Abstract
Introduction
Normal defecation is a combination of several elements of reflex and voluntary functions. The issue of external anal sphincter innervation is of theoretical and clinical significance; however, literature on the subject is still scarce. Most study reports discuss the course of the pudendal nerve with no close insight into inferior rectal nerves supply to the external anal sphincter. We have not found any statistical “mapping” of the site of the nerve branches insertion into the external anal sphincter. Thus, the purpose of the present study was to determine the least and most typical location of nerve branches to the external anal sphincter. One hundred and ten pudendal nerve preparations were analysed. Following the dissection of the pudendal nerve and its branches, a beam compass was used to take linear measurements from the apex of the coccygeal bone to the point of nerve branch insertion to the external anal sphincter. The distance between coccygeal bone apex and the central tendon of the perineum was also measured. For the purpose of comparison, results are presented as relative Bi/A values. Computer programmes devised by the author of this paper within Turbo Pascal were then used to determine the probability of finding nerve branches to the external anal sphincter.
Results
Based on the analysis of 110 preparations of the pudendal nerve and its branches, one might conclude that the former was the main although not necessarily the only source of external anal sphincter innervation. While analysing the most and the least probable location of nerve branches to the external anal sphincter, the muscle length was expressed as percentage, i.e., 0% of sphincter length = the apex of the coccygeal bone; 100% of sphincter length = the central tendon of the perineum. The length was then divided into 5% intervals with the probability of finding nerve branches determined by programmes written in Pascal. Within 30–85% of external anal sphincter length, the probability of finding nerve branches to the external anal sphincter is greater than 0.3 with peak probability of 0.68 in the interval between 55 and 65%.
Discussion
Sphincter innervation and clinicoanatomical function of anal canal closure apparatus has been discussed with reference to external anal sphincter injury. Transcutaneous electrostimulation of the pudendal nerve and the use of anal canal electrodes have also been mentioned.
Conclusions
The most probable location of nerve branches to the external anal sphincter is half way of its length, i.e., at hour 3 or 9 of the knee-elbow position or lithotomy position. The external anal sphincter can also be directly supplied by nerve branches originating from the sacral nerve root S4; the branches then go towards the posterior part of the sphincter.
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References
Baeten CG, Konsten J, Spaans F et al (1991) Dynamic graciloplasty for treatment of faecal incontinence. Lancet 338:1163–1165
Bożiłow W, Sawicki K (1980) Metody badań zmienności cech anatomicznych człowieka podczas rozwoju prenatalnego i okołoporodowego. Akademia Medyczna we Wrocławiu, Wrocław
Delancey JOL, Toglia MR, Perucchini D (1997) Internal and external anal sphincter anatomy as it relates to midline obstetric lacerations. Obstet Gynecol 90:924–927
Eason E, Labrecque M, Wells G, Feldman P (2000) Preventing perineal trauma during childbirth: a systematic review. Obstet Gynecol 95:464–471
Engel AF, Kamm MA, Sultan AH et al (1994) Anterior anal sphincter repair in patients with obstetric trauma. Br J Surg 81:1231–1234
Falk PM, Blatchforf GJ, Cali RL, Christensen MA, Thorson AG (1994) Transanal ultrasound and manometry in the evaluation of fecal incontinence. Dis Colon Rectum 37:468–472
Fritsch H, Lienemann A, Brenner E, Ludwikowski B (2004) Clinical anatomy of the pelvic floor. Adv Anat Embryol Cell Biol 175(III–IX):1–64
Gagnard C, Godlewski G et al (1986) The nerve branches to the external anal sphincter: the macroscopic supply and microscopic structure. SRA 8:115–119
Gibbons CP, Trowbridge EA, Bannister JJ, Read NW (1988) The mechanics of the anal sphincter complex. J Biomech 21(7):601–604
Gil-Vernet S (1964) Innervation somatique et vegetative des organs genitourinaires. J Urol et Nephrol 70:45
Van der Hagen SJ, Baeten CG, Soeters PB, Gemert WG (2006) Long-term outcome following mucosal advancement flap for high perianal fistulas and fistulotomy for low perianal fistulas. Int J Colorectal Dis 21(8):784–790
Hill J, Corson RJ, Brandon H, Redford J, Faragher EB, Kiff ES (1994) History and examination in the assessment of patients with idiopathic fecal incontinence. Dis Colon Rectum 37:473–477
Jameson JS, Speakman CT, Darzi A, Chia YW, Henry MM (1994) Audit of postanal repair in the treatment of fecal incontinence. Dis Colon Rectum 37:369–372
Junginger Th, Pichlmaier H (1985) Funktionelle Anatomie des anorectalen Verschlusses. Langenbecks Archiv fur Chirurgie 366:257–261
Lunniss PJ, Phillips RK (1992) Anatomy and function of the anal longitudinal muscle. Br J Surg 79:882–884
Matzel KE, Stadelmaier U, Hohenfellner M, Gall FP (1995) Electrical stimulation of sacral spinal nerves for treatment of faecal incontinence. Lancet 28(346):1124–1127
Meyrat BJ, Vernet O, Berger D, de Tribolet N (1993) Pre- and postoperative urodynamic and anorectal manometric findings in children operated upon for a primary tethered cord. Eur J Pediatr Surg 3:309–312
Olszewski J (1973) Variations of the pudendal nerve in man. Folia Morphol 1982(2):245–252
Ostrowski K, Krassowski T, Pieńkowski M (1979) Embriologia ogólna. PZWL, Warszawa
Parks AG, Swash M, Urich H (1977) Sphincter denervation in anorectal incontinence and rectal prolapse. Gut 18:656–665
Ram E, Alper D, Stein G, Bramnik Z, Dreznik Z, (2005) Internal anal sphincter function following lateral internal sphincterotomy for anal fissurea long-term manometric study. Ann Surg doi:10.1097/01.sla.0000171036.39886.fa
Roberts WH, Taylor WH (1973) Inferior rectal nerve variations as it relates to pudendal block. Anat Rec 177:461–464
Sands D (2006) Pelvic floor dysfunction a multidisciplinary approach. pelvic floor dysfunction. doi:10.1007/1-84628-010-9_10
Setti P, Kamm MA, Nicholls RJ (1994) Long-term results of postanal repair for neurogenic faecal incotinence. Br J Surg 81:140–144
Sultan AH, Kamm MA, Hudson CN, Thomas JM, Bartram CI (1993) Anal-sphincter disruption during vaginal delivery. N Engl J Med 329:1905–1911
Tetzschner T, Sorensen M, Jonsson L et al (1997) Delivery and pudendal nerve function. Acta Obstet Gynecol Scand 76:324–331
Tjandra JJHW, Goh J, Carey M, Dwyer P (2002) Direct repair vs Overlapping sphincter repair. Dis colon rectum 46(7):937–943
Tjandra JJ, Lim F, Matzel K (2004) Sacral nerve stimulation: an emerging treatment for faecal incontinence. ANZ J Surg 74(12):1098–1106
Winckler G (1957) Les caracteristiques du nerf anal. Acta anat 30:946–952
Wunderlich M, Swash M (1983) The overlapping innervation of the two sides of the external anal sphincter by the pudendal nerves. J Neurol Sci 59:97–109
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Stefanski, L., Lampe, P. & Aleksandrowicz, R. The probability of finding nerve branches to the external anal sphincter. Surg Radiol Anat 30, 675–678 (2008). https://doi.org/10.1007/s00276-008-0379-5
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DOI: https://doi.org/10.1007/s00276-008-0379-5