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Anatomical Science International Jul 2023The purpose of this review is to present our researches on the pelvic outlet muscles, including the pelvic floor and perineal muscles, which are responsible for urinary... (Review)
Review
The purpose of this review is to present our researches on the pelvic outlet muscles, including the pelvic floor and perineal muscles, which are responsible for urinary function, defecation, sexual function, and core stability, and to discuss the insights into the mechanism of pelvic floor stabilization based on the findings. Our studies are conducted using a combination of macroscopic examination, immunohistological analysis, 3D reconstruction, and imaging. Unlike most previous reports, this article describes not only on skeletal muscle but also on smooth muscle structures in the pelvic floor and perineum to encourage new understanding. The skeletal muscles of the pelvic outlet are continuous, which means that they share muscle bundles. They form three muscle slings that pass anterior and posterior to the anal canal, thus serving as the foundation of pelvic floor support. The smooth muscle of the pelvic outlet, in addition to forming the walls of the viscera, also extends in three dimensions. This continuous smooth muscle occupies the central region of the pelvic floor and perineum, thus revising the conventional understanding of the perineal body. At the interface between the levator ani and pelvic viscera, smooth muscle forms characteristic structures that transfer the lifting power of the levator ani to the pelvic viscera. The findings suggest new concepts of pelvic floor stabilization mechanisms, such as dynamic coordination between skeletal and smooth muscles. These two types of muscles possibly coordinate the direction and force of muscle contraction with each other.
Topics: Pelvic Floor; Perineum; Muscle, Skeletal; Muscle, Smooth; Anal Canal
PubMed: 36961619
DOI: 10.1007/s12565-023-00717-7 -
Comprehensive Physiology Sep 2016Pain involving thoracic, abdominal, or pelvic organs is a common cause for physician consultations, including one-third of chronic pain patients who report that visceral... (Review)
Review
Pain involving thoracic, abdominal, or pelvic organs is a common cause for physician consultations, including one-third of chronic pain patients who report that visceral organs contribute to their suffering. Chronic visceral pain conditions are typically difficult to manage effectively, largely because visceral sensory mechanisms and factors that contribute to the pathogenesis of visceral pain are poorly understood. Mechanistic understanding is particularly problematic in "functional" visceral diseases where there is no apparent pathology and pain typically is the principal complaint. We review here the anatomical organization of the visceral sensory innervation that distinguishes the viscera from innervation of all other tissues in the body. The viscera are innervated by two nerves that share overlapping functions, but also possess notably distinct functions. Additionally, the visceral innervation is sparse relative to the sensory innervation of other tissues. Accordingly, visceral sensations tend to be diffuse in character, are typically referred to nonvisceral somatic structures and thus are difficult to localize. Early arguments about whether the viscera were innervated ("sensate") and later, whether innervated by nociceptors, were resolved by advances reviewed here in the anatomical and functional attributes of receptive endings in viscera that contribute to visceral pain (i.e., visceral nociceptors). Importantly, the contribution of plasticity (i.e., sensitization) of peripheral and central visceral nociceptive mechanisms is considered in the context of persistent, chronic visceral pain conditions. The review concludes with an overview of the functional anatomy of visceral pain processing. © 2016 American Physiological Society. Compr Physiol 6:1609-1633, 2016.
Topics: Animals; Humans; Neurons, Afferent; Viscera; Visceral Pain
PubMed: 27783853
DOI: 10.1002/cphy.c150049 -
Journal of the American Animal Hospital... 2018Perineal hernia refers to the failure of the muscular pelvic diaphragm to support the rectal wall, resulting in herniation of pelvic and, occasionally, abdominal viscera... (Review)
Review
Perineal hernia refers to the failure of the muscular pelvic diaphragm to support the rectal wall, resulting in herniation of pelvic and, occasionally, abdominal viscera into the subcutaneous perineal region. The proposed causes of pelvic diaphragm weakness include tenesmus associated with chronic prostatic disease or constipation, myopathy, rectal abnormalities, and gonadal hormonal imbalances. The most common presentation of perineal hernia in dogs is a unilateral or bilateral nonpainful swelling of the perineum. Clinical signs do occur, but not always. Clinical signs may include constipation, obstipation, dyschezia, tenesmus, rectal prolapse, stranguria, or anuria. The definitive diagnosis of perineal hernia is based on clinical signs and findings of weak pelvic diaphragm musculature during a digital rectal examination. In dogs, perineal hernias are mostly treated by surgical intervention. Appositional herniorrhaphy is sometimes difficult to perform as the levator ani and coccygeus muscles are atrophied and unsuitable for use. Internal obturator muscle transposition is the most commonly used technique. Additional techniques include superficial gluteal and semitendinosus muscle transposition, in addition to the use of synthetic implants and biomaterials. Pexy techniques may be used to prevent rectal prolapse and bladder and prostate gland displacement. Postoperative care involves analgesics, antibiotics, a low-residue diet, and stool softeners.
Topics: Animals; Dog Diseases; Dogs; Hernia; Herniorrhaphy; Perineum
PubMed: 29757662
DOI: 10.5326/JAAHA-MS-6490 -
American Journal of Obstetrics and... Jan 2020Without cesarean delivery, obstructed labor can result in maternal and fetal injuries or even death given a disproportion in size between the fetus and the maternal... (Review)
Review
Without cesarean delivery, obstructed labor can result in maternal and fetal injuries or even death given a disproportion in size between the fetus and the maternal birth canal. The precise frequency of obstructed labor is difficult to estimate because of the widespread use of cesarean delivery for indications other than proven cephalopelvic disproportion, but it has been estimated that at least 1 million mothers per year are affected by this disorder worldwide. Why is the fit between the fetus and the maternal pelvis so tight? Why did evolution not lead to a greater safety margin, as in other primates? Here we review current research and suggest new hypotheses on the evolution of human childbirth and pelvic morphology. In 1960, Washburn suggested that this obstetrical dilemma arose because the human pelvis is an evolutionary compromise between two functions, bipedal gait and childbirth. However, recent biomechanical and kinematic studies indicate that pelvic width does not considerably affect the efficiency of bipedal gait and thus is unlikely to have constrained the evolution of a wider birth canal. Instead, bipedalism may have primarily constrained the flexibility of the pubic symphysis during pregnancy, which opens much wider in most mammals with large fetuses than in humans. We argue that the birth canal is mainly constrained by the trade-off between 2 pregnancy-related functions: while a narrow pelvis is disadvantageous for childbirth, it offers better support for the weight exerted by the viscera and the large human fetus during the long gestation period. We discuss the implications of this hypothesis for understanding pelvic floor dysfunction. Furthermore, we propose that selection for a narrow pelvis has also acted in males because of the role of pelvic floor musculature in erectile function. Finally, we review the cliff-edge model of obstetric selection to explain why evolution cannot completely eliminate cephalopelvic disproportion. This model also predicts that the regular application of life-saving cesarean delivery has evolutionarily increased rates of cephalopelvic disproportion already. We address how evolutionary models contribute to understanding and decision making in obstetrics and gynecology as well as in devising health care policies.
Topics: Animals; Biological Evolution; Cephalopelvic Disproportion; Cesarean Section; Female; Gait; Hominidae; Humans; Parturition; Pelvic Bones; Pelvimetry; Pelvis; Pregnancy; Pubic Symphysis; Selection, Genetic
PubMed: 31251927
DOI: 10.1016/j.ajog.2019.06.043 -
Physical Medicine and Rehabilitation... May 2022For patients with chronic pain or cancer-related pain, the most common indication for sympathetic block is to control visceral pain arising from malignancies or other... (Review)
Review
For patients with chronic pain or cancer-related pain, the most common indication for sympathetic block is to control visceral pain arising from malignancies or other alterations of the abdominal and pelvic viscera. When it is recalcitrant to conservative care, or if the patient is intolerant to pharmacotherapy, consideration of sympathetic blocks or neurolytic procedures is considered. Potential advantages of a neurolytic procedure, compared with spinal and epidural anesthetic infusions, include cost savings and avoidance of hardware. Interventional therapies that target afferent visceral innervation via the sympathetic ganglia offer effective and durable analgesia and improve multiple metrics of quality of life.
Topics: Autonomic Nerve Block; Celiac Plexus; Humans; Hypogastric Plexus; Quality of Life; Visceral Pain
PubMed: 35526980
DOI: 10.1016/j.pmr.2022.01.010