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Internal Anal Sphincter (internal + anal_sphincter)
Selected AbstractsCorrelation between gross anatomical topography, sectional sheet plastination, microscopic anatomy and endoanal sonography of the anal sphincter complex in human malesJOURNAL OF ANATOMY, Issue 2 2009S. Al-Ali Abstract This study elucidates the structure of the anal sphincter complex (ASC) and correlates the individual layers, namely the external anal sphincter (EAS), conjoint longitudinal muscle (CLM) and internal anal sphincter (IAS), with their ultrasonographic images. Eighteen male cadavers, with an average age of 72 years (range 62,82 years), were used in this study. Multiple methods were used including gross dissection, coronal and axial sheet plastination, different histological staining techniques and endoanal sonography. The EAS was a continuous layer but with different relations, an upper part (corresponding to the deep and superficial parts in the traditional description) and a lower (subcutaneous) part that was located distal to the IAS, and was the only muscle encircling the anal orifice below the IAS. The CLM was a fibro-fatty-muscular layer occupying the intersphincteric space and was continuous superiorly with the longitudinal muscle layer of the rectum. In its middle and lower parts it consisted of collagen and elastic fibres with fatty tissue filling the spaces between the fibrous septa. The IAS was a markedly thickened extension of the terminal circular smooth muscle layer of the rectum and it terminated proximal to the lower part of the EAS. On endoanal sonography, the EAS appeared as an irregular hyperechoic band; CLM was poorly represented by a thin irregular hyperechoic line and IAS was represented by a hypoechoic band. Data on the measurements of the thickness of the ASC layers are presented and vary between dissection and sonographic imaging. The layers of the ASC were precisely identified in situ, in sections, in isolated dissected specimens and the same structures were correlated with their sonographic appearance. The results of the measurements of ASC components in this study on male cadavers were variable, suggesting that these should be used with caution in diagnostic and management settings. [source] The pharmacology of the internal anal sphincter and new treatments of ano-rectal disordersALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 7 2001T. A. Cook Surgical options for faecal incontinence in the presence of intact sphincters are limited. Furthermore, in patients with fissures, lateral sphincterotomy reduces anal sphincter hypertonia but there has been concern about complications. A greater understanding of the basic pharmacology of the internal anal sphincter has led to the development of novel treatments for both these disorders. A Medline review was undertaken for internal anal sphincter pharmacology, anal fissures and faecal incontinence. This review is based on these articles and those found by further cross-referencing. ,Nitric oxide released from non-adrenergic non-cholinergic nerves is the main inhibitory agent in the internal anal sphincter. Relaxations are also mediated through ,-adrenoceptors and muscarinic receptors. Stimulation of ,-receptors results in contraction. Calcium and its entry through L -type calcium channels is important for the maintenance of tone. Nitric oxide donors produce reductions in resting anal tone and heal fissures but are associated with side-effects. Muscarinic agents and calcium channel antagonists show promise as low side-effect alternatives. Botulinum toxin appears more efficacious than other agents in healing fissures. To date, ,-receptor agonists have been disappointing at improving incontinence. Further understanding of the pharmacology of the internal anal sphincter may permit the development of new agents to selectively target the tissue with greater efficacy and fewer side-effects. [source] Endothelin A receptors mediate relaxation of guinea pig internal anal sphincter through cGMP pathwayNEUROGASTROENTEROLOGY & MOTILITY, Issue 9 2010S.-c. Huang Abstract Background, Endothelin (ET) modulates motility of the internal anal sphincter through unclear receptor subtypes. Methods, We measured relaxation of guinea pig internal anal sphincter strips caused by ET-related peptides and binding of 125I-ET-1 to cell membranes prepared from the internal anal sphincter muscle. Visualization of 125I-ET-1 binding sites in tissue was performed by autoradiography. Key Results , In the guinea pig internal anal sphincter, ET-1 caused a marked relaxation insensitive to tetrodotoxin, atropine, or ,-conotoxin GVIA. ET-2 was as potent as ET-1. ET-3 caused a mild relaxation. The relative potencies for ETs to cause relaxation were ET-1 = ET-2 > ET-3. The ET-1-induced relaxation was inhibited by BQ-123, an ETA antagonist, but not by BQ-788, an ETB antagonist. These indicate that ETA receptors mediate the relaxation. The relaxant response of ET-1 was attenuated by LY 83583, KT 5823, Rp-8CPT-cGMPS, tetraethyl ammonium, 4-aminopyridine and N(omega)-nitro-l-arginine, but not significantly affected by NG -nitro-l-arginine methyl ester, NG -methyl-l-arginine, charybdotoxin, apamin, KT 5720, and Rp-cAMPS. These suggest the involvement of cyclic guanosine 3,,5,-cyclic monophosphate (cGMP), and potassium channels. Autoradiography localized 125I-ET-1 binding to the internal anal sphincter. Binding of 125I-ET-1 to the cell membranes prepared from the internal anal sphincter revealed the presence of two subtypes of ET receptors, ETA and ETB receptors. Conclusions & Inferences, Taken together, these results demonstrate that ETA receptors mediate relaxation of guinea pig internal anal sphincter through the cGMP pathway. [source] Ano-rectal motility responses to pelvic, hypogastric and pudendal nerve stimulation in the Göttingen minipigNEUROGASTROENTEROLOGY & MOTILITY, Issue 2 2006I. S. Andersen Abstract, We investigated the effect of efferent stimulation of the pelvic (PN), hypogastric (HGN) and pudendal (PuN) nerves on ano-rectal motility in Göttingen minipigs using an impedance planimetry probe. Changes in the rectal cross-sectional area (CSA) at five axial positions and pressures in the rectum and anal canal were investigated simultaneously. Pelvic nerve stimulation elicited a CSA decrease in the proximal part of the rectum and a simultaneous CSA increase in its distal part. Anal pressure also decreased. Hypogastric nerve and PuN stimulation elicited an increase in anal pressure, but no rectal response. Severing the HGN produced a persistent reduction in resting anal pressure, but no change was observed when the PN and the PuN were severed. Stimulation of the distal part of all three nerves produced a persistent response. Administration of phentolamine and pancouronium eliminated the response to stimulation of the HGN and the PuN, respectively. Conclusion:, Rectal responses to PN stimulation vary more than previously suggested. The HGN has an excitatory effect on the internal anal sphincter, and the PuN on the external anal sphincter. However, the PuN plays no major role in maintaining basal anal pressure. [source] Resection of the rectum and total excision of the internal anal sphincter with smooth muscle plasty and colonic pouch for treatment of ultralow rectal carcinoma,BRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 11 2004G. I. Vorobiev Background: Intersphincteric resection can provide tumour-free margins for rectal tumours located 0,1 cm above the dentate line. However, the internal anal sphincter (IAS) is partially or totally resected and some degree of anal incontinence may develop. A novel technique of smooth muscle plasty of the IAS and colonic pouch construction is described, along with an assessment of morbidity, oncological results and functional outcome. Patients and methods: Between 1997 and 2002, 27 patients (16 men; median age 55 (range 26,75) years) were operated on for T2,3 N0,1 M0 rectal carcinoma located a median of 1·0 (range 0·5,1·5) cm from the dentate line. Resection of the IAS was performed transanally. A smooth muscle cuff, fashioned from the muscular layer of colon, and a colonic pouch were used for anorectal reconstruction. Results: There were no perioperative deaths. Anastomotic leakage developed in two patients. After a median follow-up of 38 (range 14,66) months no local recurrence was detected. Distant metastases occurred in three patients, two of whom died. Perfect functional outcome was achieved in 22 of 26 patients. At 6 months after surgery the mean(s.d.) resting anal pressure was 49(8) mmHg. Conclusion: In selected patients intersphincteric resection does not compromise the oncological result. The suggested anorectal reconstruction may improve the functional outcome. Copyright © 2004 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd. [source] Long-term effects of stapled haemorrhoidectomy on internal anal function and sensitivity,BRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 11 2001Dr D. F. Altomare Background: Stapled haemorrhoidectomy is gaining wide acceptance but there is still some concern about the risk of injury to the internal anal sphincter (IAS). IAS function and morphology, and anal canal sensitivity were studied prospectively in patients undergoing this operation. Methods: Twenty patients (11 women; mean age 43 years) with stage III haemorrhoids entered the study. All underwent preoperative anorectal manometry, rectoanal inhibitory reflex (RAIR) testing and three-dimensional transanal ultrasonography. A test of anal sensation was administered to evaluate ability to discriminate between air and warm water. All the investigations were repeated 6 months after the operation. Results: The mean(s.d.) maximal resting pressure was 87(30) mmHg before surgery and 81(20) mmHg afterwards (P not significant). The maximal squeeze pressure did not change after operation (178(43) versus 174(60) mmHg). The RAIR showed the same features in 19 of 20 patients before and 18 of 20 after operation. Three-dimensional ultrasonography demonstrated no changes in the width of the IAS (mean(s.d.) 2·1(4) mm before and 2·1(3) mm after surgery). The ability of the anal mucosa to discriminate air from warm water improved in five patients. Continence scores did not differ significantly after 6 months. Conclusion: Stapled haemorrhoidectomy does not affect the function and morphology of the IAS in the long term. The sensitivity of the anal canal can improve in patients with preoperative sensory impairment. © 2001 British Journal of Surgery Society Ltd [source] | ||||||||||