Part 4
In the passive subject the finger discovers the ectal sphincter as a 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 diameter be introduced through the fixed rectum and then withdrawn through the levator ani to a point above the ental sphincter and the patient be directed to contract the muscles of the pelvic floor, it may be observed that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.
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.
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.