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Erectile Dysfunction
Published in Botros Rizk, Ashok Agarwal, Edmund S. Sabanegh, Male Infertility in Reproductive Medicine, 2019
Mark Johnson, Marco Falcone, Tarek M. A. Aly, Amr Abdel Raheem
This neurovascular event results in dilatation of the arteries, expansion of the sinusoidal spaces, and an overall reduction in the peripheral vascular resistance. This results in a net inflow of blood into the penis, resulting in expansion or tumescence. The thick tunica albuginea surrounding the corporal bodies limits expansion and, therefore, increases intracorporal pressure. As pressure increases, venous outflow reduces, and once the emissary veins between the inner circular and outer longitudinal layers of the tunica are compressed, the full-erection stage is reached. Further increases in pressure are achieved by the contraction of the ischiocavernosus muscle [5].
Anatomy of the vulva
Published in Miranda A. Farage, Howard I. Maibach, The Vulva, 2017
Aikaterini Deliveliotou, George Creatsas
Three types of muscle exist in the vulva: The ischiocavernosus muscle compresses the crura and lowers the clitoris. It originates from the ischial tuberosity and inserts at the ischiopubic bone.The bulbocavernosus muscle compresses the vestibular bulb and dorsal vein of the clitoris. It originates from the perineal body and inserts into the posterior aspect of the clitoris; some fibers pass above the dorsal vein of the clitoris in a sling-like fashion.The superficial transverse perineal muscle holds the perineal body fixed. It originates from the ischial tuberosity and inserts at the central perineal tendon.
The Conception Vessel (CV)
Published in Narda G. Robinson, Interactive Medical Acupuncture Anatomy, 2016
Clinical Relevance: Superficial and deep branches of the pudendal nerve supply CV 1. The pudendal nerve divides into inferior rectal nerves, the perineal nerve, and the dorsal nerve of the penis or clitoris. In addition to supplying the external genitalia, the pudendal nerve innervates the urethral and anal sphincters, the scrotum, along with the bulbospongiosus and ischiocavernosus muscles. These muscles contract during ejaculation/orgasm. Pudendal nerve damage after difficult childbirth, reconstructive surgery or extended bicycling (e.g., spin class)11 can cause a temporary loss of function or persistent and painful neuralgia. Pudendal neuropathy produces a sensation of heaviness or burning along the route it traverses. It may cause the patient to feel as though the vagina or rectum contains foreign bodies; sitting worsens the condition.2
Aging and erectile function
Published in The Aging Male, 2020
David R. Meldrum, Marge A. Morris, Joseph C. Gambone, Katherine Esposito
ICP up to 2–4 times systolic levels has been recorded in the human male [39], but pressure within the CC (and therefore penile rigidity) solely from inflow of blood cannot exceed systolic blood pressure. The bulbocavernosal muscles augment erectile potency by partially surrounding the CC to constrict venous outflow and directly increase ICP [39]. Reflex contractions of the PF muscles have been shown to occur due to distention of the CC [40] and pressure on the glans penis [41], resulting in increased ICP with coital thrusting. The ischiocavernosal muscles also overlie and insert onto the penile tunica to allow their contractions to improve erectile quality. In a study of six cadavers of relatively young, sexually active men [42], the bulbocavernosus muscles were described as partially encircling the CC and mostly inserting into the ventral thickening of the tunica. The CC was described as entrapped in the ischiocavernosus muscle with its muscle fibers aligned in a longitudinal direction and inserting into the outer longitudinal collagen bundles of the tunica. The PF muscles were less developed and their points of attachment to the tunica were thinner (p<.01) in the older sexually less active men.
Phantom Penis: Extrapolating Neuroscience and Employing Imagination for Trans Male Sexual Embodiment
Published in Studies in Gender and Sexuality, 2020
During sexual activity, the penis stiffens and extends in length. However, the visible penis has no bone or voluntary muscle. Although the penis appears to move itself, it is passively moved by adjacent muscles and a hydraulic system. Its erotic momentum calls on the forceful movement by hips and torso or being moved upon. Several smooth (involuntary) muscles, under the influence of the autonomic nervous system, are located in the (proximal, internal) root of the penis. The ischiocavernosus muscles aid in the increased inflow and decreased outflow of blood to achieve and sustain erection—that primary accomplishment of the penis, which announces itself proprioceptively via a high density of stretch receptors. Involuntary rhythmic motions of the bulbocavernosous muscles aid ejaculation. In a discussion following Heusner’s article on phantom penises, Yakovlev succinctly elucidates the motor mediocrity of the axial penis: “The genitalia are not outjuttings of the body wall, but rather viscera extruded … . The testicle and penis are endowed with only what may be called cremasteric motion of pulling up—a motion of a part of the body upon the body, with the fulcrum in the body” (1950, p. 132).
Female genito-pelvic reflexes: an overview
Published in Sexual and Relationship Therapy, 2019
Symen K. Spoelstra, Esther R. Nijhuis, Willibrord C. M. Weijmar Schultz, Janniko R. Georgiadis
The main somatic nerve of the perineum is the pudendal nerve, which has somatosensory and somatomotor tributaries, and which divides into three main branches (inferior rectal, perineal, dorsal penile/clitoral) at the level of the levator ani muscle. The muscles that embryonically derive from the cloacal sphincter (external anal and urethral sphincter, superficial transverse perineal muscle, bulbocavernosus muscle and ischiocavernosus muscle) are all innervated by pudendal nerve fibres originating in a specialized sacral motor neuronal pool called Onuf's nucleus (Iwata, Inoue, & Mannen, 1993; Onuf, 1899). As Onuf motoneurons innervate striated muscles but also are known to be relatively unaffected by somatic motoneuron diseases like amyotrophic lateral sclerosis (Mannen, Iwata, Toyokura, & Nagashima, 1977), they have been proposed to be of a mixed somatic/autonomic type (Kihira, Yoshida, Yoshimasu, Wakayama, & Yase, 1997). Interestingly, the pudendal nerve seems less involved in the innervation of the levator ani muscle. A separate nerve, the “levator ani nerve” (Wallner, Maas, Dabhoiwala, Lamers, & De Ruiter, 2010), arising from the ventral ramus of the third and fourth sacral nerves, is held to innervate the pelvic diaphragm. In at least 50% of cadavers studied, the pudendal nerve also contributed to innervation of the levator ani muscle, especially in regards to the medial portions (puborectal and pubococcygeal muscles) (Rock JA, 2003).