broad, relaxed band of muscle situated beneath the external skin and
surrounding the infra-anal depression. In action the ectal sphincter is
contracted and is retracted from beneath the external skin to a point
beneath the mixed mucocutaneous integument. In such a state of ectal
sphincter contraction the fixed portion of the rectum is lengthened,
or in other words, the pelvic floor is deepened one-half inch (1.27
cm.), approximately. The finger progressing, it engages the tonicly
contracted ental sphincter muscle which the delicate touch discovers
as vibratory in its grasp of the finger, presenting to the touch the
sense of a sharp rigid ring, and again as a flat band snugly applied
about the finger. A few lines above the ental sphincter the finger
discovers the upper limits of the fixed or anal portion of the rectum
surrounded by the somewhat V- or U-shaped borders of the levator ani
muscle; the anterior quadrant is not encircled by the levator ani.
The fixed portion of the rectum presents, then, to the touch, three
landmarks: the usually relaxed ectal sphincter, the usually contracted
ental sphincter, and the levator ani muscles. The normal levator ani
muscle can not by the contraction of its fibers close the upper end of
the fixed rectum. It is possible, however, for the patient to contract
his levator upon the finger of the examiner to quite an appreciable
degree, a fact which led Mr. Harrison Cripps to state that the levator
ani can close the upper end of the fixed rectum. If a tubular speculum
of seven-eighths of an inch (2.22 cm.) diameter be introduced through
the fixed rectum and then withdrawn through the levator ani to a point
above the ental sphincter and the patient be directed to contract the
muscles of the pelvic floor, it may be observed that the axis of the
fixed rectum is directed more forward at its upper end, and that the
depression between the levatores ani is partially encroached upon by
the levator fibers but is in no sense effaced; hence, we must recognize
that the lower fixed portion of the rectum presents a canal of an
hour-glass form, expanded above as a concavity between the borders of
the levatores ani, narrowed at its middle part by the contracted ental
sphincter, and expanded below where it is surrounded by the relaxed
ectal sphincter muscle.
In the same subject the length of the fixed anal rectum is variable
with a state of activity or passivity, and in a state of activity there
are variations in its length of at least one inch (2.54 cm.) between a
contracted, uplifted pelvic floor and that of a depressed floor with
anal eversion; both of which conditions may rapidly follow one upon
the other while the examiner’s finger is engaged in diagnosis. Again,
variations in depth of the fixed anal rectum are quite noticeably
regulated by the size of the finger introduced. The thumb may find
a fixed anal rectum of two inches (5.08 cm.) in depth, while the
little finger discovers it but a little more than an inch (2.54 cm.).
Because of the bony confines to the tissues of the ischiorectal space,
displacement of its structures to open the anus must occur in the
vertical direction, the larger the finger the greater the displacement
upward.
Passing the finger beyond the borders of the levator ani, the distal
phalanx enters the movable or abdominal rectum, where it may be hooked
over the pelvic floor. In some instances, if the finger be directed
backward and crowded with a boring maneuver through the loose folds of
the movable rectum, and provided the folded knuckles displace upward
the pelvic floor, the finger may be made to engage the lowermost of the
rectal valves, which will contract about the finger with a rhythmic
action and mislead the uninformed, inexperienced and undiscriminating
explorer to think that he is but now encountering the ental sphincter
muscle, or, perhaps, that he has discovered a stricture--the phantom
stricture? In the passive rectum, this valve is usually about three
inches (7.62 cm.) above the lower border of the ental sphincter muscle.
The great range of mobility of the pelvic diaphragm permits a finger of
two inches (5.08 cm.) length to be hooked over a valve which under some
circumstances may be an inch and a half (3.81 cm.) beyond its reach.
The pelvic floor in the infant is often less than one-half inch (1.27
cm.) in depth. The depth of the pelvic floor in the adult, from the
lower border of the relaxed ectal sphincter ani muscle to the levator
ani muscle, is extremely variable. In the aged male, because of senile
enlargement of the prostate, the fixed rectum may seem to be three
inches (7.62 cm.) in depth. In the aged female, because of senile
atrophy of the generative organs and contiguous structures, the pelvic
floor may be much less than an inch (2.54 cm.) in depth. In the adipose
and in emaciated subjects because of the character of the tissues
occupying the ischiorectal space, there are the greatest variations in
the depth of the pelvic floor. Hence, it is obvious that the palpable
muscular landmarks of the fixed rectum are situated at variable
positions in the different sexes, and that the length of the fixed
rectum is changed in the same person at different periods of life and
in differing conditions of flesh.
The visible topographic features of the fixed rectum are several,
and under the influence of disease may become somewhat changed in
appearance and situation. In the male they are readily discoverable by
putting the subject in the dorsal posture, separating the nates with
the hands and placing the thumbs on bits of dry cotton to prevent their
slipping just exterior to the anus. Simultaneously to the patient’s
bearing-down impulse the thumbs may be used to evert the anal mucous
membrane. The anterior and posterior borders of the anus may in a
measure be everted by a somewhat similar manipulation. In the female
the visible landmarks of this region may be inspected by entering the
finger into the vagina and placing the thumb over the perineum; the
former is to push the rectum down while the thumb draws the external
skin forward over the perineum. The posterior segment may be exposed
by pushing the post anal skin toward the coccyx; the lateral segments
may be exposed with the finger and thumb of the left hand while the
right hand keeps up the initial pressure. Marked pigmentation of
the anal skin is observable in a circumscribed area about the anus;
beneath this area of darkened skin, intimately attached to the skin,
lies the surgically unappreciated corrugator cutis ani. Within the
borders of the everted anus the complexion fades to a light gray,
within which zone is sometimes noticeable the distinctly lighter zone
known as Hilton’s white line. Above, is noticeable an undulating
zone of deeply red mucous membrane the lower border of which has been
given the name of _linea dentata_ (Stroud). Between the linea dentata
and the white line is a zone occupied by several pyramidal elevations
about half an inch (1.27 cm.) in length, to which has been given the
names: columns of Morganni and pecten of Stroud. Their bases are of a
somewhat purple reddish color. Toward their apices they may pale and
terminate in projecting white eminences. The bases of these pyramids,
which, I believe, may without impropriety be called anal pilasters,
are extremely vascular and their structure partakes somewhat of the
character of erectile tissue. The apex contains a nerve end-bulb.
Under the influence of disease the color of these bodies is changed.
Their antemortem and postmortem appearance is quite different. There
are usually present in each anus from four to eight of these bodies.
Between these projections and at their lower borders, sometimes, there
is discoverable a thin fold of membrane. The saccule which it, together
with the anal wall and pilasters on either side, forms, has been known
as the saccule Horneri, pocket of Physic, and anal pocket, sometimes
inaptly called rectal pocket. Its cavity is about the size of a split
pea. The three typic visible topographic features of the fixed rectum,
then, are the white line of Hilton, the pecten of Stroud, or anal
pilasters, and the linea dentata.
The mucocutaneous membrane of which these visible landmarks are a part,
rests upon a quantity of loose connective tissue, which permits of a
great range of mobility of these features independent of movement of
the structures constituting the palpable landmarks of the fixed or anal
rectum.
[Illustration: FIG. 21.--From a photograph of an external view of the
paraffin cast-filled rectum. The rough surface shows the place of
attachment of the peritoneum.]
[Illustration: FIG. 22.--Interior view of the left half of the rectum
of an adult. Filled with melted paraffin, the subject being in the
proctocolonoscopic posture. The rectum is distended only to the degree
of normal atmospheric inflation. When the wax was hardened the rectum
was removed, varnished, dried and cut open longitudinally. The picture
is a reproduction of a photograph of the interior of the left half
of the rectum. The anus is at the picture’s left. The valves are
respectively two and one-half and seven inches (6.35 and 17.78 cm.)
from the anus.]
[Illustration: FIG. 23.--Knee-chest posture. Left lateral half-interior
view. Upper rectum and sigmoid out of focus.]
[Illustration: FIG. 24.--Posterior view of a specimen carefully
dissected to show the muscular supply to the valve-bases.]
[Illustration: FIG. 25.--Posterior half occupied by its cast.]
[Illustration: FIG. 26.--Anterior half of specimen shown in Fig. 25.]
[Illustration: FIG. 27.--Posterior view of a cast-filled rectum.]
[Illustration: FIG. 28.--Paraffin cast from a rectum.]
THE RECTAL VALVE.
That the rectal valve constitutes the most hypsometric of the
topographic features of the movable abdominal rectum, is conclusively
proven by the photographic pictures. The specimens from which the
photographs were taken were prepared by a method consisting in fixing
the cadaver in the knee-chest posture and pouring melted paraffin into
the atmospherically inflated rectum; when the wax had sufficiently
hardened the gut was carefully removed, for a few weeks immersed
in alcohol and subsequently dried, varnished, and finally dried
and cut into longitudinal, shell-like halves. A comparative study
of the photographs of the rectal interiors discovers the fact that
_the prominence of the rectal valve is increased with the degree of
distention of the rectum_.
The accompanying drawing was made from a microscopic section taken
from the middle of the lower valve of an adult specimen. In the
illustration, Fig. 33, it is shown magnified 5 diameters. Beneath the
mucosa is noticeable the heavy layer of fibrous tissue which gradually
diminishes till it is lost at the valve base. Bundles of circular
muscular fibers are seen in the middle of the valve. At its base are
seen arteries and veins for its special nutrition. This structural
arrangement makes this organ the typic anatomic valve. The evidence of
the fibrous tissue in the valve is an original contribution to our
knowledge of this subject.
The attached border of each valve spans a little more than half the
circumference of the rectum, and its free border projects half across
the diameter of the inflated rectum. Each valvular partition projects
at nearly a right angle to the wall of the compartment below it and
terminates in a sharply defined free border. The free margin of
the structure is slightly concave in form and is directed a little
obliquely. In life it is noticeable that the free border of the valve
is less elastic than the main wall of the valve. The latter will
yield to a modicum of traction without disturbing its free border,
while traction applied at the margin may at once disturb the entire
circumference of the gut at that point. The rectal wall opposite
the valve is usually concave. The aperture thus formed between two
rectal compartments is irregularly elliptic; it may be called the
valve-strait. Usually the greatest diameter of a rectal compartment is
directed laterally or else obliquely; it is almost never parallel to
the direction of the sacrum. Thus, what has been heretofore considered
a cavernous ampulla is seen to be divided into several chambers.
There are as many chambers in the rectum as there are rectal valves.
The number of rectal valves is variable. Some subjects have but two,
others have four, but 90% of persons possess three. The uppermost valve
is invariably situated at the juncture of the rectum and the sigmoid
flexure, which valve is invariably situated on the left, the next lower
is on the right wall, and the lowermost is on the left. The positions
of the lower two valves are sometimes anterior and posterior.
The specimen shown in Fig. 30 exhibits the rectum naturally distended
with feces. It was found in a deceased member of the demimonde who
had been habituated to opium indulgence. She was forty years of age
and of robust stature. On opening the abdomen the colon was discovered
loaded with a collection of scybalous feces, and the upper chamber of
the rectum was partially occupied with a similar deposit. The abdomen
was then opened through the pubes and perineum down to the coccyx.
The genitourinary organs and contiguous structures were removed, the
symphisis forcibly separated and the exposed sigmoid flexure and rectum
were photographed as shown in Fig. 29. The sigmoid and rectum were
carefully removed and immersed in alcohol. After a fortnight the gut
was divided into anterior and posterior halves, as shown in Fig. 30.
[Illustration: FIG. 29.--Photograph of a female cadaver showing, after
laparo-symphysiotomy and removal of bladder, uterus and adnexa, the
upper rectum and sigmoid packed with scybalums.]
[Illustration: FIG. 30.--The rectum, the same as is shown in Fig. 29,
divided into anterior and posterior halves.]
It must be readily seen that the new methods of rectal inflation
for rectal inspection and the cast method of dissection, which have
determined our newer ideas of the topography of this part, justify
that the lowermost chamber be considered the first rectal chamber;
the cavernous area beyond the first valve and below the second
should be called the second chamber; and the upper chamber the third
or perhaps fourth, according to the number of valves. The ancient
arbitrary division of the rectum by the anatomists into upper first,
middle second and lower third parts should be abandoned because such
a method is inaccurate and has no surgical significance. As the
arrangement of the fibers of the muscular coats of the abdominal rectum
and the attachments of the abdominal rectum provide for extension
and contraction of the gut on its axis, as well as expansion of the
diameter of the organ, it is obvious that there must be in the same
individual a great variation in the distance of any given valve from
the levator ani with the variable normal states of the organ. The
normal range of movement upward and downward of a given valve is from
two to three inches (5.08 to 7.62 cm.).
A discriminating study of the diseases of the rectum requires an
arbitrary division of the organ into several quadrants.
Regard for the conveniences of scientific description and
considerations of technic and of anatomy justify that the fixed anal
rectum be called _the anus_, and that the movable abdominal rectum be
called _the rectum_. The former is bounded above by the levator ani and
below by the ectal sphincter muscle.
From this survey of the topography of the anus and rectum and
consideration of the arrangement of the contiguous structures the
following salient aphorisms may be deduced:
1. In treating lesions on a level with the sphincter muscles the
operator should beware of dividing these structures through the
anterior quadrant. In the male the ectal sphincter terminates in the
tendinous raphe in common with the transversus perinei. Contraction
of the transversus perinei will separate the cut fibers of the ectal
sphincter and defeat the desired subsequent union of this muscle.
If an incision be carried forward or forward and laterally into the
transversus perinei the perineal fascia which doubles over this muscle
will be opened and the perineum and peri-urethral structures will be
made accessible to infection from the anus and ischiorectal regions. In
the female, to carry an incision forward through the anterior quadrant
would be unsurgical because the peculiar arrangement of the fibers of
the ectal sphincter ani and sphincter vaginae and their relation with
the transversus perinei would perhaps conspire to produce vulvoanal or
rectovaginal fistulas.
2. A stricture located at the upper end of the fixed rectum and
situated in the anal fascia, in the pelvic fascia, or in the fibers of
the levator ani muscle, should not be cut in the anterior quadrant nor
in the posterior quadrant, but in one or the other, or both, lateral
quadrants. An incision through the anterior quadrant on the plane of
the levator ani muscle would divide none of its fibers because there
are none there and would endanger the urinary organs and vagina in
the male and female respectively. An incision made into the posterior
quadrant on this plane would fail to increase the diameter of the
rectum for the reason that contraction of the fibers of the levator
ani would hold in coaptation the lips of the wound in such a manner as
to early reestablish the stricture. A skilfully made incision in the
lateral quadrants in this region will not endanger the peritoneum. A
possible hemorrhage may be readily avoided by digitally ascertaining
the situation of the middle hemorrhoidal arteries. And because of the
direction of the fibers of the levator muscle a short lateral incision
will effectually increase the diameter of the part.
3. The rectal valve must be reckoned with in studying the strictures of
the movable abdominal rectum. Linear posterior proctotomy, because of
the relation of the peritoneum to the posterior wall of the lower part
of the movable rectum, is eminently safe, but will be efficacious only
in some special instances--those instances in which the rectal valve
involved is posteriorly situated. Semilunar (annular) strictures may
be situated at any point in the circumference of the movable rectum,
for they are built on the foundations supplied by the rectal valves,
and may be safely cut through to the depth of a quarter of an inch (.63
cm.), provided the surgeon be equipped with the proper instruments and
provided the rectum be maintained in a state of atmospheric inflation
at the time of the operation.
The studies of the topography of the human rectum made in this research
employed more than 50 autopsies, on subjects of all ages, and physical
examinations of many hundred living persons, and the facts which are
set forth above justify the inference, I believe, that none but the
topographic designation of the precise situation of the rectal lesion
is of reliable surgical significance.
Dissection of many rectums of rabbits, cats, dogs and monkeys proved
that these animals are not provided with rectal valves.
DEFECATION.
“Defecation is partly a voluntary and partly a reflex act. But in
the infant the voluntary control has not yet been developed; in the
adult it may be lost by disease; in an animal it may be abolished
by operation; in each case the action becomes wholly reflex. In the
normal course of events, the rectum which is empty and quiescent in the
intervals of defecation, is excited to contraction as soon as feces
begin to enter it through the sigmoid flexure, and the sensations
caused by their presence give rise to the desire to empty the bowels.
This desire may for a time be resisted by the will, or it may be
yielded to. In the latter case the abdominal muscles are forcibly
contracted, and the glottis being closed, the whole effect of their
contraction is expended in raising the pressure within the abdomen and
pelvis.... The sphincter ani is now relaxed by the inhibition of a
center in the lumbar portion of the spinal cord, through the activity
of which the tonic contraction of the sphincter is normally maintained.
This relaxation is partially voluntary, the impulses that come from
the brain acting probably through the medium of the lumbar center; but
in the dog, after section of the cord in the dorsal region, the whole
act of defecation, including contraction of the abdominal muscles and
relaxation of the sphincter, still takes place, and here the process
must be purely reflex. The contraction of the levatores ani helps to
resist overdistention of the pelvic floor and to pull the anus up over
the feces as they escape.”[16]
The above paragraph concisely represents the accepted interpretation of
the act of defecation. The rectal valve, an individual anatomic organ
in itself, must, however, be reckoned with in studying the operations
of the integral mechanism of defecation.
DIGITAL OBSERVATION OF THE NONANESTHETIZED SUBJECT.
In the normal rectum, when the first rectal valve can be reached by
the finger, provided it be immediately discovered on the introduction
of the finger, a definite but not rigid band of tissue may be felt
buried behind the masses of lax mucosa. This band presents at one side
that which seems to be a circular aperture of variable diameter; a few
seconds’ application of the passive finger detects a gradual relaxation
of what first had seemed a ring-like constriction till the finger can
make out but an indefinite thickening on a side of the gut-wall. If
the finger be held passive, this constriction may again surround the
finger; but if so, it does so with a somewhat weaker grasp. Often the
presence of the finger within the rectum excites a peristalsis-like
contraction, during which the valve usually cannot be detected. When
the rectum is filled with water, the valve is sometimes more readily
discoverable by the finger, and when discovered, the diameter of the
valve-strait is greater than that before noticed, and the grasping
tendency of the valve is not so noticeable.
OCULAR OBSERVATION OF THE ANESTHETIZED SUBJECT.
If a somewhat emaciated male be selected, one whose rectum is
susceptible to atmospheric inflation while in the lithotomy posture,
and if the large intestine be freed of its contents, if such a subject
be anesthetized and his colon or sigmoid filled with water, and the
anus divulsed and held open with the speculum, the water confined to
the rectum may be bailed out, and the rectum will then be seen to
present the multichambered condition already described. If the inquirer
will now place a hand on the abdomen over the sigmoid flexure, and
give the part a quick, firm pressure, his watchful eye may observe a
downward rush of waters into the rectum, first striking the concave
wall formed by the juncture of the upper surface of the uppermost
visible valve and the adjoining rectal wall, bounding from this surface
to the opposite next lower valve, from which the stream is deflected
to a lower point on the opposite wall, by which time all may be
obscured by a wave of contracting peristalsis, rhythmically repeated,
which may project small quantities of water through the anus. In the
intervals of the contractions, the rectal chambers are observed to be
either submerged or else atmospherically inflated.
OCULAR OBSERVATION OF THE NONANESTHETIZED SUBJECT.
If a subject under proctoscopy be directed to bear down, it is
observable that the empty and atmospherically inflated rectum closes
under the compression of the voluntary forces by the concave anterior
wall becoming convex, and being carried backward toward the fixed
posterior wall, the transverse diameters remaining apparently but
little shortened. The compression may be noticed as being applied from
before and in a backward direction, and simultaneously from above
downwardly. In case firm fecal masses, or lubricated balls of cotton
experimentally placed, are dejected by these efforts, there will be
noticeable depression of the valve-floor under the pressure of the
descending mass. Presently the mass will appear at the valve-edge,
where it may seem suspended for a few seconds before it is plunged on
into the next lower chamber. Occasional rhythmic contractions of the
rectal muscular coats occur, which fill and transitorily obscure the
field under observation with masses of the reduplicated mucosa, and
it is always possible to note that such contractions have changed the
positions of the gut’s contents.