1809:
423:
411:
457:
29:
324:
The IAS contributes 55% of the resting pressure of the anal canal. It is very important for bowel continence, especially for liquid and gas. When the rectum fills beyond a certain capacity, the rectal walls are distended, triggering the defecation cycle. This begins with the
69:
1829:
329:(RAIR), where the IAS relaxes. This is thought to allow a small amount of rectal contents to descend into the anal canal where specialized mucosa samples whether it is gas, liquid or solid. Problems with the IAS often present as degrees of
238:
stimulation inhibits it. It becomes relaxed in response to distention of the rectal ampulla, requiring voluntary contraction of the puborectalis and external anal sphincter to maintain continence, and also contracts during the
215:. It is about 5 mm thick, and is formed by an aggregation of the smooth (involuntary) circular muscle fibers of the rectum. It terminates distally about 6 mm from the
383:
pharmaceutical agents produce relaxation of the muscular tone of the sphincter and are applicable in pathological contexts where this tone is abnormally increased.
251:
The internal anal sphincter is the specialised thickened terminal portion of the inner circular layer of smooth muscle of the large intestine. It extends from the
538:
Sarica Y, Karacan I (July 1987). "Bulbocavernosus reflex to somatic and visceral nerve stimulation in normal subjects and in diabetics with erectile impotence".
171:
717:
399:, functional anal sphincters had been constructed in a laboratory made from muscle and nerve cells, providing a proposed solution for anal incontinence.
316:
becomes contracted to maintain continence; this transient relaxation allows passage of stool into the proximal anal canal - this filling is sensed.
1154:
784:
756:
838:
147:
693:
1092:
718:
David E. Beck, Patricia L. Roberts, Theodore J. Saclarides, Anthony J. Senagore, Michael J. Stamos, Steven D. Wexner (Editors) (2007).
727:
669:
1418:
1176:
1147:
380:
364:
259:
distally (the distal termination is palpable). Its muscle fibres are arranged in a spiral (rather than a circular) manner.
222:
The internal anal sphincter aids the sphincter ani externus to occlude the anal aperture and aids in the expulsion of the
1117:
1112:
1312:
1317:
847:
831:
514:
358:
308:
Transient relaxation of its proximal portion occurs with rectal distension and post-prandial rectal contraction (the
278:, with sympathetic innervation derived from spinal levels L1-L2, and parasympathetic innervation derived from S2-S4.
1140:
1020:
392:
235:
1492:
1132:
166:
824:
497:
Vodušek DB, Deletis V (2002). "Intraoperative
Neurophysiological Monitoring of the Sacral Nervous System".
987:
957:
351:
326:
309:
275:
781:
466:
1799:
1668:
1402:
948:
231:
178:
104:
600:
Podnar S (February 2012). "Clinical elicitation of the penilo-cavernosus reflex in circumcised men".
230:. It is normally in a state of continuous maximal contraction to prevent leakage of faeces or gases.
227:
96:
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1726:
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8:
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Jiang XZ, Zhou CK, Guo LH, Chen J, Wang HQ, Zhang DQ, et al. (December 2009). "".
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723:
675:
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613:
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555:
510:
471:
312:, respectively) while the distal portion of the sphincter remains contracted and the
1830:
Knowledge articles incorporating text from the 20th edition of Gray's
Anatomy (1918)
629:
524:
410:
1625:
1615:
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289:(which provides motor and sensory innervation to the external anal sphincter).
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stimulation also produces relaxation which has pharmacological significance.
208:
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1221:
659:
621:
586:
256:
114:
42:
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559:
487:
Moore, K., Dalley, A., Agur, A. "Clinically
Oriented Anatomy. 6th Edition.
1701:
1638:
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1469:
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1168:
791:, Wake Forest School of Medicine. December 12, 2015. Retrieved 3 feb 2017
444:
54:
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stimulation stimulates and maintains the sphincter's contraction, and
1771:
1761:
1263:
262:
At its distal extremity, it is in contact with but separate from the
1484:
859:
851:
770:"Human cells engineered to make functional anal sphincters in lab"
1522:
1344:
1301:
1185:
1058:
Deep perineal fascia / superficial investing fascia (Gallaudet's)
499:
Neurophysiology in
Neurosurgery, A Modern Intraoperative Approach
807:
at The
Anatomy Lesson by Wesley Norman (Georgetown University) (
1660:
1010:
298:
274:
The sphincter receives extrinsic autonomic innervation via the
74:
50:
1579:
1538:
223:
130:
118:
91:
216:
68:
28:
16:
Ring of smooth muscle that surrounds part of the anal canal
661:
Gray's
Anatomy: The Anatomical Basis of Clinical Practice
772:, Science Daily. August 10, 2011. Retrieved 3 feb 2017
333:(especially partial incontinence to liquid) or mucous
297:
The sphincter is contracted in its resting state, but
1797:
301:relaxes in certain contexts (most notably during
1821:
572:
310:recto-anal inhibitory reflex and sampling reflex
99:(S4), thoracicolumbar outflow of the spinal cord
720:The ASCRS textbook of colon and rectal surgery
496:
1148:
832:
537:
354:and results in contraction of the sphincter.
876:
361:and results in relaxation of the sphincter.
211:that surrounds about 2.5–4.0 cm of the
490:
357:Parasympathetic stimulation is mediated by
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1141:
839:
825:
593:
531:
67:
27:
755:CS1 maint: multiple names: authors list (
657:
566:
664:(42th ed.). New York. p. 683.
386:
375:
370:
846:
694:"Chapter 36: The rectum and anal canal"
350:Sympathetic stimulation is mediated by
1822:
653:
651:
649:
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645:
643:
641:
639:
599:
461:This article incorporates text in the
1136:
820:
117:closed, aids in the expulsion of the
57:. I.S. Internal anal sphincter. E.S.
402:
1088:Inferior fascia (Perineal membrane)
636:
255:proximally to just proximal to the
253:pectinate line (anorectal junction)
13:
359:muscarinic acetylcholine receptors
345:
14:
1851:
1067:Deep fascia of the penis (Buck's)
798:
391:In 2011, it was announced by the
1807:
614:10.1111/j.1464-410X.2011.10364.x
507:10.1016/B978-012209036-3/50011-1
455:
421:
409:
958:Superficial transverse perineal
775:
281:The internal anal sphincter is
136:musculus sphincter ani internus
763:
711:
686:
481:
393:Wake Forest School of Medicine
269:
1:
552:10.1016/S0022-5347(17)42987-9
450:
340:
319:
352:alpha-2 adrenergic receptors
246:
33:Coronal section through the
7:
1403:Enterochromaffin-like cells
1021:Superficial perineal fascia
469:of the 20th edition of
433:
327:rectoanal inhibitory reflex
292:
276:inferior hypogastric plexus
10:
1856:
949:Superficial perineal pouch
179:Anatomical terms of muscle
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658:Standring, Susan (1201).
428:Anatomy of the human anus
226:. Its action is entirely
177:
165:
153:
141:
129:
124:
103:
90:
85:
66:
26:
21:
988:Deep transverse perineal
97:Pelvic splanchnic nerves
53:. A.C. Anal canal. L.A.
1727:External anal sphincter
1722:Intersphincteric groove
1717:Internal anal sphincter
1234:Pterygomandibular raphe
440:External anal sphincter
314:external anal sphincter
264:external anal sphincter
197:internal anal sphincter
59:External anal sphincter
22:Internal anal sphincter
1508:Duodenojejunal flexure
1503:Minor duodenal papilla
1498:Major duodenal papilla
1249:Pharyngobasilar fascia
1244:Buccopharyngeal fascia
1165:gastrointestinal tract
722:. New York: Springer.
575:Zhonghua Yi Xue Za Zhi
540:The Journal of Urology
241:bulbospongiosus reflex
205:sphincter ani internus
1465:Enteroendocrine cells
1036:in scrotum and penis:
387:Regenerative medicine
376:Clinical pharmacology
371:Clinical significance
1079:Urogenital diaphragm
1050:Deep perineal fascia
49:. R. Second part of
1398:Gastric chief cells
993:Urethral sphincters
979:Deep perineal pouch
939:Urogenital triangle
73:Coronal section of
787:2018-05-23 at the
748:has generic name (
331:fecal incontinence
285:innervated by the
1795:
1794:
1787:Muscularis mucosa
1739:
1738:
1735:
1734:
1649:epiploic appendix
1565:
1564:
1493:Suspensory muscle
1455:Intestinal glands
1413:
1412:
1130:
1129:
1126:
1125:
1065:
1037:
1005:
1004:
1001:
1000:
917:
916:
782:"Anal Sphincters"
729:978-0-387-24846-2
671:978-0-7020-7707-4
602:BJU International
581:(46): 3249–3252.
403:Additional images
193:
192:
188:
1847:
1812:
1811:
1803:
1669:Transverse folds
1626:Descending colon
1616:Transverse colon
1576:
1575:
1530:No substructures
1513:Brunner's glands
1443:Intestinal villi
1433:
1432:
1424:
1423:
1323:Angular incisure
1239:Pharyngeal raphe
1207:retropharyngeal
1182:
1181:
1167:, excluding the
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1134:
1133:
1106:
1104:Pelvic diaphragm
1081:
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1035:
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1016:
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968:Ischiocavernosus
951:
944:
943:
904:Ischioanal fossa
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696:. Archived from
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335:rectal discharge
185:edit on Wikidata
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1621:Splenic flexure
1611:Hepatic flexure
1606:Ascending colon
1592:
1571:Large intestine
1561:
1557:Microfold cells
1552:Peyer's patches
1547:Ileocecal valve
1533:
1517:
1479:
1428:Small intestine
1409:
1296:
1258:
1212:parapharyngeal
1202:peripharyngeal
1171:
1163:Anatomy of the
1161:
1131:
1122:
1118:Superior fascia
1113:Inferior fascia
1102:
1097:
1093:Superior fascia
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1072:
1049:
1044:
1019:
997:
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963:Bulbospongiosus
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789:Wayback Machine
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346:Neurophysiology
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236:parasympathetic
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47:Seminal vesicle
39:urinary bladder
37:. B. Cavity of
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1777:Circular folds
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1767:Muscular layer
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1393:Parietal cells
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1388:Foveolar cells
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1383:Pyloric glands
1380:
1375:
1373:Cardiac glands
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1368:Gastric glands
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1350:Gastric mucosa
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608:(4): 582–585.
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577:(in Chinese).
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1378:Fundic glands
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1359:Microanatomy
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1355:Gastric folds
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1039:Dartos fascia
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1475:Paneth cells
1470:Goblet cells
1436:Microanatomy
1363:Gastric pits
1227:prevertebral
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43:Vas deferens
1702:Anal valves
1639:taenia coli
1635:Continuous
1460:Enterocytes
1309:Curvatures
1271:Sphincters
501:: 153–165.
445:Levator ani
299:reflexively
270:Innervation
232:Sympathetic
228:involuntary
125:Identifiers
55:Levator ani
1824:Categories
1757:Adventitia
1684:Anal canal
1448:Microvilli
704:2011-07-12
680:1201341621
451:References
416:Intestines
341:Physiology
320:Continence
303:defecation
213:anal canal
111:anal canal
109:Keeps the
79:anal canal
35:anal canal
1772:Submucosa
1762:Subserosa
1264:Esophagus
1064:in penis:
738:cite book
381:Nitrergic
365:Nitrergic
247:Structure
219:orifice.
1835:Perineum
1588:Appendix
1485:Duodenum
891:Internal
886:External
860:Perineum
852:perineum
785:Archived
630:27143105
622:21883821
587:20193361
525:78605592
467:page 426
434:See also
293:Function
1814:Anatomy
1674:Ampulla
1644:haustra
1523:Jejunum
1345:Pylorus
1313:greater
1302:Stomach
1198:Spaces
1194:Muscles
1186:Pharynx
848:Muscles
560:3599220
115:orifice
105:Actions
86:Details
45:. S.V.
1800:Portal
1782:Mucosa
1753:Serosa
1661:Rectum
1340:Fundus
1330:Cardia
1318:lesser
1287:glands
1222:danger
1011:Fascia
922:Middle
810:Rectum
805:Pelvis
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75:rectum
51:rectum
1598:Colon
1580:Cecum
1539:Ileum
1419:Lower
1280:lower
1275:upper
1177:Upper
1169:mouth
626:S2CID
521:S2CID
465:from
224:feces
203:, or
183:[
172:15710
131:Latin
119:feces
92:Nerve
41:V.D.
1840:Anus
1745:Wall
1692:Anus
1335:Body
1292:crop
757:link
750:help
724:ISBN
676:OCLC
666:ISBN
618:PMID
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556:PMID
511:ISBN
217:anal
195:The
160:3018
143:TA98
113:and
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283:not
201:IAS
167:FMA
155:TA2
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Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
