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10 A. Bondurri
Culp CE (1983) Chronic hidradenitis of the anal canal: a surgical skin disease. Dis Colon Rectum
26:669–676
Devaraj B, Khabassi S, Cosman BC (2011) Recent smoking is a risk factor for anal abscess and
fistula. Dis Colon Rectum 54(6):681–685
El-Tawil AM (2012) Mechanism of non-specific-fistula-in-ano: hormonal aspects – review. Path-
ophysiology 19(1):55–59
Felt-Bersma RJ, Bartelsman JF (2009) Haemorrhoids, rectal prolapse, anal fissure, peri-anal fistulae
and sexually transmitted diseases. Best Pract Res Clin Gastroenterol 23:575–592. [PMID:
19647691. https://doi.org/10.1016/j.bpg.2009.04.010
Fugita FR, Marques dos Santos CH, Otávio da Silva Ribeiro C (2020) Epidemiological profile of
patients with fistula in ano. J Coloproctol. (Rio J.). 40:1–7
García-Olmo D, Van Assche G, Tagarro I, Carmen Diez M, Richard MP, Khalid JM (2018) The
prevalence of perianal fistulas in Europe: estimate from literature review and from a United
Kingdom population-based database analysis. In: ESCP, Nice, France
Goligher JC, Ellis M, Pissidis AG (1967) A critique of anal glandular infection in the aetiology and
treatment of idiopathic anorectal abscesses and fistulas. Br J Surg 54:977–983
Gupta PJ (2005) Ano-perianal tuberculosis–solving a clinical dilemma. Afr Health Sci 5:345–347
Győry H (2008) Surgery in ancient Egypt. In: Selin H (ed) Encyclopaedia of the history of science,
technology, and medicine in non-western cultures. Springer, Dordrecht
Hamadani A, Haigh PI, Liu IL et al (2009) Who is at risk for developing chronic anal fistula or
recurrent anal sepsis after initial perianal abscess? Dis Colon Rectum 52(2):217–221
Hokkanen SRK (2019) Prevalence of anal fistula in the United Kingdom. World J Clin Cases 7(14):
1795–1804
Homsi R, Daikoku NH, Littlejohn J, Wheeless CR Jr (1994) Episiotomy: risks of dehiscence and
rectovaginal fistula. Obstet Gynecol Surv 49:803–808
Jamshidi R (2018) Anorectal complaints: hemorrhoids, fissures, abscesses, fistulae. Clin Colon
Rectal Surg 31(2):117–120. https://doi.org/10.1055/s-0037-1609026. Epub 2018 Feb 25
Lillius HG (1968) An investigation on human foetal anal ducts and intramuscular glands: a clinical
study of 150 patients. Acta Chir Scand 383:7–88
Lunniss PJ, Phillips RKS (1994) Surgical assessment of acute anorectal sepsis is a better predictor
of fistula than microbiological analysis. Br J Surg 81:368–369
Malik AI, Nelson RL (2008) Surgical management of anal fistulae: a systematic review. Color Dis
10:420–430
Marks CG, Ritchie JK, Lockhart-Mummery HE (1981) Anal fistulas in Crohn’s disease. Br J Surg
68:525–527
McColl I (1967) The comparative anatomy and pathology of anal glands. Arris and Gale lecture
delivered at the Royal College of Surgeons of England on 25th February 1965. Ann R Coll Surg
Engl 40(1):36–67
Molendijk I, Nuij VJ, van der Meulen-de Jong AE et al (2014) Disappointing durable remission
rates in complex Crohn’s disease fistula. Inflamm Bowel Dis 20:2022–2028
Nelson RL, Abcarian H (1996) Do hemorrhoids cure cancer? Sem Colon Rectal Surg 6:178–181
Nelson RL, Abcarian H (2014) Epidemiology, incidence and prevalence of fistula in Ano. In:
Abcarian H (ed) Anal fistula. Principles and management. Springer, New York
Onaca N, Hirshberg A, Adar R (2001) Early reoperation for perirectal abscess: a preventable
complication. Dis Colon Rectum 44(10):1469–1473
Pakarinen MP, Rintala RJ, Koivusalo A (2020) Disorders of anus and rectum. In: Puri P
(ed) Pediatric surgery. Springer, Berlin/Heidelberg
Parés D (2011) Pathogenesis and treatment of fistula in ano. Br J Surg 98(1):2–3
Parks AG (1961) Pathogenesis and treatment of fistula-in-ano. Br Med J 18:463–469
Parks AG, Gordon PH, Hardcastle JD (1976) A classification of fistula-inano. Br J Surg 63(1):1–12
Pearce L, Newton K, Smith SR et al (2016) Multicentre observational study of outcomes after
drainage of acute perianal abscess. Br J Surg 103(8):1063–1068
Phillips RKS, Clark S (2014) Colorectal surgery. Companion to specialist surgical practice, 5th edn.
Saunders/Elsevier, Edinburgh
1 Epidemiology of Anal Fistula and Abscess 11
Pinto RA, Peterson TV, Shawki S, Davila GW, Wexner SD (2010) Are there predictors of outcome
following rectovaginal fistula repair? Dis Colon Rectum 53:1240–1247
Radcliffe AG, Ritchie JK, Hawley PR, Lennard-Jones JE, Northover JM (1988) Anovaginal and
rectovaginal fistulas in Crohn’s disease. Dis Colon Rectum 31:94–99
Ramanujam PS, Prasad ML, Abcarian H, Tan AB (1984) Perianal abscesses and fistulas. A study of
1023 patients. Dis Colon Rectum 27(9):593–597
Rankin GB, Watts HD, Melnyk CS, Kelley ML (1979) National Cooperative Crohn’s Disease
Study: extraintestinal manifestations and perianal complications. Gastroenterology 77:914–920.
[PMID: 467943]
Read DR, Abcarian H (1979) A prospective survey of 474 patients with anorectal abscess. Dis
Colon Rectum 22(8):566–568
Saclarides TJ (2002) Rectovaginal fistula. Surg Clin North Am 82:1261–1272
Sahnan K, Askari A, Adegbola SO, Tozer PJ, Phillops RKS, Hart A, Faiz OD (2017) Natural
history of anorectal sepsis. Br J Surg 104:1857–1863
Sainio P (1984) Fistula-in-ano in a defined population. Incidence and epidemiological aspects. Ann
Chir Gynaecol 356:219–224. pmid:6508203
Sankaran PS (1976) Sushruta’s contribution to surgery. Varanasi Ideological Book House
Schwartz DA, Loftus EV, Tremaine WJ, Panaccione R, Harmsen WS, Zinsmeister AR, Sandborn
WJ (2002) The natural history of fistulizing Crohn’s disease in Olmsted County, Minnesota.
Gastroenterology 122:875–880. https://doi.org/10.1053/gast.2002.32362. PMID: 11910338
Scieux C, Barnes R, Bianchi A, Casin I, Morel P, Perol Y (1989) Lymphogranuloma Venereum:
27 cases in Paris. J Infect Dis 160:662–668
Seow-Choen F, Hay AJ, Heard S, Phillips RK (1992) Bacteriology of anal fistulae. Br J Surg 79(1):
27–28
Shukla HS, Gupta SC, Singh G, Singh PA (1988) Tubercular fistula in ano. Br J Surg 75:38–39
Sneider EB, Maykel JA (2013) Anal abscess and fistula. Gastroenterol Clin N Am 42(4):773–784
Sozener U, Gedik E, Kessaf Aslar A, Ergun H, Halil Elhan A, Memikoğlu O, Bulent Erkek A,
Ayhan Kuzu M (2011) Does adjuvant antibiotic treatment after drainage of anorectal abscess
prevent development of anal fistulas? A randomized, placebo-controlled, double-blind, multicenter study. Dis Colon Rectum 54(8):923–9
Stanton C, Holtz SA, Ahmed S (2007) Challenges in measuring obstetric fistula. Int J Gynaecol
Obstet 99(Suppl 1):S4–S9
Sugrue J (2017) Pathogenesis and persistence of cryptoglandular anal fistula: a systematic review.
TIC 21(6):425–432
Tebeu et al (2012) Risk factors for obstetric fistula: a clinical review. Int Urogynecol J 23(4):387–
394
Tozer PJ, Rayment N, Hart AL, Daulatzai N, Murugananthan AU, Whelan K, Phillips RK (2015)
What role do bacteria play in persisting fi stula formation in idiopathic and Crohn’s anal fistula?
Color Dis 17(3):235–241
Venkatesh KS, Ramanujam PS, Larson DM, Haywood MA (1989) Anorectal complications of
vaginal delivery. Dis Colon Rectum 32:1039–1041
Vogel JD, Johnson EK, Morris AM et al (2016) Clinical practice guideline for the management of
anorectal abscess, fistula-in-ano, and rectovaginal fistula. Dis Colon Rectum 59(12):1117–1133
Wang D, Yang G, Qiu J, Song Y, Wang L, Gao J, Wang C (2014) Risk factors for anal fistula: a case-
control study. Tech Coloproctol 18(7):635–639
Williams JG, Farrands PA, Williams AB et al (2007) The treatment of anal fistula: ACPGBI position
statement. Color Dis 9:18–50
Wright WF (2016) Infectious diseases perspective of anorectal abscess and fistula-in-ano disease.
Am J Med Sci 351:427–434
Xu RW, Tan K-K (2016) Bacteriological study in perianal abscess is not useful and not cost-
effective. ANZ J Surg 86:420–421
Zanotti C, Martinez-Puente C, Pascual I, Pascual M, Herreros D, García-Olmo D (2007) An
assessment of the incidence of fistula-in-ano in four countries of the European Union. Int J
Color Dis 22:1459–1462
Anorectal Anatomy Related to Anal Fistula and Abscess
Kirsty R. Cattle and Toby M. Hammond
Contents
1 Introduction .................................................................................. 14
2 Mucosal Layer and Submucosal Space ................................... .................. 14
3 Internal Anal Sphincter . . . ................................................................... 15
4 Intersphincteric Space and Conjoint Longitudinal Muscle ... . ....................... ...... 15
5 External Anal Sphincter . . . ...... . ................. .......................................... 16
6 Pelvic Floor .................................................................. ................ 16
7 Extra-anal Spaces/Ischioanal Fossae ........................................................ 19
8 Anal Glands ..... .................................... .................................... .... 19
9 Relationship of Anatomy to Pathogenesis, Classification, and Management ... . .......... 20
10 Conclusion ................................................................................... 22
11 Cross-References ...... ......................................................... ............. 23
References .................... ................................ ................................ .... 23
2
Abstract
The anal canal is the most distal part of the gastrointestinal tract, beginning where
the rectum narrows down to pass through the pelvic floor and ending at the anal
verge. The anal canal is encircled by the anal sphincter complex, which is composed of four concentric rings, and their associated spaces. From the inner to the
outermostlayers, they consist of a mucosal layer, the submucosal space, the internal
anal sphincter, the intersphincteric space within which lies the conjoint longitudinal
muscle, and finally, the external anal sphincter. Fibers of the conjoint longitudinal
muscle spread down the intersphincteric space and traverse both the internal and
external sphincters. The anal sphincter complex is supported by passive connective
tissue layers and active muscular layers of the pelvic floor. It is surrounded by a
layer of adipose tissue that sits within the ischioanal fossae. Mucin secreting anal
glands sit within the submucosal and intersphincteric spaces. This arrangement is
central to understanding the etiology of perianal sepsis and fistulas.
K. R. Cattle · T. M. Hammond (*)
Mid and South Essex Hospitals NHS Foundation Trust, Chelmsford, UK
e-mail: kirstymcdowell@doctors.org.uk; Toby.Hammond@meht.nhs.uk
© Springer Nature Switzerland AG 2022
C. Ratto et al. (eds.), Anal Fistula and Abscess, Coloproctology,
https://doi.org/10.1007/978-3-030-76670-2_2
13
14 K. R. Cattle and T. M. Hammond
Keywords
Anal canal · Anal glands · Anal sphincters · Pelvic floor
1 Introduction
The anal canal is the most distal part of the gastrointestinal tract, extending from the
anorectal ring and traversing the pelvic floor to open at the anus. It measures about
4 cm in length, but this is variable between the sexes and between individuals.
Whereas the rectum passes antero-caudally, the anal canal passes postero-caudally,
there being an angle at the anorectal junction (see Fig. 1), which is important in the
maintenance of continence.
2 Mucosal Layer and Submucosal Space
The innermost layer of the anal canal is the mucosa. Caudally it is made of stratified
squamous epithelium, its cranial extent demarcated by an area known as the dentate
line. At this juncture the mucosa changes to the stratified cuboidal epithelium and
variably extends for a distance approximating 1 cm – the anal transition zone.
Thereafter, passing in a cranial direction, the mucosa comprises columnar epithelium.
Deep to the mucosal layer lies the submucosal space. This contains connective
tissue, vasculature, and the muscularis mucosae.
The anal mucosa and submucosa are thrown into 6–10 vertical folds, known as
anal columns (of Morgagni). These contain terminal branches of the superior rectal
artery and vein. Three of these columns are more prominent and form vascular anal
Fig. 1 Sagittal section of the pelvis, concentrating on the anus and rectum, showing the anorectal
angle and relationships of the anorectum to the pelvic organs and pelvic floor
2 Anorectal Anatomy Related to Anal Fistula and Abscess 15
cushions, which add to the maintenance of continence, but if pathologically enlarged
are called hemorrhoids. These columns end at crescent-shaped folds, the “anal
valves,” between which sit small depressions, the “anal sinuses.” These valves and
sinuses form the “saw-toothed” dentate line. The muscularis mucosae of the rectum
continues caudally within the submucosal space and is contributed to by fibers from
the longitudinal muscle of the rectum (see below), which cross the internal anal
sphincter from the intersphincteric space. These muscle fibers attach firmly to the
mucosa at the dentate line, forming the mucosal suspensory ligament of Parks, also
known as Trietz’s muscle (Standring 2016a; Zoulamoglou et al. 2017).
3 Internal Anal Sphincter
Lateral to the submucosal space, the thickened caudal continuation of the circular
smooth muscle of the rectal wall forms the internal anal sphincter. It receives
autonomic innervation and is columnar in shape. It extends for approximately
2.5 cm in length from the anorectal junction to a variable distance above the
lowermost extent of the external anal sphincter, with a well-defi ned border. It is
thicker in males than females and increases in thickness with age, due to an
accumulation of connective tissue (Kumar and Emmanuel 2017).
Histologically, the internal anal sphincter is clearly different from the rectal
smooth muscle and can be seen to have two parts. Cranially, the muscle fibers are
arranged in ovoid bundles, which slope inferomedially. This part receives muscle
fibers from the longitudinal muscle of the rectal wall, in contrast to the caudal part.
Caudally, fibers from puborectalis and the anterior sacrococcygeal ligament pass
through the internal anal sphincter to insert into the anal skin, contributing to the
mucosal suspensory ligament. Initially, the muscle fibers within the caudal part lie
transversely, before lying superomedially (Lawson 1974b).
The internal sphincter has attachments to both the perianal skin and the fascia of
the pelvic floor, allowing anchoring of the sphincter complex and aiding its action.
Fibers also pass toward the perianal skin, passing through the muscularis mucosae.
Anteriorly there are attachments to the perineal body (Lawson 1974b).
4 Intersphincteric Space and Conjoint Longitudinal Muscle
The conjoint longitudinal muscle of the anal canal is a continuation of the longitudinal
muscle of the rectum, lying between the internal and external anal sphincters within
the intersphincteric space. It is composed of smooth muscle augmented with striated
muscle from a variety of debated sources, including the levator ani, puborectalis, and
pubococcygeus muscles of the pelvic floor. As it passes caudally within the
intersphincteric space, fibers branch out in three directions. A proportion of fibers
traverse the internal anal sphincter to join with the muscularis mucosae of the
submucosal space contributing to the mucosal suspensory ligament. Some fibers
pass through and around the external anal sphincter to blend with the fat of the
16 K. R. Cattle and T. M. Hammond
ischioanal fossa. However, the majority of fibers pass down the intersphincteric space,
around and through the lowermost fibers of the subcutaneous part of the external anal
sphincter to insert into the perianalskin, terminating at the junction between the dermis
and epidermis (Lunniss and Phillips 1992). The branching fibers of the conjoint
longitudinal muscle form a complex supporting meshwork of septa that anchors the
sphincter complex in place.
5 External Anal Sphincter
The external anal sphincter consists of skeletal, striated muscle fibers, predominantly
of fatigue-resistant type I fibers (Beersi ek et al. 1979). Hi storically, it was described
as consisting of three parts – deep, superficial, and subcutaneous (Ayoub 1979;
Milligan et al. 1937), but more recent anatomical studies show the sphincter as one
whole muscle mass (see Figs. 4 and 5). The nature of this muscle differs cranially
and caudally. The deeper more cranial part is intimately associated with the levator
ani of the pelvic floor musculature. It surrounds the internal anal sphincter and the
conjoint longitudinal muscle. The more superficial caudal part of the external anal
sphincter turns inwards to terminate subcutaneously below the caudal limit of the
internal anal sphincter. There is no plane of division between the two parts of the
external anal sphincter (Ayoub 1979; Fritsch et al. 2002; Goligher et al. 1955).
Anteriorly, muscle fibers of the external anal sphincter cross the midline and fuse
with fibers of the transverse perinei muscles (Ayoub 1979). Muscle fibers also enter
the perineal body (Lawson 1974b). Posteriorly, fibers of the external anal sphincter
become tendinous in nature and enter the anococcygeal ligament, anchoring the anal
canal to the coccyx and natal cleft (Ayoub 1979).
In males, the external anal sphincter is cylindrical, whereas in females it is wedge
shaped, being shorter anteriorly than posteriorly. When imaged, this can appear as
though the superior portion of the external anal sphincter is deficient anteriorly, but
this is the normal appearance in the female and should not be confused with a partial
sphincter injury (Sultan et al. 1994). This anatomical difference can be one of the
determinants in the surgical management of idiopathic anal fistulas.
6 Pelvic Floor
As the anal canal passes through and is supported by the muscles of the pelvic floor,
a detailed discussion of its anatomy is of fundamental importance. There are two
layers of muscles, the true pelvic floor muscles and the perineal muscles, supported
and stiffened by fascial planes.
The fascia of the pelvic floor provides passive support. The endopelvic fascia is
the most cranial layer and is a continuous sheet covering the levator ani muscles and
pelvic organs. Parts of this loose aggregation of collagen, smooth muscle, and elastin
are more densely organized and support the uterus via the uterosacral and cardinal
ligaments (Strohbehn 1998). Laterally within the pelvis, the connective tissue is
2 Anorectal Anatomy Related to Anal Fistula and Abscess 17
organized into two dense ligament-type structures, consisting mainly of fibrous
collagen. These are the arcus tendineus fasciae pelvis (ATFP) and arcus tendineus
levator ani (ATLA, see Fig. 2). The ATFP attaches to the pubic ramus and ischial
tuberosity, providing support at the lateral edges of the anterior vaginal wall. Thus the
anterior vaginal wall acts as a hammock to support the urethra and bladder. The ATLA
lies lateral to the ATFP, also attaching to the pubic rami and ischial tuberosities. It
provides muscular attachment for the levator ani muscles, which support the rectum
and anus in a similar manner to the vaginal support of the bladder (Strohbehn 1998).
Caudal to the pelvic floor muscles, a layer of dense connective tissue separates the
levator ani muscles from the superficial perineal muscles. This is the perineal
membrane, which in the male is a single triangular sheet running between the
ischiopubic rami. In the female, it is divided by the urethra and vagina and is less
well defined. The transverse perineal artery runs in its posterior edge to supply the
perineal body (Wendell Smith and Wilson 1970).
Fig. 2 A caudal view of the pelvic floor muscles and related connective tissue supports. (Reprinted
from An Atlas of Human Anatomy, B Anson, p 366, published by WB Saunders, copyright Elsevier
1950)
18 K. R. Cattle and T. M. Hammond
Within the center of the perineum lies the perineal body, a dense fibromuscular
mass measuring about 1.5–2 cm wide by 1–1.5 cm in the anteroposterior direction
and 2–2.5 cm in the craniocaudal direction in the male, although it is much wider and
thicker in the female. It attaches to the deep and superficial fascial coverings, the
levator ani, transverse perinei muscles, and the external anal sphincter, anchoring
and supporting the anal canal (Oh and Kark 1973).
The pelvic floor muscles, known collectively as levator ani, consist of muscles
which support the pelvic organs and true diaphragmatic muscles. The levator ani
muscles are divided into different parts, depending on their attachments, but act
together to support and lift the pelvic organs. They consist of iliococcygeus laterally
and the pubovisceral muscles medially. Iliococcygeus is sheet-like and attaches to
the pubic bone and the arcus tendineus levator ani anterolaterally and to the coccyx
and midline raphe posteromedially, forming a diaphragm to support the pelvic
organs (Fig. 2). The pubovisceral muscle, sometimes called pubococcygeus, is
sling-like, arising from the pubis anteriorly and looping around each of the pelvic
organs. Different slips of pubococcygeus are attached to and pass around the urethra,
vagina, and rectum, being named pubourethralis, pubovaginalis, and puborectalis,
respectively, lifting the pelvic floor and maintaining continence (Lawson 1974a).
The superficial perineal muscles (see Fig. 3) comprise bulbospongiosus, ischiocavernosus, and transverse perinei. Bulbospongiosus muscles are attached to the
ab
Ischiocavernosus
Bulbospongiosus
Superficial
transverse
perineal
Subcutaneous
Superficial
c
External
sphincter
ani
Sphincter urethrea
Compressor urethrae
Sphincter
urethrovaginalis
Smooth
muscle
Deep external
sphincter ani
Crus clitoridis
Vestibular bulb
Perineal
membrane
Greater
vestibular
gland
Puborectalis
Fig. 3 Three levels of the perineum from superficial to deep. (a) The superficial muscles. (b) The
perineal membrane and structures. (c) The deep muscles. (Reprinted from Scientific foundations of
obstetrics and gynaecology, ed by E Phillipp & M Setchell, chapter 8: The vulva, vaginal and
urethra and the musculature of the pelvic floor, by CP Wendell Smith and PM Wilson., pp 84–100,
published by Butterworth Heinemann, Copyright Elsevier 1970)
2 Anorectal Anatomy Related to Anal Fistula and Abscess 19
perineal body posteriorly and the corpora cavernosa anteriorly. Ischiocavernosus
attaches laterally to the ischial tuberosity and medially to the corpora cavernosa. The
transverse perineal muscles tether the perineal body to the ischial tuberosities
(Wendell Smith and Wilson 1970 ).
7 Extra-anal Spaces/Ischioanal Fossae
The perianal space surrounds the anus caudal to the lowermost extent of the external
anal sphincter. It is bounded superiorly and laterally by the longitudinal muscle as it
inserts into the perianal skin and inferiorly by the perianal skin (Fig. 4). Sepsis in this
space results in a perianal abscess or low fistula-in-ano and can spread laterally into
the ischioanal fossae (Milligan et al. 1937; Standring 2016a).
Lateral and posterior to the anal canal lie the ischioanal fossae. These triangularshaped spaces are bounded superiorly by the levator ani, laterally by the obturator
internus and ischial tuberosity, and inferiorly by the skin of the buttock and perineum. The anal canal lies medially. These two spaces communicate posteriorly
behind the anal canal and extend anteriorly in the space between levator ani and
superficial perineal muscles as far as the pubic bone. They are filled with loose
adipose tissue and are therefore routes for sepsis to spread, either anteriorly within
the perineum or across the midline via the posterior communication of the spaces in a
horseshoe configuration (Standring 2016b).
Superior to the pelvic floor and inferior to the pelvic peritoneum, there is a
potential space posterior and lateral to the rectum, the pararectal space. This is
another route by which sepsis can spread in a horseshoe manner from one side to
the other.
8 Anal Glands
A variable number of anal glands sit in both the submucosal and intersphincteric
spaces, with those situated in the intersphincteric space constituting up to two-thirds
of their total. Intersphincteric anal gland ducts traverse the internal sphincter to open
into the anal canal lumen, via crypts situated above the anal valves at the dentate line
(Fig. 5). They are branched glands consisting of stratified columnar epithelium and
containing mucin-secreting goblet cells. The glands are associated with the presence
of lymphocytes (Hill et al. 1943; Seow-Choen and Ho 1994). Ascending bacterial
infection of these glands is thought to be the origin of idiopathic or cryptoglandular
perianal sepsis and subsequent fistulating disease.
The glands are not equally distributed around the anal canal – the majority are
located posteriorly. Obstruction and resultant infection of these posterior glands
result in posterior ly situated abscesses, which can erode into the postanal space
and spread into the communicating ischioanal fossae, explaining the observed
Goodsall’s rule of posteriorly located external openings tracking to a posterior
midline opening.
20 K. R. Cattle and T. M. Hammond
Fig. 4 The attachments of the longitudinal muscle delineate the boundaries of the perianal space.
(Reprinted from The Lancet, Vol. 230, Milligan, E. T. C., Morgan, C. N., Jones, L. E., & Officer,
R. (1937). Surgical anatomy of the anal canal, and the operative treatment of haemorrhoids, Pages
1119–1124, Copyright (1937), with permission from Elsevier)
9 Relationship of Anatomy to Pathogenesis, Classification,
and Management
In 1976, Sir Alan Parks classified anal fistulae into four groups (see Fig. 6). The
classification is based on the anatomical spread of sepsis from the infected anal gland
in the intersphincteric space following the path of least resistance along the fibers of
the conjoi nt longitudinal muscle as they branch through the anal sphincter complex.
The aim of the classification system is to help the surgeon appreciate the topographical relationship of the fistula to the individual patient’s anal sphincter complex and