Surgical anatomy of the perineal muscles and their role in perineal disorders

The anterior perineum contains the perineal body and muscles. It is the site of functional and pathological disorders, many of which have not yet been related to a precise cause. In the present study, we investigated the anatomy of the perineal muscles with the aim of elucidating their function in light of their anatomic structure. Knowledge of their functional-structural relationship is deemed necessary for the understanding of the disorders that affect this part of the perineum. The perineal muscles of 28 cadaveric specimens were studied by direct dissection, as well as histologically. Fifteen male and 13 female specimens were collected from 18 adult (mean (+/- SD) age 31.6 +/- 9.8 years) and 10 neonate cadavers. Histological sections were stained with hematoxylin and eosin and Masson's trichrome stain. The fibers of the superficial transverse perineal muscle proceeded medially to decussate in a criss-cross pattern with the muscle fibers of the contralateral muscle; a few muscle fibers passed directly without decussation. Similarly, the fibers of the deep transverse perineal muscle decussated with their fellows on the opposite side. The two decussation raphes constituted the main bulk of the perineal body. A 'digastric' pattern could be identified for each of the superficial transverse perineal muscle and deep transverse perineal muscle. This pattern allows simultaneous contraction of the muscles on both sides as a single unit. The perineal muscles, forming the floor of the anterior perineum, are apparently subjected to variations in intra-abdominal pressure, which, if exceeding normal physiological limits, may lead to weakening, subluxation and sagging of the perineal muscles and, eventually, to perineocele. Further studies to investigate the role of the perineal muscles in the functional disorders of the perineum are needed.     

Anatomy and physiology of the female perineal body with relevance to obstetrical injury and repair

The female perineal body is a mass of interlocking muscular, fascial, and fibrous components lying between the vagina and anorectum. The perineal body is also an integral attachment point for components of the urinary and fecal continence mechanisms, which are commonly damaged during vaginal childbirth. Repair of injuries to the perineal body caused by spontaneous tears or episiotomy are topics too often neglected in medical education. This review presents the anatomy and physiology of the female perineal body, as well as clinical considerations for pelvic reconstructive surgery.     

Comparison of the contractile properties, oxidative capacities and fibre type profiles of the voluntary sphincters of continence in the rat

The external urethral sphincter (EUS) and external anal sphincter (EAS) are the principal voluntary striated muscles that sustain continence of urine and faeces. In light of their common embryological origin, shared tonic sphincteric action and synchronized electrical activity in vivo, it was expected that they would exhibit similar physiological and structural properties. However, the findings of this study using paired observations of both sphincters isolated from the rat show clearly that this is not the case. The anal sphincter is much more fatigable than the urethral sphincter. On completion of a fatigue protocol, the amplitude of the last twitch of the EAS had declined to 42 ± 3% of the first twitch, whereas the last twitch of the EUS was almost identical to that of the first (95 ± 3%). Immunocytochemical detection of myosin heavy‐chain isoforms showed that this difference was not due to the presence of more slow‐twitch oxidative type 1 fibres in the EUS compared with the EAS (areal densities 4 ± 1% and 5 ± 1%, respectively; P = 0.35). In addition, the fatigue difference was not explained by a greater contribution to force production by fast oxidative type 2A fibres in the urethral sphincter. In fact, the anal sphincter contained a higher areal density of type 2A fibres (56 ± 5% vs. 37 ± 4% in the EUS, P = 0.017). The higher oxidative capacity of the EUS, measured histochemically, explained its fatigue resistance. These results were surprising because the fatigue‐resistant urethral muscle exhibited faster single‐twitch contraction times compared with the anal sphincter (56 ± 0.87 ms vs. 72.5 ± 1.16 ms, P < 0.001). Neither sphincter expressed the type 2X myosin isoform but the fast‐twitch isoform type 2B was found exclusively in the EUS (areal density 16 ± 2%). The type 2B fibres of the EUS were small (diameter 19.5 ± 0.4 μm) in comparison to typical type 2B fibres of other muscles. As a whole the EUS is a more oxidative than glycolytic muscle. In conclusion, analysis of the twitch mechanics and fatigue of two sphincters showed that the EUS contained more fatigue‐resistant muscle fibres compared with the EAS.     

Interactive three-dimensional teaching models of the female and male pelvic floor

Controversies regarding structure and function of the pelvic floor persist because of its poor accessibility and complex anatomical architecture. Most data are based on dissection. This “surgical” approach requires profound prior knowledge, because applying the scalpel precludes a “second look.” The “sectional” approach does not entail these limitations, but requires segmentation of structures and three-dimensional reconstruction. This approach has produced several “Visible Human Projects.” We dealt with limited spatial resolution and difficult-to-segment structures by proceeding from clear-cut to more fuzzy boundaries and comparing segmentation between investigators. We observed that the bicipital levator ani muscle consisted of pubovisceral and puborectal portions; that the pubovisceral muscle formed, together with rectococcygeal and rectoperineal muscles, a rectal diaphragm; that the external anal sphincter consisted of its subcutaneous portion and the puborectal muscle only; that the striated urethral sphincter had three parts, of which the middle (urethral compressor) was best developed in females and the circular lower (“membranous”) best in males; that the rectourethral muscle, an anterior extension of the rectal longitudinal smooth muscle, developed a fibrous node in its center (perineal body); that the perineal body was much better developed in females than males, so that the rectourethral subdivision into posterior rectoperineal and anterior deep perineal muscles was more obvious in females; that the superficial transverse perineal muscle attached to the fibrous septa of the ischioanal fat; and that the uterosacral ligaments and mesorectal fascia colocalized. To facilitate comprehension of the modified topography we provide interactive 3D-PDFs that are freely available for teaching purposes. Clin. Anat. 33:275–285, 2020. © 2019 Wiley Periodicals, Inc.     

Perineal groove: A rare congenital abnormality of failure of fusion of the perineal raphe and discussion of its embryological origin

We present a case where a baby girl was born with failure of fusion of the perineal raphe. To our knowledge, there has been limited reports of this form of congenital abnormality in the literature and is referred to as “perineal groove.” The incidence of perineal groove is unclear but it is considered to be rare. This case reviews the embryological origin of this congenital abnormality. Clin. Anat. 22:823–825, 2009.© 2009 Wiley‐Liss, Inc.     

The developmental anatomy of the human superior hypogastric plexus: A morphometrical investigation with clinical and surgical correlations

The superior hypogastric plexus (SHP) is the part of the autonomic nervous system, which is responsible for the sympathetic innervation of pelvic organs and extrapelvic genitals in humans of both sexes. The SHP also functions as the anatomic pathway for the major part of visceral sensitive fibers originating from pelvic viscera. In this study, the morphology of the SHP was analyzed through anatomical dissections performed both in human adult and fetal cadavers. A computerized morphometrical investigation of the SHP was also performed and the resulting quantitative data statistically assessed. The comparison between fetal and adult SHP revealed that in the male group there was a developmental increase of six times (in height) and of about five times (in width); while in the female group, there was a developmental increase of 3.5 times both in height and width values. In addition, the distance from the superior border of the SHP to the bifurcation of the common iliac arteries presented a developmental increase of about six times in the male group, and about four times in the female group. We propose an original morphological classification with six types, based upon the anatomical arrangement of the nervous fibers in this autonomic plexus.     

Striated Perineal Muscles: Location of Autonomic,Sensory, and Somatic Neurons Projecting to the Male Pig Bulbospongiosus Muscle

The location, number, and size of the neurons innervating the bulbospongiosus muscle (BSM) were studied in male pigs, by means of Fast Blue (FB) retrograde transport. After injection of FB into the left BSM, labeled neurons were found bilaterally in the L2‐S4 sympathetic trunk ganglia (STGs), in the caudal mesenteric ganglia (CMGs), in the microganglia of the pelvic plexus (PGs), in a dorsolateral area with respect to the central canal of S1‐S3 segments of the spinal cord (SC) and in the S1‐S4 ipsilateral and S2‐S3 contralateral spinal ganglia (SGs). The mean number of labeled FB cells was 3,122 ± 1,968 in STGs, 979 ± 667 in CMGs, 108 ± 104 in PGs, 89 ± 39 in SC and 77 ± 23 in SGs. The area of the multipolar neurons was 852 ± 22 μm² in the STGs, 878 ± 23 μm² in the CMGs and 922 ± 31 μm² in the PGs. The multipolar SC neurons had an area of 1,057 ± 38 μm², while pseudounipolar SG cells had dimensions of 2,281 ± 129 μm². Our research enables us to highlight two peculiarities regarding the innervation of the boar BSM: the very high number of labeled autonomic neurons and the particular localization of the motor somatic nucleus. Anat Rec, 2009. © 2009 Wiley‐Liss, Inc.     

Development of multimedia learning modules for teaching human anatomy: application to osteology and functional anatomy

Computer-assisted learning (CAL) is growing quickly within academic programs. Although the anatomical commercial packages that are available for this learning have attractive advantages, they also have drawbacks: they are frequently not in the local language of the students, they do not perfectly answer the needs of the local academic program, and their cost is frequently more than students can afford. This study describes a relatively inexpensive method to create CAL tutorials, whose content can be fully customized to local academic needs in terms of both program and language. The study describes its use in creating multimedia learning modules (MLMs) about Osteology and joint kinematics. The pedagogical content in these modules was collected from objective experiments to give students the opportunity to access new scientific knowledge during their education. It can be replaced, as desired, by almost any content due to the flexibility of the production method. Each MLM consists of two complementary subelements: a multimedia theoretical lecture and a three-dimensional interactive laboratory. Such MLMs are in use at both the University of Brussels (ULB) and the National University of Rwanda (NUR). The development of this work was part of the VAKHUM project, and the pedagogical validation is currently being performed as part of the MULTIMOD project.     

Light and electron microscopy of the human hepato-duodenal ligament: A morpho functional study

The morpho-functional relationships between the hepato-duodenal ligament and the superior part of the duodenum are analysed. Twenty-four specimens were removed during necropsies of adults and prepared according to various mesoscopic, microscopic, and ultramicroscopical methods, i. e., whole-mounts, membrane preparations, thick and thin histological sections, and polarized light, scanning, and transmission electron microscopy were employed. The hepato-duodenal ligament is formed by longitudinally elongated, type I collagen fiber bundles which are interlinked by more delicate bundles of type III collagen fibers. Longitudinally disposed elastic fibers are the principal component of the elastic fiber system of the ligament. These are in continuity with the elaunin and oxytalan fibers which are intermingled with the muscle cells of the vessels and duodenal wall, and fat cells of the ligament. Part of the muscle bundles of the external, longitudinal, muscle layer of the Cluodenum is anchored in the adventitial and subserosal collagen and elastic fiber framework of the organ while part inserts directly into the fibrous framework of the ligament. The fibrous system of the ligament is continuous with that of the subserosa and adventitia of the duodenum. © 1995 WiIey-Liss, Inc.     

Forensic clinical anatomy: A new field of study with application to medicolegal issues

Forensic clinical anatomy is a new practical application of the discipline of Clinical Anatomy for ascertaining and evaluating medicolegal questions. In particular, individual anatomy (normal anatomy, anatomical variations, age‐, disease‐, or surgery‐related modifications) can acquire significant relevance in various fields of legal medicine such as child abuse, sudden death, medical responsibility and/or liability, personal injury and damage. Anatomical data of forensic interest frequently arise from the correct application of methods of ascertainment; anatomical methods may then be required for further comprehensive analysis. The rigorous interpretation of anatomical data, derived from the ascertainment phase and analyzed on the basis of pertinent literature, can be pivotal for the correct application of evaluation criteria in various forensic contexts. Clin. Anat. 30:2–5, 2017. © 2016 Wiley Periodicals, Inc.     

The human meniscus: A review of anatomy,function, injury,and advances in treatment

Meniscal injuries are recognized as a cause of significant musculoskeletal morbidity. The menisci are vital for the normal function and long‐term health of the knee joint. The purpose of this review is to provide current knowledge regarding the anatomy and biomechanical functions of the menisci, incidence, injury patterns and the advancements in treatment options of meniscal injury. A literature search was performed by a review of PubMed, Google Scholar, MEDLINE, and OVID for all relevant articles published between 1897 and 2014. This study highlights the anatomical and biomechanical characteristics of the menisci, which may be relevant to injury patterns and treatment options. An understanding of the normal anatomy and biomechanical functions of the knee menisci is a necessary prerequisite to understanding pathologies associated with the knee. Clin. Anat. 28:269–287, 2015. © 2014 Wiley Periodicals, Inc.     

Fascial bundles of the infraspinatus fascia: anatomy,function, and clinical considerations

The infraspinatus fascia is a tough sheet of connective tissue that covers the infraspinatus fossa of the scapula and the muscle within. Muscle fibers originate from the fossa and fascia and then travel laterally to insert on the greater tubercle of the humerus. Frequently the infraspinatus fascia is quickly removed to appreciate the underlying muscle, but the fascia is an interesting and complex structure in its own right. Despite having a characteristic set of fascial bundles, no contemporary anatomy texts or atlases describe the fascia in detail. The infraspinatus fascia was dissected in detail in 11 shoulders, to characterize the fascial bundles and connections that contribute to it. Thereafter, 70 shoulders were dissected to tabulate the variability of the fascial bundles and connections. Six characteristic features of the infraspinatus fascia were noted: a medial band, an inferior‐lateral band, and superior‐lateral band of fascia, insertion of the posterior deltoid into the infraspinatus fascia, a transverse connection from the posterior deltoid muscle to the infraspinatus fascia, and a retinacular sheet deep to the deltoid and superficial to the infraspinatus and teres minor muscles. Although other structures of the shoulder are more frequently injured, the infraspinatus fascia is involved in compartment syndromes and the fascial bundles of this structure are certain to impact the biomechanical function of the muscles of the posterior shoulder.     

Bygone theatres of events: A history of human anatomy and dissection

Over the last four millennia, the discipline of anatomy and its relationships with medicine and society have evolved dramatically. Human dissection, the perennial tool for anatomical discovery and education, has both guided this evolution and matured alongside it. Soon after the first cadaveric dissections recorded in ancient Greece, China, India, and Persia, clear endorsements of its practice fell largely silent in the anatomical record for 1,500 years before reappearing in Europe at the dawn of the Renaissance. Between the 13th and 18th centuries CE, the performance of anatomical dissection became a popular form of education and public entertainment, and the demand for human cadavers steadily increased among European anatomical schools while supply remained limited by legal statute. This gave rise to an informal group of amateur and professional body snatchers called the Resurrectionists and, later, inspired the Anatomy Act of 1832 CE. In the 20th and 21st centuries CE, voluntary body bequeathal programs have enabled the practice of human dissection to continue in academic centers as a cornerstone of anatomical education, now with a newfound focus on the development of affective skills. This article provides an abridged account of anatomy's development, highlighting key moments in its growth, the valuable contributions of many different societies to the discipline, and the important roles of several luminary anatomists of antiquity. Within the broader context of this history, it offers an overview of anatomical dissection's evocative past, spanning from its inception to its present-day practice.     

Potential impact of functional biomolecules-enriched foods on human health: A randomized controlled clinical trial

Naturally occurring milk compounds have recently been investigated for their health-promoting properties; in fact, their anti-microbial, immuno-modulatory, antioxidant and anti-thrombotic activities, have increasingly gained interest within the scientific community. We have reported a translational, randomized, controlled clinical trial (RCT) on human subjects with a moderate to high cardiovascular risk, and a body mass index (BMI) >25.1 kg/m2, to evaluate the clinical impact of biomolecules-enriched Mediterranean Buffalo (Bubalus bubalis) milk and its derived dairy foods, produced with innovative breeding techniques. The experimental arm involved patients that followed a diet including the above-described products (treated group; n= 11); the control arm was based on a diet including cow milk and its dairy products (control group; n= 9). The results of this study have been statistically evaluated, pointing out a specific significance related to the comparative analysis of the blood pressure among the 2 arms; in fact, this value showed a significant improvement in an extremely short experimental time. Nevertheless, this study also reported not-significant results that were indicative of an interesting and promising tendency in modulating specific diet-depending haematological and biomedical values. In conclusion, this RCT has assessed that the foods derived from buffalo milk naturally enriched with biomolecules, was able to improve the overall blood glucose levels, the BMI and the body weight. These preliminary results are suitable for the design of future strategies in the prevention of cardiometabolic diseases, thus improving the overall quality of life and the policies of healthcare management.     

Fiber type characterization of striated muscles related to micturition in female rabbits

Pelvic and perineal striated muscles are relevant for reproduction and micturition in female mammals. Damage to these muscles is associated with pelvic organ prolapse and stress urinary incontinence. The fiber type composition of skeletal muscle influences the susceptibility for damage and/or regeneration. The aim of the present study was to determine the fiber type composition of a perineal muscle, the bulbospongiosus, and a pelvic muscle, the pubococcygeus. Both muscles were harvested from adult female rabbits (8–10 months old). NADH-TR (nicotinamide adenine dinucleotide tetrazolium reductase) histochemistry was undertaken to identify oxidative and glycolytic muscle fibers. Alkaline (pH 9.4) ATP-ase (actomyosin adenosine triphosphatase) histochemistry was used to classify type I, type IIb or type IIa/IId muscle fibers. Results showed that the content of glycolytic fibers in the bulbospongiosus muscle was higher than that of oxidative fibers. Meanwhile, the opposite was true for the pubococcygeus. In the bulbospongiosus muscle, the content of type IIb muscle fibers was higher than that of type I, but was similar to that of type IIa/IId. In contrast, the content of each fiber type was similar in the pubococcygeus muscle. The relative proportion of fibers in bulbospongiosus and pubococcygeus muscles is consistent with their function during voiding and storage phases of micturition.     

Escaping from Flatland: clinical and biological aspects of human mammary duct anatomy in three dimensions

Accurate knowledge of breast duct anatomy in three dimensions is needed to understand normal breast development, how intraepithelial neoplasia may spread through a breast, and the potential for diagnostic and therapeutic access to breast parenchyma via the nipple. This paper reports three related exploratory studies. In study 1, the median number of milk-collecting ducts in the nipple was determined in 72 breasts excised for cancer; in study 2, the volumes of all 20 complete duct systems ("lobes") in an autopsy breast were measured from 2 mm serial "subgross" sections; and in study 3, a 3D digital model of all collecting ducts in a mastectomy nipple was made from 68 100 micro m serial sections. The mastectomy nipples contained 11-48 central ducts (median 27, inter-quartile range 21-30). In the autopsy breast, the largest "lobe" drained 23% of breast volume; half of the breast was drained by three ducts and 75% by the largest six. Conversely, eight small duct systems together accounted for only 1.6% of breast volume. The 3D model of the nipple revealed three distinct nipple duct populations. Seven ducts maintained a wide lumen up to the skin surface (population A); 20 ducts tapered to a minute lumen at their origin in the vicinity of skin appendages (population B) on the apex of the nipple; and a minor duct population (C) arose around the base of the papilla. Major variations in duct morphology and extent define highly variable territories in which intraepithelial neoplasia could grow. While population A ducts appear accessible to duct endoscopy or lavage, population B and population C ducts may be less accessible.