A new concept of the anatomy of the anal sphincter mechanism and the physiology of defecation

Shafik, Ahmed

doi:10.1007/bf02586911

Cited by 39 publications

(70 citation statements)

References 7 publications

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“…As all of the pelvic floor muscles except the LA arise fiom the PR, as has been proved both anatomically [5,6] and physiologically [7], stimulation of each individual muscle effects contraction of the other muscles by direct stimulation as well as by stimulation of sensory and motor fibers of the pudendal nerve, which lie in the muscle. Stimulation of the motor fibers of the pudendal nerve induces muscle contraction only of the stimulated muscle; meanwhile, stimulation of sensory fibers of the pudendal nerve induces reflex contraction of not only the stimulated muscle but also of all of the muscles supplied by the pudendal nerve, i.e.…”

Section: Discussionmentioning

confidence: 99%

“…Previous studies have demonstrated both anatomically [5,6] and physiologically [7] that the puborectalis muscle (PR) gives rise to the external anal (EAS) and urethral (EUS) sphincters ( Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, the bulbocavernosus muscle (BC) was found to be a part of the EAS, and is thus considered also to arise from the PR [8]. Individual sphincters arising from the puborectalis muscle, which acts as a common sphincter for the pelvic organs (from Shafik [5]). As all of these muscles originate from one muscle, the PR, it is to be expected that upon stimulation of any individual muscle the group would respond collectively, especially as they share innervation from the pudendal nerve.…”

Section: Introductionmentioning

confidence: 99%

“…It is further hypothesized that because of its innervation also by the pudendal nerve, the levator ani (LA) would share in the contraction of the aforementioned muscles when they are stimulated. By 'LA', we mean the pubococcygeus muscle, which is the functional part of the LA in humans [5]. The levator plate is the transverse portion of the levator funnel [5].…”

Section: Introductionmentioning

confidence: 99%

“…By 'LA', we mean the pubococcygeus muscle, which is the functional part of the LA in humans [5]. The levator plate is the transverse portion of the levator funnel [5]. Other investigators [2,[9][10][11][12] have reported the fusion of the EAS and the anterior fibers of the LA, and Porter [13] has also stressed the functional integration of this striated muscle complex.…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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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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Anal fistula

Seow‐Choen

Nicholls

1992

Journal of British Surgery

138

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Anal fistula is a common cause of chronic irritation to both patients and surgeons. Treatment failure rates may be decreased by a good appreciation of normal anorectal anatomy and fistula pathoanatomy, as well as a wide and practical knowledge of the possible treatment regimens. The various treatment options available for acute abscesses as well as simple and complex anal fistulae are presented and discussed. Identification of the patient at risk of postoperative anal incontinence or of the difficult or high fistula may allow treatment in a specialized proctology unit.

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Nerves in the intersphincteric space of the human anal canal with special reference to their continuation to the enteric nerve plexus of the rectum

Hieda

Cho

Arakawa³

et al. 2013

Clinical Anatomy

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In the intersphincteric space of the anal canal, nerves are thought to "change" from autonomic to somatic at the level of the squamous-columnar epithelial junction of the anal canal. To compare the nerve configuration in the intersphincteric space with the configuration in adjacent areas of the human rectum, we immunohistochemically assessed tissue samples from 12 donated cadavers, using antibodies to S100, neuronal nitric oxide synthase (nNOS), and tyrosine hydroxylase (TH). Antibody to S100 revealed a clear difference in intramuscular nerve distribution patterns between the circular and longitudinal muscle layers of the most inferior part of the rectum, with the former having a plexus-like configuration, while the latter contained short, longitudinally running nerves. Most of the intramural ganglion cells in the anal canal were restricted to above the epithelial junction, but some were located just below that level. Near or at the level of the epithelial junction, the nerves along the rectal adventitia and Auerbach's nerve plexus joined to form intersphincteric nerves, with all these nerves containing both nNOS-positive parasympathetic and TH-positive sympathetic nerve fibers. Thus, it was histologically difficult to distinguish somatic intersphincteric nerves from the autonomic Auerbach's plexus. In the intersphincteric space, the autonomic nerve elements with intrapelvic courses seemed to "borrow" a nerve pathway in the peripheral branches of the pudendal nerve. Injury to the intersphincteric nerve during surgery may result in loss of innervation in the major part of the internal anal sphincter.

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A new concept of the anatomy of the anal sphincter mechanism and the physiology of defecation

Cited by 39 publications

References 7 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

Anal fistula

Nerves in the intersphincteric space of the human anal canal with special reference to their continuation to the enteric nerve plexus of the rectum

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