84 Proc. roy. Soc. Med. Volume 63 (1970)

HughesE S R, Cuthbertson A M & Carden A B G hibitory response to rectal distention, the inhibi- (1962) Med. J. Aust. ii, 907 Kennedy J, McOmish D, Bennett R C, Hughes E S R tion occurring reciprocally with the stimulated & Cuthbertson A M (1968) Proceedings ofIII Asian-Pacific rectal wave in the normal subject. Congress ofGastroenterology. 1, 177 Kister (1891) quoted by Albarran (1909) Niehans P (1888)Zbl. Chir. 15, 521 Method ofStudy Pousson A & Desnos E (1921) Encyclop6die Frangaise based on the d'Urologie. Paris; 4,1056 Anatomy: The anatomical study is Ryan P (1969) Proceedings ofRoyal Australasian College of examination of the pelves of 13 neonates and Surgeons Seminar on the Management of Road Traffic Casualties infants dying of conditions unrelated to the ano- (in press) Tuffier T (1894) Gaz. hebd. Mid. Chir. 41, 195 rectum. The pelves were isolated by subcutaneous Weyrauch H M (1959) Surgery ofthe Prostate. Philadelphia dissection to include the perineum in the speci- men. These specimens were either dissected or Postscript: On 10.2.70, in a male patient aged 62, submitted to serial section in the sagittal, trans- the author first carried out transpubic low verse or coronal plane, and stained with either anterior resection and anastomosis ofa carcinoma hmmatoxylin and eosin, or phosphotungstic acid of the rectum 5-6 cm from the anal verge (at its and eosin. lowest point) with a margin of 3 cm below the lesion-that is, an anastomosis was made 2-3 Physiology: A pressure profile was recorded from cm from the anal margin. the anal canal from a 2-chamber or 4-chamber probe (Fig 1), 0 4 or 0 5 cm in diameter, recording a squeeze pressure profile at 1 cm intervals through the anal canal. A rectal balloon set 5 or 8 cm from the anal verge recorded intrarectal pressure and when inflated acted as a distending stimulus to the rectum. In the recorded traces allowance was made for body temperature and Structure and Function of the rubber distortion. From the anatomical studies it is apparent that Internal Anal Sphincter there are two distinct parts of the internal anal by J 0 N Lawson" FRCS sphincter. These are seperated by the attachment (Hospitalfor Sick Children, Great Ormond Street, London WC1) The first anatomical description of the internal anal sphincter is attributed to Henle in 1866 (Uhlenhuth 1953). The inhibitory response in the sphincter to rectal distention was first reported by Garry in 1932. Since this time there have been a number of detailed accounts of the anatomy, physiology and embryology of the sphincter. For the purpose of this account the internal anal sphincter is defined as the lowermost part of the circular smooth muscle coat of the alimentary canal. This portion shows, anatomically, a characteristic oval bundle arrangement of its fibres and lines the surgical anal canal or pars analis recti, extending down to a point just above the anus. This portion shows a characteristic in- 'Present address: St Thomas's Hospital, and Westminster Fig IA Four-chamber anal probe. (Reproducedfrom Children's Hospital, London Lawson & Nixon 1967 by kind permission) 0.2 cm 0.5 cm 0.8 cm 2.5 cm

l ~ ~ (~ l 1 lJ:I I I 3 cm 1cm 4 cm 4 cm 1.2 cm

Fig I B Exploded diagram of-anal probe. (Reproducedfrom Lawson & Nixon 1967 by kindpermission) Supplement

Rectal longitudinal muscle

Fig 2 Diagrammatic representation of internal anal sphincter dnd its associatedstructures. SCZ, stratified cuboidal cell epithelium. ACS, anal canalskin

Fig 3 Coronal section neonatalpelvis showing Fig 4 Transverse sectionoffemaleneonatal submucosal muscle arisingfrom medial edges of pelvis to show contributionfrom bundles ofupperpart ofthe internal anal sphincter. longitudinal smooth muscle coats to tipper 1, submucosal muscle. 2, upperpart ofinternal internal anal sphincter. I ,fibresfrom sphincter. 3, lowerpart ofinternalsphincter. 4, longitudinal coat spiralling into internal pubosphincteric or 'rectalis' sling. 5, deep anal sphincter. 2, longitudinal coat. 3, upper sphincter. 6, superficial analsphincter. 7, puboanalis. partofinternal sphincter. 4, lumenofupper 8, ischial tuberosities. 9, ampulla ofrectum. anal canal orpars analis recti. 5, vagina. PTAH. x 7-5 PTAH. x 7 5 86 Proc. roy. Soc. Med. Volume 63 (1970)

...... Fig 5 Sagittal section to show origin ofinternal sphincterfrom perineal body (inferior rectourethral Re Rect l so muscle). 1, pubis. 2, coccyx. 3, prostate. 4, deep anal 40- sphincter. 5, superficialanalsphincter. 6,pubosphincteric 20 - or 'rectalis' sling. 7, puboanalis sling. 8, anterior sacrococcygeal ligament. 9, inferior rectourethral 2nd cm 40 muscle. 10, rectourethralis (orperineus). H & E. x 5 2 20 2B0

l tcm 40 X _ 20

E G .I ..

Pneumo. Time/Sec Fig 7 Infant resting trace showing squeeze pressure trace takenfrom lower anal canal (Ist cm) and upper anal canal (2ndcm) showing differing rates of rhythmical activityv

' ,\c/jiJ la\v {. ;oJ\i,- sts. tX_..\jAE 0k/t5#Z*uarL,i'e\<1~~~~~~~~~~~~~~~~~~~_.,e..> Vrsy,t'\A-Voj!..... ownaud

-I 0 - 10908 °

.~~~~~~~~~~~~~~~0 _o c oz r I

_08

Fig 6 Transverse section offemale neonatalpelvis Fig 8 Childhood resting trace showingprominent (detail) to show region ofperineal body and origin of rhythmical activity in Hirschsprung's disease at lowerpart ofinternal analsphincter. Also differing rates in the lower anal canal cm) and 'rectourethralis' or rectoperineus. 1, insertion oflower (1st portion ofinternal sphincter intoperineal body. 2, upper anal canal (2nd cm) 'rectourethralis' or rectoperineus. 3, lumen ofanal canal at level ofanal crypts. 4, transverseperineus. 5, conjoined longitudinal muscle. 6, submucosal muscle in anal column. PTAH. x 7-5 Supplement 87

100 NEUROGENIC RECTUM 00 60 401- Effect of Penneal Stimulation

{R ectal -60 VBalb=>/ 40_ >) 8oo 20 - 0 60 X 4 [ 40

3 g so _28 40 - 80

PAS PAS

iiiI iI(Ii I;'J IdII~o Fig 9 Neurogenic rectum (lower motor U 1; neurone lesions) showing presence of III!!I III 11 L1 ~~~~~~~~~~~~~~~~~~~~~I .1 rhythmical activity in spite ofabsence of rm , I!m mIt r m m mmdr 1, m 1 mn!jl,i.-I contraction ofvoluntary sphincter in response toperianal stimulation of the pelvic floor, puboanalis and anterior sacro- ment may be explained by the finding of Johnson coccygeal ligament to the anal canal (Fig 2). (1914) that the longitudinal muscle fibres of the Above this insertion the internal sphincter is embryonic bulboanalis grow down ahead of the characterized by oval bundles whose axes lie circular, in the 22-8 cm embryo. The subsequent obliquely downwards and inwards. These are clockwise rotation of the bulboanalis on the readily distinguishable from the quadrilateral bulboterminalis at the 29-30 mm stage may bundle of cilcular muscle in the rectum above. explain the large contribution from the longi- Furthermore, the contribution of fibres from the tudinal coat and the subsequent spiral arrange- longitudinal to the circular muscle in the rectum ment in the upper internal sphincter. is not prominent. Below, in the upper internal The similarity in level at which this occurs in sphincter it becomes very marked. the embryo and the subsequent level of this part The submucosal muscle (described by of the sphincter in the mature anal canal is shown Kohlrausch in 1854) arises from the medial edges by two structures: (1) In the embryo the bulbo- of the bundles of the upper internal sphincter. terminalis is lined with stratified cuboidal cell Consisting of fibromuscular bundles, it passes epithelium. (2) The muscularis mucosa dis- down through the submucosal folds of the upper appears at the junction of the bulboanalis and surgical anal canal intothe anal columns and folds bulboterminalis. In the mature canal the upper to insert into the skin at the anal verge (Fig 3). sphincter is related to the stratified cuboidal cell It appears that the fibres of this part of the zone and the muscularis disappears abruptly at sphincter arise in the longitudinal coat and spiral the dentate line. into the sphincter, to complete their course as In our studies of anorectal agenesis, the upper the submucosal muscle (Fig 4). This arrange- portion only with a lining of stratified cuboidal too PERINEAL ECTOPIC ANUS

40.40 Resting Recta 20 _ 100 00 so 100 640

40 100 E 3 E 20 - °- -

E X 80 40-20_

-EMG... "a .~ I. .. 1. 1-1- - LL'i- H 1. 1. , ., - I-II. .], I. --i , -1- -.L 0. -1 " "I ., Fig 10 Resting tracefrom case ofperineal -,- , MT.. - v ectopic anus showing rhythmical activity in lilrlllyiiiiiiii ! upper and lower anal canal at same rate 88 Proc. roy. Soc. Med. Volume 63 (1970)

100 VULVAL ECTOPIC ANUS 00 folds; they contribute, with the pelvic floor so attachment and anal glands, to the tethering of 40 Resting 20 80 the mucosa ectal between these folds. 601_ In Ball 40 front, broad bands of smooth muscle (the 20 inferior rectourethral muscle of Roux), arising on 100r either side from the perineal body, enter the 80 0 4 600 sphincter (Figs 2, 5, 6). These are well seen in true sagittal, transverse and coronal section. In the 2 E _~,- dissection the sphincter can also be seen to arise E- _ 1000 40 2080 -_8020 from a short raphe above the perineal body. 600- The 40 fibres appear to loop into the sphincter 40 - and spiral into bundles below the level of the perineal body where the direct contributions from this structure disappear. In our study of cases of anorectal agenesis this part of the sphincter appears to arise from a more primitive cloacal sphincter, as in some transverse sections con- tinuity between the lower internal anal sphincter can be traced into the internal urinary and vaginal ._vttv trrmirn~ r- rTl.,rTI-ttrr1tTVTvv,T1TT,f-,0,00177vT tt,rnn,vT r7tVVV- sphincteis. Fig 11 Resting tracefrom vulval ectopic anus treated In our pressure studies we have demonstrated by cut back. Rhythmical activity is seen only in the 3rd intermittent rhythmical activity in the anal canal cm ofthe anal canal of most normal children at a rate of 10-13 per minute (Fig 7). In Hirschsprung's di,ease this cell epithelium is seen in prostatic, vaginal, activity is particularly prominent and persistent. perineal and vulval openings. Where rhythmical activity is seen in thc trace The puboanalis, at its insertion into the anal from the lower third of the anal canal it is present canal, consists of two layers of musculotendinous at a more rapid rate than that from the upper slips. Those forming the upper layer pass two-thirds. The ratio is usually in the region of obliquely downwards and medially between the 3:2. It is well demonstrated in Fig 8, from a case bundles of longitudinal muscle to reach the anal of Hirschsprung's disease. The activity through- skin at its junction with the stratified cuboidal out the sphincter continues at a different rate cell zone. The insertion of the anterior sacro- from the respiratory rate and continues when the coccygeal ligament behind completes the separa- breath is held. It also continues in lower motor tion of the two parts of the internal sphincter. lesions involving the pelvic floor and voluntary Below the pelvic floor attachment, in sagittal sphincters (Fig 9). section, the circular muscle bundles of the in- This rhythmical activity is demonstrable, ternal sphincter assume a different shape (Fig 2). though only at the one rate, in cases of perineal Those lying posteriorly are petal-shaped but those ectopic and vestibular ectopic anus (Figs 10 and in front remain oval. Their axes come to lie trans- 11). In 7 out of 17 cases of constipation persisting versely and then upwards and medially, con- from birth, the amplitude of waves recorded from verging on the upper border of anal skin where the upper part of the internal sphincter was fibromuscular extensions insert between the anal markedly increased (Fig 12).

Time/Be ""mmr"rtrnclnltr . . . .ttttttwr7tr rt"rtrffr"?Wmrtntmrtno Fig 12 Resting tracefrom child with constipationfrom birth. Veryprominent rhythmicalactivity is seen in the upper anal canal (2ndcm) Supplement 89

Summary needle is then inserted into the submucosa of the The internal anal sphincter consists anatomically normal rectal wall adjacent to the tumour and of two portions; an upper part extends down isotonic saline with adrenaline 1 part in 300,000 through the upper two-thirds of the 'surgical' is injected. Sufficient saline is used to lift up the anal canal while the lower portion lines the lower whole tumour off the rectal wall muscle. An one-third. The structure of the two portions is incision in the normal mucosa surrounding the described and the developmental origin of these tumour is made about 1 cm from the edge. Dis- parts is suggested. section is carried out in the submucous plane Intermittent rhythmical contraction unrelated close to the circular muscle of the rectum. The to voluntary contraction is seen in the anal canal whole tumour is removed in one piece if not too and corresponds with that part showing the recto- large, but it may be necessary to remove it in anal inhibitory response. This activity is promi- segments. In this case the retractors are removed nent in Hirschsprung's disease where inhibition and reinserted to expose a fresh portion of the fails to occur. The differing rates of this activity tumour for excision separately. No suturing of are observed in the two parts of the sphincter. the rectal mucosa is required in most cases as Similar activity to that in the upper portion is even laige bare areas of rectal wall will heal with noted in ectopic anus confirming the anatomical relatively little narrowing of the rectum. findings of an internal sphincter in the so-called A more extensive procedure is required if the fistulh of imperforate anus. villous papilloma occupies the entire rectal wall. However, it must be stressed that it is never REFERENCES necessary to excise the rectum and perform a Garry R C (1932) J. Physiol. (Lond.) 18, 136 Johnson F P (1914) Amer. J. Anat. 16, 1 permanent colostomy for a benign tumour. The Kohlrausch 0 (1854) Zur Anatomie und Physiologie der Becken- procedure is similar to that already descrlbed organe. Leipzig Lawson J 0 N & Nixon H H except that the whole of the lower 8 cm of the (1967) J. pediat. Surg. 2, 544 rectum is completely denuded of the abnormal Uhlenihuth E (1953) Problems in the Anatomy ofthe Pelvis. mucosa above the pectinate line. If nothing Philadelphia further were done healing would be complicated by a stricture so that the rectal wall must be relined with epithelium. Rectal continence does not depend on the mucosa; the essential factor is the muscle wall (Parks et al. 1962). Provided, therefore, the muscle wall can be relined with A Technique for the Removal of mucosa a normally functioning anorectal mechan- Villous Tumours in the Rectum1 ism will result. This has been achieved by pulling Large a segment of sigmoid colon down through the by A G Parks Mch FRCS denuded rectum to the pectinate line. When (The London Hospital and the whole rectum is involved with villous change St Mark's Hospital, London) the mucosa has to be removed in segments. Once this has been done a lower abdominal incision is Management of an extensive villous papilloma made and the upper rectum mobilized. The of the rectum is often difficult. The tumour fre- rectum is transected at the upper level of the quently forms a carpet occupying a considerable mucosal excision and if any tumour remains in portion of the rectal ampulla; it may even en- the bowel above this point a partial sigmoid circle it completely. In rare cases the whole colectomy is performed. The upper sigmoid colon rectum and rectosigmoid are involved in the neo- is then drawn down through the denuded rectum plastic process. and sutured to the squamous epithelium of the A tumour which has not completely encircled mid-anal canal at the pectinate line (Fig 2). A the rectum can be removed relatively simply. The few sutures are placed between the muscularis principle of the method depends on the fact that and the cut end of the upper rectum and the wall the submucosa of the rectum is an easily dis- of the colon. The reconstituted rectum now has tensible space. Fluid injected into it spreads two muscle coats and an epithelial lining derived rapidly in all directions and distends the space from the colon. A temporary transverse colos- to a thickness of 1-2 cm. The tumour is then tomy is then performed and closed three weeks removed quite easily by dissecting underneath it later. In the 2 cases in which this more extensive in the distended submucous plane (Fig 1). An procedure has been performed the functional anal retractor is inserted into the rectum and results have been excellent and the patient has opened to expose part or all of the tumour. A been normally continent. Before performing this "This paper is based on a report previously published in the operation one must be sure that there are no areas Proceedings (Parks 1968) of malignancy in the villous tumour. It is essential

4