Abstract
PURPOSE: The possible existence of an anatomic and functional separation between the external sphincter and the puborectalis muscle has been reported in the medical literature. In this article we confirm, by means of anatomic and clinical observations, the presence of such a separation, focusing on its importance in understanding the pathway of diffusion for some suppurative anal lesions and to plan advanced sphincter-sparing procedures. METHODS: Twenty adult anatomic specimens of the anal region (12 from women) were cut in the sagittal, coronal, and paracoronal planes, stained with hematoxylin and eosin, and examined. The pelvic floor musculature was examined in three patients undergoing postanal repair operations. Thirty primary posterior and posterolateral anal fistulas, preoperatively classified as transsphincteric (22) or suprasphincteric (8) were carefully traced during and after staged fistulotomy in 30 (11 female) patients, and their relationship with puborectalis muscle and external sphincter was evaluated. An attempt was made peranally to separate the external sphincter from the puborectalis muscle in four patients (3 females) aged 56 to 65 years with rectal cancers 4 to 5 cm from the anal verge so as to perform a sphincter-sparing procedure. RESULTS: A connective plane of separation between puborectalis muscle and external sphincter was clearly identified in 14 (70 percent) anatomic specimens. In three (21 percent) cases the two muscles presented a pronounced overlapping arrangement. An anatomicofunctional separation between puborectalis muscle and external sphincter was easily demonstrated during postanal repair operations. All fistulous tracks ran between the external sphincter and puborectalis muscle, despite the pronounced upward direction of the ones preoperatively classified as suprasphincteric. A plane of separation between puborectalis muscle and external sphincter was identified and developed in four patients with very low rectal cancers. An abdominoperanal rectolevatorial excision was performed. A coloanal anastomosis was performed on the residual lower anal canal. CONCLUSION: An anatomic plane of separation is present between the puborectalis muscle and the external sphincter. The presence of this plane is important to help understand the diffusion of some suppurative anal lesions and to plan advanced sphincter-sparing procedures.
Similar content being viewed by others
References
Percy JP, Neill ME, Swash M, Parks AG. Electrophysiological study of motor nerve supply of pelvic floor. Lancet 1981;1:16–7.
Matzel KE, Schmidt RA, Tanagho EA. Neuroanatomy of the striated muscular anal continence mechanism: implication for the use of neurostimulation. Dis Colon Rectum 1990;33:666–73.
Levi AC, Borghi F, Garavoglia M. Development of anal canal muscles. Dis Colon Rectum 1991;34:262–6.
Fucini C, Messerini L, Giacomobono R, Masi A, Cionini L, Elbetti C. Excision of the levators in a sphincter sparing operation for rectal cancer. Coloproctology 1993;5:284–8.
Fucini C. One stage treatment of anal abscesses and fistulas. Int J Colorectal Dis 1991;6:12–6.
Parks AG. Postanal perineorrhaphy for rectal prolapse. Proc R Soc Med 1967;60:44–5.
Milligan ET., Morgan CN. Surgical anatomy of the anal canal. Lancet 1934;2:1150–6, 1213–7.
Oh C, Kark AE. Anatomy of the external anal sphincter. Br J Surg 1972;59:717–23.
Parks AG, Gordon PH, Hardcastle JD. A classification of fistula in ano. Br J Surg 1976;63:1–12.
Rowe JS, Skandalakis JE, Gray SW, Olafson RP, Steinman RJ. The surgical anal canal. Contemp Surg 1974;5:107–17.
Lawson JO. Pelvic anatomy. II: Anal canal and associated sphincters. Ann R Coll Surg Engl 1974;54:288–300.
Holl M. Uber den Verschluss des Mannlichen Beckeus. Archiv fur Anatomie und Physiologie Leipzig, Anat Act 1881:225–71.
Popowsky J. Zur Entwickelungsgeschichte der Dammuskulatur beim Menschen. Anat Heft 1899;12:15–48.
Thompson P. The myology of the pelvic floor: a contribution to human and comparative anatomy. London: Newton/McCorquodale, 1899.
Johnson FP. The development of the rectum in the human embryo. Am J Anat 1914;16:1–57.
Courtney H. Anatomy of the pelvic diaphragm and anorectal musculature as related to sphincter preservation in ano-rectal surgery. Am J Surg 1950;79:155–73.
Goligher JC, Leacock AG, Brossy JJ. The surgical anatomy of the anal canal Br J Surg 1955;43:51–61.
Wendell-Smith CP. The homologues of the puborectalis muscle. J Anat 1964;98:489.
Lawson JO. Pelvic anatomy. I: Pelvic floor muscles. Ann R Coll Surg Engl 1974;54:244–52.
DeVries PA, Friedland GW. The staged sequential development of the anus and rectum in human embryos and fetuses. J Pediatr Surg 1974;9:755–69.
Ayoub SF. Anatomy of the external sphincter in man. Acta Anat 1979;105:25–36.
Eisenhammer S. The final evaluation and classification of surgical treatment of the primary anorectal cryptoglandular intermuscular (intersphincteric) fistulous abscess and fistula. Dis Colon Rectum 1978;21:237–54.
Seow-Choen F, Phillips RK. Insights gained from management of problematic anal fistulae at St. Mark's Hospital, 1984–88. Br J Surg 1991;78:539–41.
Van Tets WF, Kuijpers HC. Continence disorders after anal fistulotomy. Dis Colon Rectum 1994;37:1194–7.
Aguilar PS, Plasencia G, Hardy TG Jr, Hartmann RF, Stewart WR. Mucosal advancement in the treatment of anal fistula. Dis Colon Rectum 1985;28:496–8.
Stone JM, Goldberg SM. The endorectal advancement flap procedure. Int J Colorectal Dis 1990;5:232–5.
Author information
Authors and Affiliations
About this article
Cite this article
Fucini, C., Elbetti, C. & Messerini, L. Anatomic plane of separation between external anal sphincter and puborectalis muscle. Dis Colon Rectum 42, 374–379 (1999). https://doi.org/10.1007/BF02236356
Issue Date:
DOI: https://doi.org/10.1007/BF02236356