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The abdomen
Published in Peter Kopelman, Dame Jane Dacre, Handbook of Clinical Skills, 2019
Peter Kopelman, Dame Jane Dacre
In the large bowel, most contractions are non-propulsive and serve to delay rather than promote transit. This accounts for the paradox that in diarrhoea, intraluminal pressure records show decreased activity, and in constipation increased activity. After receiving the food residues, the caecum exhibits mixing activity and then slowly contracts so that food residues reach the transverse colon over 6–10 hours. One to three times each day, mass movements occur and propel the contents into the descending and sigmoid colon. Continence is maintained by two sphincters. The internal sphincter reflects the activity of the circular muscle of the intestine; it is usually in tonic contraction. The external sphincter also shows continuous resting activity. Both the external and puborectalis muscle are inhibited on defecation and micturition.
Free Transplantation of Striated Muscle
Published in Han C. Kuijpers, Colorectal Physiology: Fecal Incontinence, 2019
Stephens,7,8 in his important work on congenital imperforate anus, emphasized the importance of the puborectalis muscle for anal continence. The puborectalis muscle is the caudal, medial part of the funnel-like muscular pelvic floor. It arises from the back of the pubic bone and is directed backwards on each side of the lower part of the rectum. Corresponding fibers on both sides unite to form a muscular sling behind the rectum, thus creating the anorectal angle. The contraction of the puborectalis muscle pushes the rectum forward and upward, thereby making the angle between the rectum and anal canal more acute, preventing passage of their contents.8,9 The puborectalis contracts as soon as increased intrarectal pressure endangers continence.10 The importance of the puborectalis in maintaining anal continence is paramount and it is probable that the function of the external anal sphincter is limited to reacting to sudden increases in rectal pressure, and in emptying the anal canal distal to the puborectalis sling.
Physiology
Published in Peter Sagar, Andrew G. Hill, Charles H. Knowles, Stefan Post, Willem A. Bemelman, Patricia L. Roberts, Susan Galandiuk, John R.T. Monson, Michael R.B. Keighley, Norman S. Williams, Keighley & Williams’ Surgery of the Anus, Rectum and Colon, 2019
Anwen Williams, Martyn D. Evans
Colonic contractions ensure propulsion of faeces into the rectal reservoir that accommodates by relaxation of its muscular walls and an increase in rectal capacitance. The tone of the puborectalis sling and the internal and external anal sphincters ensures that the rectum can retain its contents. The puborectalis muscle forms the pelvic floor and surrounds the rectum posteriorly and laterally to create an angle between the anus and rectum to help preserve continence. During defaecation, the puborectalis muscle relaxes reducing the sling effect and therefore the anorectal angle. The rectum straightens as a result, facilitating rectal emptying as the anal sphincters relax. This whole process is entirely dependent on the nervous innervation of the rectum and anus. During normal rectal emptying, the following changes are observed: (1) As straining begins, abdominal pressure produces a slight concavity of the anterior rectal wall. (2) The pelvic floor descends. (3) The anorectal angle widens. (4) The anal canal begins to open, shortens and becomes funnel-shaped. (5) Rectal evacuation begins and emptying is completed. (6) A slight degree of rectal wall intussusception may occur.
Restoration of bladder neck activity and levator hiatus dimensions in Asian primipara: a prospective study
Published in Journal of Obstetrics and Gynaecology, 2023
Zexuan Yang, Liuying Zhou, Liwen Yang, Hui He
Pelvic floor muscle training helps to reduce prolapse and overactive bladder symptoms in women with PFD (Hagen et al.2017, Toprak Celenay et al.2022). However, the optimal initial timing of the intervention for secondary prevention of PFD in puerpera is not clear. Waarsenburg et al found that the structure of the puborectalis muscle largely recovered during the first three weeks postpartum, while the stretch of the puborectalis muscle consistently increased 24 weeks after the first vaginal delivery (Van de Waarsenburg et al.2018). These findings suggested that the best window to initiate secondary prevention of PFD may be within the first 3 weeks postpartum. However, the early regeneration of bladder neck activity after first vaginal delivery is not well characterised; in addition, whether the changes of BND are associated with the changes in levator hiatus dimensions is not clear.
Botulinum toxin type-A infiltration of the external anal sphincter to treat outlet constipation in motor incomplete spinal cord injury: pilot cohort study
Published in Scandinavian Journal of Gastroenterology, 2021
Margarita Vallès, Sergiu Albu, Hatice Kumru, Fermín Mearin
Some studies indicate that BTX-A infiltration of the external anal sphincter (EAS) or the puborectalis muscle may improve outlet-type constipation [8,9]. Biofeedback is the standard treatment of the puborectalis syndrome [10], however when it fails the BTX-A infiltration of the EAS or puborectalis muscle can improve symptoms of constipation [9]. Furthermore, BTX-A infiltration have been shown to improve rectal emptying in patients with Parkinson's disease affected by outlet-obstruction constipation [11,12]. Nevertheless, the use of BTX-A infiltration in the treatment of neurogenic bowel symptoms in subjects with SCI has not been investigated. As we have published previously, one of the main pathophysiological mechanisms of bowel dysfunction in patients with motor-complete SCI below the T7 level, and motor-incomplete SCI, is outlet defecation with paradoxical contraction of the pelvic floor or lack of relaxation during the defecatory manoeuvre [13,14].
Physiotherapist management of a patient with spastic perineal syndrome and subsequent constipation: a case report
Published in Physiotherapy Theory and Practice, 2021
Shankar Ganesh, Mritunjay Kumar
Isolated defecatory dysfunction can occur in 25% of the persons suffering from constipation (Lembo and Camilleri, 2003). In the normal state, the anorectal angle is maintained by the tonic contraction of the puborectalis muscle and the anal sphincter is closed. During normal defecation smooth muscle relaxation of the anal canal (Sorensen, Lorentzen, Petersen, and Christiansen, 1991) occurs along with the relaxation of puborectalis muscle, straightening out the anorectal angle. In dyssynergic type of constipation, there is a paradoxical contraction of pelvic floor muscles (i.e. puborectalis muscle and external anal sphincter) leading to the significantly impaired ability to expel stool during attempts to defecate (Dailianas et al., 2000). These patients have a functional outlet obstruction related to the neuromuscular dysfunction of the defecation unit and are addressed by other names in the literature such as anismus, pelvic floor dyssynergia, obstructive defecation, paradoxical puborectalis contraction, pelvic outlet obstruction, and spastic pelvic floor or perineal syndrome. In this study, we have used the term dyssynergic defecation (DD) to refer to constipation that occurs as a result of pelvic floor dysfunction. The term functional constipation (FC) has been used where the cause of constipation could not be identified.