notably an extreme biacetabular enlargement and a very specific morphology of the pubic region. A series of deductions leads us to suggest a Homo-like obstetrical mechanism for Australopithecus, characterized by the rotation and the flexion of the neonate, with fetal skull size similar to the one of the neonate chimpanzee, in the pelvic cavity. The constraints on the fetal skull are consequently as important as in human delivery. This means that the phenomenon of encephalization which took place during the evolution of the hominids could not be the result of an increase of the neonate cerebral capacity but was rather a consequence of neotenic change in growth-rhythm of the newborn.

Summary The levator ani is, contrary to earlier descriptions, interwoven at its insertion with the external anal sphincter and constrictor vestibuli muscles forming a complex morphological unit. Most fibres of the anal sphincter decussate in the perineal body but a contingent from the lateral border of the muscle descends directly into the ipsilateral constrictor vestibuli. The more superficial fibres of the greater (decussated) part continue into the contralateral constrictor vulvae whilst the deeper fibres join the contralateral constrictor vestibuli. The motor nerve supply to the perineal muscles was established by electrical stimulation of the sacral nerves and electromyographical recording of the evoked potentials. The cloacal sphincter derivatives are innervated by the pudendal nerve but the coccygeus and levator are muscles are innervated by rami musculares (from S4 and sometimes S5) and not from pudendal branches as reported for the cow and horse. The levator ani and coccygeus muscles develop together. Both initially arise from the pelvic symphysis without connexion with the primordia of the anal and urogenital sphincters. Their insertions shift secondarily to the pelvic spine and coccygeal vertebrae and, where the levator ani is concerned, to the perineal sphincters. Zusammenfassung Die Anatomie und Embryologie des Beckenausganges der weiblichen Ziege Entgegen fruheren Angaben ist der M. levator ani an seiner Insertion mit den Mm. sphincter ani ext. und constrictor vestibuli durchwebt, so das hier eine komplexe morphologische Einheit besteht. Die meisten Muskelfasern des M. sphincter ani kreuzen in den Dammkorper hinein; ein Anteil des lateralen Randes des Muskels begibt sich jedoch direkt zwischen die Fasern des gleichseitigen M. constrictor vestibuli. Die mehr oberflachlich gelegenen Fasern des groseren, gekreuzten Teiles setzen sich in den andersseitigen M. constrictor vulvae fort, wahrend die tieferen Fasern sich mit dem andersseitigen M. constrictor vestibuli vereinen. Die motorische Innervation der Damm-Muskeln wurde durch Elektrostimulation der Kreuznerven und elektromyographische Aufzeichnung der entstandenen Potentiale gewonnen. Die Abkommlinge des M. sphincter cloacae werden vom N. pudendus versorgt, die Mm. coccygeus und levator ani durch Muskelaste (von S4, zuweilen S5) und nicht durch Rami pudendi, wie fur Rind und Pferd angegeben. Die letzten beiden Muskeln entwickeln sich gemeinsam. Beide kommen ursprunglich von der Symphysis pelvis, und zwar ohne Verbindung mit den analen und urogenitalen Sphinkteren. Ihre Insertion erreicht sekundar die Spina ischiadica und das Kreuzbein sowie, mit Beteiligung des M. levator ani, die perinealen Sphinkteren. Resume Anatomie et embryologie de la region perineale chez la Chevre Contrariement aux descriptions anterieures, le releveur de l'anus mele ses insertions aux muscles sphincter externe de l'anus et constricteur vestibulaire en formant avec eux un ensemble morphologique complexe. Beaucoup de fibres du sphincter anal s'entrecroisent dans le centre fibreux du perinee mais un contingent descend directement du bord lateral du muscle dans le constricteur vestibulaire ipsilateral. La plupart des fibres superficielles de la partie principale, entrecroisee, se continuent dans le constricteur contralateral de la vulve, tandis que les fibres plus profondes rejoignent le constricteur contralateral du vestibule. La distribution des nerfs moteurs dans les muscles du perinee a eteetudiee par stimulation electrique des nerfs sacraux et par enregistrement electromyographique des potentiels evoques. Les derives du sphincter cloacal sont innerves par le nerf honteux mais le coccygien et le releveur de l'anus le sont par des rameaux musculaires de S4 et quelquefois S 5 et non par des branches du nerf honteux, comme cela est decrit chez la Vache et la Jument. Les muscles releveur de l'anus et coccygeus se developpent ensemble. Tous deux prennent origine sur la symphyse pelvienne, sans relation avec les ebauches des sphincters anal et uro-genital. Leurs insertions se reportent secondairement au sacrum et aux vertebres coccygiennes et en ce qui concerne le releveur de l'anus, au sphincter du perinee. Resumen La anatomia de la apertura inferior de la pelvis en la cabra En desacuerdo con opiniones anteriores, el M. levator ani se entreteje con los Mm. sphincter ani ext. y constrictor vestibuli en su insercion, de manera que se forma una unidad morfologica muy compleja. La mayoria de las fibras musculares del M. sphincter analis cruzan hacia el cuerpo del perine; una parte del borde lateral del musculo va directamente a entremezclarse con las fibras del M. constrictor vestibuli del mismo lado. Las fibras superficiales de la porcion mayor, cruzada, se continuan con el M. constrictor vulvae del otro lado; al mismo tiempo, las fibras profundas se unen al M. constrictor vestibule del otro lado. La inervacion motora de los musculos del perine se estudio mediante la estimulacion electrica de los nervios sacros y la anotacion electromiografica de los potenciales asi producidos. Los derivados del M. sphincter cloacae reciben su inervacion del N. pudendo, los Mm. coccygeus y levator ani estan inervados por ramas musculares (de S4 y a veces S5) y no por ramas pudendas como se anota para las reses y los caballos. Los ultimos dos musculos mencionados se desarrollan conjuntamente. Ambos provienen originalmente de la Symphysis pelvis sin relacion con los musculos esfinteres anales o urogenitales. Su insercion llega secundariamente a la Spina ischiadica y al sacro, asi como, mediante la contribucion del M. levator ani, a los esfinteres perineales.

Vaginal sound, with transmitter crystals of 2 MHz, is used when measuring the interspinous diameter. The echo from pelvic wall, the effect on the measured spinal diameter by altering the position of the ultrasonic transmitter, and the influence of air or faeces between the ultrasound transmitter and the pelvic wall, have been analysed in a series of model trials on a dummy submerged in water. Thereafter clinical trials were performed on 102 women, pregnant in their 9th month. The results obtained when measuring the interspinous diameter on the ultrasonic tomogram were compared with the results obtained when measuring the same distance on a frontal x-ray picture taken using the orthographic technique according to Borell-Frenström. The method is suitable for selecting those cases with suspect constriction of the pelvic outlet for an x-ray examination by the Borell-Fernström technique.

The morphology and its variation of the bony pelvis in British species of Muridae and Cricetidae have been studied. The investigation began with the application of a mensural method for demonstrating sexual dimorphism and it is shown that for all species except those of Rattus the male os coxa can be distinguished from the female over a wide range of ages. During the study it became obvious that there are ranges of morphological variation in os coxae both inter- and intraspecific. There are constant interpecific differences which allow identification of os coxae of these rodents at least to genus and in many cases to species. Detailed descriptions of the morphology of the os coxa of each species are given together with an identification key. Intraspecific variation is mainly sex-dependent and comprises sexual dimorphism, male pubertal changes and female parturition changes. The changes in the male are from epicene, through pubertal, to post-pubertal phase, with the first of these resembling the agonadal, female, form and the last with a posterior border thickened and tuberculate in relation to the hypertrophied penis and its associated glands and musculature. These phases are not equally obvious in all species, but the pelvis in all except Rattus and Mus shows some evidence of the sexual development of the animal. In females the form of the pelvis may be modified during successive pregnancies to allow a wider pelvic outlet for parturition. Resorption and remoulding of the female pelvis allows the recognition of non-parous, uniparous and multiparous animals in all Cricetid species, in Micromys and, more doubtfully, in Mus, but not in Apodemus and Rattus. Non-sex-dependent intraspecific variation, comprising differences in rugosity related to muscularity is also described. The observations are discussed in relation to earlier experimental work, to the need for basic research on small mammal reproduction and population structure, and to the use of the pelvis in the analysis of osteological assemblages, such as occur in owl pellets.

Two newborn male infants are reported in whom a contracted pelvic outlet was found to be associated with a very small bladder and urethra and absent kidneys.It is suggested that this roentgen finding in the bony pelvis of a newborn may represent another possible clue as to the likelihood of a coexisting severe malformation (underdevelopment) of the urinary tract.

A method of pelvimetry is described which is recommended for standardisation. Two radiographic views are required, three if the pelvic outlet is to be measured. Only two measurements are recorded by the radiographer. No calculations are necessary. Procedure.—Metal calipers are applied to the pelvis in the manner suggested by Hederman (1940): (a) At the level of the pelvic brim in Thoms' position (a special manoeuvre ensures that the obstetric conjugate is horizontal). (b) In the sagittal plane. The anode-film distance is not critical. The caliper measurement is recorded in each instance. The “pelvimetry protractor” is constructed from a rectangular sheet of perspex. It bears a centimetre scale from each division of which lines are engraved which radiate uniformly. A cursor thread with sliding hooks may be moved up and down parallel to the scale. Mode of use.—Two radiating lines are chosen according to the recorded caliper measurement by reference to the basal centimetre scale. The protractor is placed ove...

A small bony pelvic outlet had previously been noted in newborns with lethal respiratory problems who had absent or nonfunctioning kidneys and bladder hypoplasia. The suggestion was made that the small pelvic bony outlet reflected the bladder development, and that these roentgenographic findings were a clue to renal agenesis in newborns with respiratory distress. All the patients also had imperforate anus with rectovesical fistula and segmental sacral agenesis.Three patients are reported, all of whom had small bladders. In 2 there were renal agenesis and bladder hypoplasia, but the bony pelvis was normal. In the third case, bladder hypoplasia and a small pelvic outlet were present; the patient had segmental sacral agenesis with normal kidneys and has survived.Review of all prior cases of small bony pelvic outlet reveals the common denominator to be neuromuscular deficit accompanying segmental sacral agenesis rather than renal agenesis or bladder hypoplasia, When imperforate anus with sacral and urologic a...

The anatomy of parts of the pelvic outlet and perineum is described in an adult male gorilla. Two previously undescribed muscles are presented: (1) The puborectalis muscle, completely separated from the levator ani, arises from the region of the symphysis and forms a sling for the rectum while it also substitutes for the perineal membrane. (2) The puboampullaris muscle, a paired smooth muscle, arises from the pubis and inserts into the rectum to elevate the rectum while additionally providing support for the urogenital viscera. The levator ani muscle is recounted to point out its lack of attachment to the pelvic viscera while allowing a hiatus in which the rectum is exposed within the perineum. The sphincter urethrae muscle is presented emphasizing its true sphincteric characteristics, its absence of lateral attachments and its similarity to man. Other muscles of the pelvis and perineum as well as urogenital viscera are described or modified where necessary. The manner in which these structures enter into the support of the pelvic viscera is considered.

A contracted pelvis is one in which either the shape or size is sufficiently abnormal to cause difficulty in the delivery of a normal-sized fetus. Disproportion is a term which embraces a wider group and indicates any disparity in size between the fetus and pelvis that will lead to difficulties in labour, or dystocia. Thus, even when the patient has a normal pelvis, disproportion will exist if the fetus presents by the brow, has hydrocephalus or is excessively large. A badly flexed occipito-posterior position may also cause disproportion.

A method is described for measuring the pelvic dimensions of the ewe from one lateral and one ventro-dorsal radiograph. Estimates of the conjugate and transverse diameters of the pelvic inlet, and the distance separating the lateral ischial tuberosities, accurate to within 5% of post-mortem measurements, were obtained from 11 sheep by employing a large target-film distance and applying correction factors for each of the planes of interest. Estimates of the distance between the posterior promontories of the ischium agreed less well with post-mortem measurements, but this may be related to the difficulty in locating this point accurately at post mortem. The pelvic outlet was estimated poorly by radiographic pelvimetry (r = 0.68) and was considered to be of little value in predicting the size of the pelvic outlet at parturition.

The perineum forms the floor of the pelvis and, as the pelvic outlet, represents the perineal approach to the rectum. The perineal region extends from the inferior border of the pubic symphysis to the tip of the coccyx, and laterally to the inferior ramus of the pubis and the ischial tuberosity. The sacrotuberous ligaments complete the outline. The perineal region is diamond shaped and can be divided by a transverse line into an anterior triangle, the urogenital region, and a posterior triangle, the anal region. The line separating these two regions runs just behind the bulb of the urethra, or in the female behind the vagina. The line corresponds to the transverse septum of the perineal muscles (linea septi perinei). The midpoint of this line is the central point of the region (central point of the perineum). In the upright position and when sitting or lying with adducted legs the perineal region is hidden. Abduction of the legs brings the perineal region into view. For muscles and fasciae see Fig. 33, lymphatics Fig. 79. Anal region p. 268, urogenital region p. 270, central tendon of perineum p. 271.