Response of the urethral and intracorporeal pressures to cavernosus muscle stimulation: Role of the muscles in erection and ejaculation

Shafik, Ahmed

doi:10.1016/s0090-4295(99)80165-4

Cited by 43 publications

(20 citation statements)

References 9 publications

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“…The EAS was stimulated and the response of the EUS, PR, LA and BC was determined. Following the previously described technique [14][15][16] ( Fig. 2).…”

Section: Methodsmentioning

confidence: 99%

A new concept of the anatomy of the anal sphincter mechanism and the physiology of defecation: Mass contraction of the pelvic floor muscles

Shafik

1998

Int Urogynecol J

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We have previously demonstrated both anatomically and physiologically that the external anal (EAS) and urethral (EUS) sphincters and the bulbocavernosus muscle (BC) originate from the puborectalis muscle (PR). It is hypothesized that stimulation of any of these muscles would lead to contraction of all the others. Because the levator ani (pubococcygeus) muscle (LA) also has the same innervation as the above-mentioned muscles, it is further suggested that it, too, contracts reflexly upon stimulation of any of those muscles. The purpose of this study was to test this hypothesis. The study comprised 18 healthy volunteers (mean age 36.6 +/- 8.4 years; 10 men, 8 women). The EAS was stimulated and the response of the EUS, PR, LA and BC was determined. Each muscle was thereafter stimulated separately and the response of the other pelvic floor muscles registered. Stimulation of any of the pelvic floor muscles effected an increased EMG activity of the rest of the muscles. The muscle contraction was instantaneous with no latency in all the muscles except the LA EMG activity, which showed a mean latency of 21.3 +/- 6.6 ms. The pelvic floor muscles' response seems to be attributable to muscle stimulation both directly and indirectly through activation of pudendal nerve fibers in the muscles. The study demonstrated that the pelvic floor muscles behave as one muscle: they contract or relax en masse. This 'mass contraction' might explain some of the physiologic phenomena that occur during pelvic organ evacuation. However, besides this mass contraction, a voluntary 'selective' individual muscle activity exists by which each individual muscle acts independently of the others.

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“…The EAS was stimulated and the response of the EUS, PR, LA and BC was determined. Following the previously described technique [14][15][16] ( Fig. 2).…”

Section: Methodsmentioning

confidence: 99%

A new concept of the anatomy of the anal sphincter mechanism and the physiology of defecation: Mass contraction of the pelvic floor muscles

Shafik

1998

Int Urogynecol J

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“…During ejaculation, pressures of more than 5 metres water pressure have been found in the prostatic urethra. 27 When rhythmic contractions of the pelvic muscles (for the purpose of this article defined as 'somatic ejaculation') occur, there will be moments of relaxation of the urethral sphincter, and then semen will leak into the bulbar urethra, dilating the bulbous and resulting in a urethrobulbocavernous or urethro-genital reflex contraction and expelling semen out of the penis. 28 More recently a 'spinal pattern generator' model was developed and extensively tested to literature findings.…”

Section: Ejaculationmentioning

confidence: 99%

Neuroanatomy and neurophysiology related to sexual dysfunction in male neurogenic patients with lesions to the spinal cord or peripheral nerves

et al. 2010

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Study design: Review article. Objectives: The neuroanatomy and physiology of psychogenic erection, cholinergic versus adrenergic innervation of emission and the predictability of outcome of vibration and electroejaculation require a review and synthesis. Setting: University Hospital Belgium. Methods: We reviewed the literature with PubMed 1973PubMed -2008. Results: Erection, emission and ejaculation are separate phenomena and have different innervations. It is important to realize, which are the afferents and efferents and where the motor neuron of the end organ is located. When interpreting a specific lesion it is important to understand if postsynaptic fibres are intact or not. Afferents of erection, emission and ejaculation are the pudendal nerve and descending pathways from the brain. Erection is cholinergic and NO-mediated. Emission starts cholinergically (as a secretion) and ends sympathetically (as a contraction). Ejaculation is mainly adrenergic and somatic. For vibratory-evoked ejaculation, the reflex arch must be complete; for electroejaculation, the postsynaptic neurons (paravertebral ganglia) must be intact. Conclusion: Afferents of erection, emission and ejaculation are the pudendal nerve and descending pathways from the brain. Erection is cholinergic and NO-mediated. Emission starts cholinergically (as a secretion) and ends sympathetically (as a contraction). Ejaculation is mainly adrenergic and somatic. In neurogenic disease, a good knowledge of neuroanatomy and physiology makes understanding of sexual dysfunction possible and predictable. The minimal requirement for the success of penile vibration is a preserved reflex arch and the minimal requirement for the success of electroejaculation is the existence of intact post-ganglionic fibres.

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“…Earlier studies have demonstrated the role of the pelvic oor muscles and sphincters in erection and ejaculation [38,39].…”

Section: Role Of Levator Ani In Erection and Ejaculationmentioning

confidence: 99%

The Role of the Levator Ani Muscle in Evacuation, Sexual Performance and Pelvic Floor Disorders

Shafik

2000

Int Urogynecol J

134

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This paper reviews the role of the levator ani muscle (LAM) in evacuation, sexual performance and pelvic floor disorders. The LAM fixes the vesical neck, anorectal junction and vaginal fornices to the side wall of the pelvis by means of the suspensory sling and hiatal ligament. On contraction it shares in the mechanism of evacuation (urination, defecation). During the sexual act vaginal distension by the erect penis evokes the vaginolevator and vaginopuborectalis reflexes, with a resulting LAM contraction. The LAM also contracts upon stimulation of the clitoris or cervix uteri, an action mediated through clitoromotor and cervicomotor reflexes. LAM contraction leads to upper vagina ballooning, which acts as receptacle for semen collection, to uterine elevation and straightening and to elongation and narrowing of the vagina. These actions enhance the sexual response and prepare the uterus and vagina for the reproductive process. During ejaculation LAM contraction facilitates semen ejection. Levator subluxation and sagging leads to levator dysfunction syndrome, which may present as pudendal canal syndrome.

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Response of the urethral and intracorporeal pressures to cavernosus muscle stimulation: Role of the muscles in erection and ejaculation

Cited by 43 publications

References 9 publications

A new concept of the anatomy of the anal sphincter mechanism and the physiology of defecation: Mass contraction of the pelvic floor muscles

A new concept of the anatomy of the anal sphincter mechanism and the physiology of defecation: Mass contraction of the pelvic floor muscles

Neuroanatomy and neurophysiology related to sexual dysfunction in male neurogenic patients with lesions to the spinal cord or peripheral nerves

The Role of the Levator Ani Muscle in Evacuation, Sexual Performance and Pelvic Floor Disorders

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