of a method of demonstrating the visceral pelvic fascia in bodies

THE ANATOMY OF THE VISCERAL PELVIC FASCIA.By R. ATKINSON STONEY, M.B., Visiting Surgeon to theRoyal City of Dublin Hospital; Chief Demonstrator ofAnatomy and Joint Lecturer in Applied Anatomy, TrinityCollege, Dublin. (PLATES XLIV. AND XLV.)

BY the introduction of formalin as a hardening reagent in thestudy of anatomy, not only have many new facts been discovered,but others which were already known have become more easyto demonstrate. I shall commence by giving a short accountof a method of demonstrating the visceral pelvic fascia in bodieswhich have been hardened in formalin. After hardening byinjection or immersion, the pelvis is cut mesially, and it isthen found possible to remove the viscera out of the capsulesformed for them by the pelvic fascia, and so obtain an un-interrupted view of the formation and connections of theseensheathments.

The method adopted is as follows:-In the case of theprostate, the handle of the knife is introduced between theposterior cut edge of the prostate and its capsule; it is found thatit can be pushed up to the junction of the bladder and prostateand downwards to the point where the urethra pierces the deeplayer of the triangular ligament, and that it can be pushedcompletely round the gland, so as to emerge between theanterior surface of the prostate and its capsule. On cuttingacross the apex of the prostate, where it is pierced by theurethra, the prostate can be lifted out of its capsule; the onlyplace where there is any difficulty in freeing the gland from itscapsule is close to the middle line in front, and at the apexwhere it is pierced by the urethra.

In the case of the bladder also the capsule may be dissectedoff; but as it is very much thinner than that which surroundsthe prostate, and more adherent, the cutting edge of the knifehas to be freely used. Behind the bladder is a thick-walledcapsule, from which the seminal vesicle and vas deferens may

THE ANATOMY OF THE VISCERAL PELVIC FASCIA.

be removed; this, as we shall see, is formed by a splitting of thefascia forming the posterior portion of the capsule of thebladder.

Dissections made in this way illustrate the visceral pelvicfascia in a very striking manner, and bring out some pointswhich I believe to be new.

Speaking in general terms, one might say that the viscerallayer of the pelvic fascia, instead of dividing into three layers,as usually described, gives off three sheaths-two in a downwarddirection to surround the prostate and rectum, and one in anupward direction to surround the bladder; and that each ofthese sheaths is separate and complete in itself, and in no placedoes one layer of fascia take part in the formation of more thanone sheath. (Plate XLIV.)

The dissection represented in Plate XLIV. was made lastautumn in a series of eight male pelves hardened in formalin.In the preparation which is figured the prostate was slightlyenlarged, and the separation of the prostate from its capsulewas, if anything, slightly easier than in the case of the others.The following is a description of the visceral pelvic fascia,

as demonstrated by these dissections.The visceral pelvic fascia is a layer of fascia which passes

in a somewhat obliquely transverse plane across the pelvis,separating the pelvic cavity above from the perineum below.It has a circular attachment to the parietal pelvic fascia; onlyover a small extent in front does this attachment fail, and herethe visceral layer gets a direct attachment to the bony wall ofthe pelvis above the parietal layer. In front the visceral layersprings from the back of the symphysis pubis, about three-quarters of an inch above its lower border; from this the line ofattachment gradually falls to the spine of the ischium, meetingthe upper border of the parietal layer after a course of abouthalf an inch on the back of the pubis. The attachments, there-fore, of the parietal and visceral layers cross each other on theback of the pubis like the limbs of the letter X, and a smalltriangular interval is left on the back of the bone between theattachments of these two layers of fascia, from which theanterior fibres of the levator ani muscle take origin directlyfrom the bone.

439

MR R. ATKINSON STONEY.

The line of attachment, as it stretches from the pubis to thespine of the ischium, passes obliquely across the obturatorforamen; here there is a thickening of the parietal layer, sothat, when viewed from the outside after the removal of thebone and obturator internus muscle, it has the appearance of awhite line. From the angle formed by the attachment of thevisceral to the parietal layer along this white line most of thefibres of the levator ani spring; but frequently it will be foundthat these fibres creep upwards for a variable distance, separat-ing the two layers from one another and making the attach-ment, in places, lie at a higher level.From the spine of the ischium the line of attachment of the

visceral to the parietal layer continues to fall until it reaches inthe middle line the junction of the fourth and fifth pieces ofthe sacrum.

Covering, therefore, the lowest piece of the sacrum and thecoccyx, and separating the posterior surface of the rectum fromthe bone, are two layers of fascia, namely the parietal and thevisceral layers of the pelvic fascia. Close to the mesial planethe parietal layer is difficult to demonstrate, as it is intimatelyblended with the periosteum; but as it is traced outwards oneither side over the coccygeus muscle it is more distinct, andon the lateral wall of the pelvis becomes continuous with thatportion of the parietal layer which is known as the obturatorfascia.

The visceral pelvic fascia, then, is to be considered as amembranous diaphragm, having a circular attachment to theparietal pelvic fascia, stretching across the pelvis between thepelvic cavity above and the perineum below, and covering theupper surface of the levatores ani muscles, which constitutethe pelvic diaphragm.

Passing from the pelvic cavity into the perineum are two setsof structures-the urogenital apparatus and the alimentarycanal-the former consisting of the bladder, urethra, prostate,and seminal vesicles, the latter consisting of the rectum and analcanal. These pierce the membranous diaphragm in order toreach their destination in the perineum. If it were not forthis fact, the visceral pelvic fascia would form an unbrokenseptum, stretching completely across the pelvis from the white

440


line on one side to the white line on the other side, and fromthe pubis in front to the sacrum behind, and would be assimple in construction as the layer of abdominal fascia whichcovers the under surface of the diaphragm. If the urogenitalorgans and the rectum are removed from a pelvis, we see, stretch-ing across and forming the floor of the pelvis, this continuous layerof fascia, interrupted in the middle line by two large openings,the anterior for the passage of the urogenital apparatus, andthe posterior for the passage of the alimentary canal. Betweenthe two the fascia can be traced continuously across the pelvisfrom one white line to the other. Plate XLV., which is drawnfrom a dissection, shows this appearance in one half of a pelvis.

The arrangement of the visceral fascia as it comes intorelation, first, with the urogenital apparatus, and secondly,with the alimentary canal, must now be considered.The visceral pelvic fascia passes inwards towards the centre

of the pelvis, from the back of the pubis in front, and from thewhite line on either side, till it meets the urogenital apparatus;this it does at the junction of the bladder and prostate; here itsplits into two layers, one passing up around the bladder, theother down around the prostate. As the layer passes up overthe bladder, it gradually thins on the front and sides, but maybe traced all over the bladder as a distinct and completecapsule; the portion covering the back of the bladder is greatlythickened, and is split into two layers on either side of themiddle line to enclose each seminal vesicle and vas deferens, butin the middle line these two layers are blended together again.The layer which passes down around the prostate forms a com-plete sheath which is somewhat funnel-shaped, having its broadend uppermost at the vesico-prostatic junction. It graduallytapers towards the apex of the prostate, where it meets the deeplayer of the triangular ligament, and gains a circular attachmentto it around the opening in the latter for the passage of theurethra. Here, therefore, around the urethral opening, thevisceral layer of the pelvic fascia represented by the capsule ofthe prostate is attached to the parietal layer represented bythe deep layer of the triangular ligament. These two layers,into which the visceral fascia splits, may be called the vesicalsheath or capsule and the prostatic sheath or capsule. Separat-

VOL. XXXVIII. (N.S. VOL. XVIII.)-JULY 1904. 29

441

MR R. ATKINSON STONEY.

ing these two capsules is a well-marked ridge, which fits intothe angle between the upper surface of the prostate and theunder surface of the bladder, as is well seen in Plate XLIV.

Besides this sheath of the visceral fascia which surrounds theprostate and is called the 'capsule of the prostate,' there is aspecial investment of fibrous tissue for the gland, which isclosely adherent to the gland and cannot be separated from itwithout lacerating the gland tissue. This is analogous to thefibrous capsules of the liver and spleen, and may be called thefibrous investment of the prostate.' This, of course, is notderived from the pelvic fascia. It is between these twosheaths that the prostatic plexus of veins is situated. Theseveins are chiefly massed in the middle line in front, and on eitherside in the angle of junction between the prostate and bladder;it is indeed this lateral mass of veins which is the chief factorin the formation of the ridge seen in Plate XLIV. separating thecavities from which the bladder and prostate have been removed.The visceral pelvic fascia, as it passes back from the pubis tothe urogenital apparatus, is specially thickened into two bands,one on either side of the middle line; these thickenings arecalled the pubo-prostatic ligaments or anterior true ligamentsof the bladder. In the middle line between these two ligamentsthe fascia is much thinner, and dips down so as to form a smallpouch which will just admit the tip of the finger, but acrossthe bottom of which the fascia can be traced. As a rule, itwill be found that the point at which the visceral layer meetsthe urogenital apparatus in front sinks somewhat below thevesico-prostatic junction, and is situated a little above themiddle of the anterior surface of the prostate, so that thevesical layer has to pass up over the prostate for a shortdistance before it reaches the bladder. This attachment islowest in the middle line and rapidly rises on either side till itreaches the vesico-prostatic junction, close to the attachment ofthe pubo-prostatic ligaments; in this way a somewhat V-shapedportion of the anterior surface of the prostate is covered by

1These names, capsule of the prostate, and fibrous investment, ought probablyto be reversed, but the name capsule of the prostate has been used so long todesignate the sheath derived from the pelvic fascia, that it is probably too late totry and alter the names.

44'2


what is really the vesical layer of the visceral pelvic fascia.This is shown in Diagram 1.

There is a space formed behind the pubis, between it and thedeep layer of the triangular ligament in front, the visceralpelvic fascia above, and the anterior portion of the capsule ofthe prostate below (see Diagram 1). In the middle line thisspace is greatly reduced in size, owing to the pouching down ofthe visceral fascia between the two pubo-prostatic ligaments

ritoneum. --

sheath..~ -

ymphyuls. . ---t@ <\ 4iv A , P>P epv. f.

oecat. ligt. -*Rectal sheath.

capsule. - - t vesle- - - - 5~HRectal sheath.

Fascia of Colles. a ITriangular ligt.

Par. pelv. fascia.

DIAGRAM 1.

and the sinking down on the anterior surface of the prostate ofthe attachment of the visceral fascia, as described above; buton either side, under the pubo-prostatic ligaments, the spaceis larger and is very distinct. Lying in this space is somefat, the amount varying with the development of the adiposetissue in the body; but more important than this, on either sideof the middle line are the anterior fibres of the levator ani asthey spring from the posterior surface of the pubis. The-muscles of either side meet in the middle line by their anterior

443

4MR R. ATKINSON STONEY.

borders and have no fascia intervening between them, as thevisceral fascia passes continuously across the middle line ontheir upper surfaces from one pubo-prostatic ligament to theother. As the anterior borders of the two levatores ani passbackwards, they separate so as to embrace the apex of theprostate as it is being pierced by the urethra; behind this theymeet again and pass backwards in company to the rectum. Atone point, therefore, and at one point only, namely, the apex of

J

~BLADDIER

Par. pelv. fascia.Vesical sheath.

obtur. int..9S~-_ __ visc. pelv. fascia.

\S Lev. ani.

_________ -- ~~Capsule of prostate.PProstate.

of t t n tThyroid membrane.-- - - ~urethra.

Pubic arch.Par. pelv. fascia..Comp. ureth.Triangular ligt.

DIAGRAM 2.

the prostate, does the visceral layer (represented by the capsuleof the prostate) turn round the anterior border of the levatorani and join the parietal layer (represented by the deep layer ofthe triangular ligament). (See Diagram 2.)

Behind the urogenital apparatus the visceral layer of thepelvic fascia passes in from the posterior portion of the whiteline and the line of its attachment to the parietal layer, whichstretches from the termination of the white line at the spine ofthe ischium to the junction of the 4th and 5th pieces of the

444


sacrum. As it does so it meets the rectum at its junctionwith the anal canal. It is then carried down for a shortdistance on the walls of the anal canal in the form of atubular sheath; this may be called the rectal sheath of thevisceral pelvic fascia. This may be best understood byimagining that behind the urogenital apparatus the pelvis isseparated from the perineum by a complete septum of thevisceral pelvic fascia stretching from the vesico-prostaticjunction in front to the junction of the 4th and 5th piecesof the sacrum behind, and that through this the rectum ispushed, so that the anal canal projects below it, clothed by afunnel-shaped sheath it has drawn down with it in its passage,

The visceral fascia as it passes in from the side lies on the

Par. pelv. fascia.

Viso. pelv. fascia.8RCT_ MM--CUM

-- nal. lascia.Obt. lnt.

-- ectal sheath.

--- PudiC vessels, eta.Sphincter ext.

DIAGRAM 3.

upper surface of the levator ani muscle, and is led by it to thefront and lateral walls of the rectum (Diagram 3). Behind,it passes in from the parietal fascia as it covers the front ofthe sacrum at the junction of the 4th and 5th pieces, beingseparated from the inner surface of the parietal layer, as itcovers the coccygei muscles, by a small quantity of areolartissue. Owing to the close apposition of the rectum to thefront of the sacrum and coccyx, this portion of the visceralfascia may be said to meet the posterior wall of the rectum assoon as it springs from the parietal layer, but it is separatedfrom the muscular coat of the rectum by a quantity of looseperirectal tissue, in which lie numerous blood-vessels, and itdoes not come into close contact with the posterior rectal walluntil the junction of the latter with the anal canal-that is, the

445

4MR R. ATKINSON STONEY.'

same level at which the visceral fascia meets the alimentarycanal in front and at, either side. So although it might seem atfirst sight that the sheath of fascia surrounding the rectumwas more extensive on the posterior aspect of the gut than onthe front and sides, this appearance is merely due to theclose apposition of the rectum to the curve of the sacrum andcoccyx; and it may be shown that this is the true explanationby drawing the rectum forwards, for then it will be seen that'the upper part of the' fascia leaves' the rectal wall and forms ahorizontal shelf behind the rectum continuous with the fasciapassing in to the sides of the rectum on the upper surface of thelevatores ani; whereas the lower portion, i.e. that below therecto-anal junction, is more closely attached to the wall ofthe gut, and is therefore a part of the true rectal sheath.

There are two layers of fascia between the prostate and therectum, one covering the posterior surface of the prostate andbeing portion of the capsule of the prostate, the other coveringthe front of the gut and being portion of the sheath of therectum. These two layers meet above at the vesico-prostaticjunction, where they both spring from the portion of thevisceral fascia which may be said' to stretch across the pelvisbetween the urogenital apparatus and the rectum.

Passing forwards from the front of the sacrum on either sideof the rectum to the back of the bladder are the nerves andvessels going to supply the urogenital apparatus. The sacralplexus' lies. behind the parietal pelvic fascia, and therefore thenerves which cdme off fo-m it for the supply of the pelvicviscera have to 'pierce this fascia in order to reach theirdestination; as they do so, they carry with them sheaths fromthis fascia; the blood-vessels, of course, lie inside the parietalfascia. 'There is, therefore, on either side of the rectum adistinct 'septum composed of blood-vessels and nerves sur-rounded by areolar tissue and sheaths of fascia passing fromthe front of the sacrum on either side of the rectum to theback 'of the bladder ;' this septum lies above the visceral pelvicfascia, and is sometimes attached to its upper surface; but as arule, if the finger is placed on the upper surface. of the visceralfascia at the side of the bladder, it can be pushed backwards onthe upper surface o'f this fascia underneath the septum till it

446

Journ. ofA nat. and Phfsiology, July 1904.]

O

Parietal. branches ofinternal Iliac vessels.

Ureter.

Junction of 4th and5th pieces of thesacrum.

[PiLATrE XLIV.

Psoas muscle.

Deep epigastric artery.

External iliac artery.

- - Obturator artery andL nerve.

Vesical sheath.Symphysis.

Pubo-prostaticligament.

Space containinganterior fibresof levator ani.

Line of attachment of visceral toparietal layer.

V laye

REectum.

Sbeath for seminal vesicle.

Aliterior wall of rectal shleatilAtiwaa. 1lDeep layer of triangular ligament.Capsule of prostate.

Ridge separating capsules of bladder and prostate.

Urethral opening.

Mesial section of pelvis. Peritoneum and extra-peritoneal fatty tissue have beenremoved. The bladder, prostate, and seminal vesicle have been dissectedfront their fascial capsules, and time rectum has been removed just above itjillictioll with the anal canal.

MR R. A. 81ONEY on time Anatomy of the Visceral Pelvic Fascia.

Jourv. of AnaLt and Physiology, July 1904. ]

Psoas muscle.

Obturator cilnal.Symphysis.

White line.Cut edgae of visceral P. F.

Vesical sheath.Bladder.Urethra.

Seminal vesicle and vas.Sheath for do.Rectum.

Visceral layer of PP..-Parietal layer of P.F.

I ILine of attachment of visceral Meeting of visceral and parietal pelvic fascia at

to parietal layer. junction of 4th and 5th pieces of sacrum.

Deep layer of triangulilar ligament.

Section of pelvis. The upper part of sacrunm has been cut away very obliquelywith part of the innominate bone ; the peritoneum and extra-peritonealfatty tissue have been removed, also the greater part of the bladder, seminalvesicle, and rectum. The line of attachment of the visceral to the parietallayer has been somewhat accentuated in the drawing.

Mat R. A. S-roNEY on the Anatomy of the Visceral Pelvic Fascia

Sacro-iliac joint.-

[PLAT1 XLV.

THE ANATOMY OF THE V~ISCERAL PELVIC FASCIA. 447

reaches the middle line behind, showing that this septum haseither no attachment to the upper surface of the visceral fascia,or only a weak one which can be easily broken down.

It is seen from the foregoing account that the arrangementof the visceral pelvic fascia in front, as it comes into relationwith the urogenital apparatus, is very much more complicatedthan it is behind, where it is in relation with the rectum. Thisis due to two causes: first, the urogenital apparatus passes notonly through the septum formed by the visceral fascia, but alsothrough the parietal layer, where it forms the deep layer of thetriangular ligament, whereas the rectum has only to passthrough the septum formed by the visceral layer of fascia.Secondly, in addition to the sheath given by the visceral layerin- a downward direction to surround the prostate, which formsthe capsule of the prostate and corresponds exactly to thesheath of the rectum, there is another sheath given off in anupward direction to surround the bladder and seminal vesicles,forming the vesical sheath or capsule.

Documents

of a method of demonstrating the visceral pelvic fascia in bodies