CHAPTER I. PRACTICAL POINTS IN ANATOMY AND PHYSIOLOGY. (Part 1)

CHAPTER I. PRACTICAL POINTS IN ANATOMY AND PHYSIOLOGY. Tue rectum is the terminal portion of the large intestine ex- tending from the sigmoid flexure to the anus. In its natural position its length varies in different persons from six to eight inches. When dissected out of the body and straightened, it will be found to measure about two inches more. Its position in the true pelvis is comparatively fixed, and its fixity renders it the more liable to those displacements, such as invagination and prolapse, which are due to straining at stool ; and accounts also for the fact that, when denuded by the destruction of the surrounding cellular tissue, it remains separated from the walls of the pelvis, and cannot come in contact with the adjacent soft parts and thus undergo healing. The upper limit of the rectum is difficult to determine with accuracy, except from the fact that it is separated from the sig- moid flexure by a slight constriction which becomes more ap- parent when attempts are made at dilatation. From this upper point it gradually expands below into a pouch, the ampulla, and then again suddenly contracts under the grasp of the muscles which close its lower end. Curves.—The curves of the rectum are exceedingly important in a practical point of view. There are two, one antero-pos- terior, the other lateral. The former is double. From above downward it follows the curve of the sacrum and coccyx, being ‘concave in front and convex behind. When it reaches a point 1 2 DISEASES OF THE RECTUM AND ANUS. opposite the tip of the coccyx, it suddenly reverses its direction, turns sharply backward, and ends at the anus about one inch in front of the tip of that bone. By this backward curve of its lower end, which is repre- sented in an exaggerated form in Fig. 1, it is separated from the vagina in the female, and from the urethra in the male, by a triangular space having its base at the perineum, its upper wall at the vagina or urethra, and its lower at the upper wall of the rectum. The angle of junction of these two curves is well marked, measuring from twenty to thirty degrees; and the curve is not without influence in the function of defecation, Fic. 1—Exaggerated Antero-posterior Curve of the Rectum. since, by the feeces. The lateral cur it, an obstruction is formed to the downward course of a single one from left to right, starting at the left sacrc synchondrosis and ending at the median line at a point oppo te ‘the third sacral vertebra, from which point it generally passes straight on to the anus. This curve may, however, pass beyond thé median line to the right in its lower portion, and again return to the median line at the anus. It is subject to many variations, and the upper portion may be more or less twisted on itself like the sigmoid flexure. The sigmoid flexure may occupy an unnatural position, and the rectum, instead of commencing at the left sacro-iliae junc- is general]. °. POINTS IN ANATOMY AND PHYSIOLOGY. 3 tion and curving toward the right, may commence at the right and curve toward the left. In one case, reported by Cruveil- hier,’ where the sigmoid fiexure was in the natural position, the rectum passed almost transversely to the right side as far as the right sacro-iliac junction, and then returned again very obliquely to the left side. Divisions.—For convenience of description the rectum is usu- ally divided into three portions, named first, second, and third, from above downward. The third extends from the anus to the tip of the prostate, is about an inch and a half long, is firmly closed by the sphincters, and gives attachment to a portion of the levator ani muscle. On account of the direction of this por- tion, which is the reverse of that next above, the finger should never be passed toward the sacrum, or even directly inward, in making an examination ; but rather toward the pubes. Bearing this simple anatomical point in mind will often save the patient much unnecessary suffering. The second portion is often de- scribed as reaching from the apex of the prostate to the recto- vesical fold of peritoneum ; but, as the point of duplicature of the peritoneum is not only variable in different individuals, but at different times in the same individual, it is better to adopt a fixed bony point, as the third piece of the sacrum ; in which case the middle portion will measure about three inches in length. This portion, it will be remembered, is convex backward, following the curve of the sacrum. The first portion extends from the third sacral vertebra to the left sacro-iliac synchondrosis ; its lower part is partially, and its upper completely, surrounded by peritoneum, which, in the upper part, forms the meso-rectum attaching it to the sacrum. Nore.—Treves (‘‘ The Anatomy of the Intestinal Canal,” etc., 1885), as the result of one hundred dissections, denies this arrangement of the first or upper part of the rec- tum. He says: “The segments of gut termed the sigmoid flexure and the first part of the rectum form together a single simple loop that cannot be divided into parts. ‘This loop begins where the descending colon ends, and ends at the commencement of the so-called second piece of the rectum—at the spot, in fact, where the meso-rectum ceases, opposite about the third piece of the sacrum, This loop when unfolded de- scribes a figure that, if it must be compared to a letter, may well be compared to the capital Omega. If at any time new terms should be introduced, it might be well to call all that segment of the bowel between the ending of the descending colon and the ending of the meso-rectum the omega loop, and to limit the term ‘rectum’ to the short piece of practically straight gut that is now described as the second and third parts of the rectum.” Relations.—The most important surgical relations of the rec- 1 “Anat. Path.,” Amer. Edition, 1844, p, 877. 4 DISEASES OF THE RECTUM AND ANUS. tum are on the anterior surface. The third portion is sur- rounded laterally and posteriorly by a bed of connective tissue rich in fat and blood vessels, and may, therefore, be incised on either side, or backward, with comparative safety. In front, however, it is directly in relation with the membranous urethra. in the male, and with the vagina in the female ; though at the anus it is separated from them both by its backward and down- ward course. This intimate relationship with the urethra is often taken advantage of in catheterism, when by passing the finger into the rectum the tip of the instrument may easily be felt ; and it also explains why in all operations on the urethra or vagina the rectum should first be emptied to save it from being wounded. In the second portion, also, the lateral and posterior surfaces have no special surgical relations ; while the anterior is in direct contact with the prostate, the base of the bladder, the seminal vesicles, and sometimes, at its upper limit, with the peritoneal fold of Douglas. This portion is closely connected with the bladder in the male, and with the vagina in the female, by con- nective and muscular tissue ; and the two cavities may easily be made to communicate by any morbid process or by a sur- gical procedure. It was at this point that the trocar was plunged from the rectum into the bladder in the old operation of punc- turing the bladder through the rectum ; and Hyrtl’ speaks of a man who was only able to pass his water after first introducing his finger into the rectum and raising a calculus out of the tri- gone of the bladder. A somewhat analogous case is reported in which a long, slender calculus perforated the bladder and pro- jected into the rectum, from which it was easily removed.* The prostate, when large, may project over the sides of the rectum, or the latter ma. sive the prostate in a groove on its upper surface. The first, or upper portion, unlike the other two, has impor- tant surgical relations on every side. Posteriorly it is in whole or part covered with peritoneum, and is separated from the sa- crum by the pyriformis muscle, the sacral plexus of nerves, and the branches of the internal iliac artery. On its sides it is in contact with the adjacent convolutions of small intestine, and lower down, with the levator ani muscle and the connective tis- sue of the ischio-rectal fossa. In the male it is in relation, in front, with the posterior surface of the bladder, from which it Anat.,” ii., p. 10 Chirurg. Works, ' «Topog, * Gooch : London, 1792, vol. iii., p. 216. POINTS IN ANATOMY AND PHYSIOLOGY. 5) is separated by coils of small intestine. In cases of retention, either of urine or feeces, the two may be brought into actual contact. In the female it is in relation, anteriorly, with the broad ligament, the left ovary and Fallopian tube, the uterus and vagina. When the rectum and uterus are empty, the coils of small intestine pass down between them to the bottom of the fold of Douglas, and they may even escape through the posterior wall of the vagina in case of injury. From these relations it is apparent that enlargements and malpositions of the uterus must act directly upon the rectum. Fi, 2.—(After Henle.) Horizontal Section through Urethra, Vagina, and Anus. (The anus considered as about an inch long, and including the terminal portion of the rectum.) The vessels may be so obstructed by uterine disease as to cause hemorrhoidal troubles, or interfere with operations for their re- lief. The rectum may be entirely occluded by the pressure of a uterine tumor ; and a hasty examination of the rectum may lead to the diagnosis of a tumor in its anterior wall, when in reality the normal uterus alone is felt. The advantage of a rectal exam- ination in all doubtful cases of pelvic disease is also manifest. The Anus.—The rectum terminates below in the anus, which is tightly closed by the external sphincter muscle. The skin around its border is thin and pigmented, covered with fine hair 6 DISEASES OF THE RECTUM AND ANUS. in the male, and contains a great number fof sebaceous follicles and muciparous glands. The skin passes deeply into the anal orifice, and its point of junction with the mucous membrane is in some persons indicated by an indistinct white line.‘ This white line of junction also corresponds to the division between the external and internal sphincter muscles; and also to the point at which many of the terminal filaments of: the internal pudic nerve perforate the gut. Both skin and mucous mem- brane at the anus are remarkable for the development of erec- tile tissue ; the arteries coming from the inferior heemorrhoidal, and the veins being very numerous, winding, and twisted. After these general considerations of the position and rela- tions of the rectum as a whole, the individual parts may be taken up more in detail. The rectal wall is composed, as are the other parts of the intestine, of four layers: an external or peritoneal ; a muscular, divided into longitudinal and circular ; a submu- cous connective tissue layer; and, most internally, the mucous membrane. The total thickness of these coats collectively varies greatly in different subjects, the variation being chiefly in the muscular coat, the others remaining pretty constantly of the same thickness. Peritoneuin,—The upper portion of the rectum is entirely sur- rounded by peritoneum, and has, besides, a fold of attachment to the anterior face of the sacrum, known as the meso-rectym. The meso-rectum is about four inches long, blends with the meso-colon above, and extends down as low as the third or fourth sacral vertebra, from which point its two layers are re- flected over the sides and anterior surface of the rectum on to the posterior wall of the uterus and upper limit of the vagina in the female ; and upon the bladder in the male, forming the cul-de-sac of Dougla The meso-rectum may be so short as to disappear when the rectum is distended, or it may be entirely absent ; in which case the peritoneum passes directly from the sides of the rectum to the sacrum. Between its two layers may be found some loose connective tissue, the heemorrhoidal vessels and the lymphatics. In passing from the third piece of the sacrum behind to form the cul-de-sac in front, the peritoneum coyers more or less of the Jateral and anterior surfaces of the middle portion of the rec- tum, As before mentioned, the point at which the peritoneum Jeaves the anterior surface of the middle portion of the rectum, to be reflected upon the posterior surface of the bladder in the ‘Milton : ‘* Rest and Ps POINTS IN ANATOMY AND PHYSIOLOGY. 7 male, or of the vagina or uterus in the female, varies in dif- ferent subjects, and at different times in the same subject ; and hence the differences in its distance from the anus as given in different works on anatomy. In new-born children the bottom of the cul-de-sac touches the upper edge of the prostate and ap- proaches to within about an inch of the anus. At five years it rises in the pelvis with the development of the seminal vesicles and internal organs of generation ; and in old people with en- largement of the prostate itis carried still higher. In women it generally covers the upper part of the posterior vaginal wall, so that the latter is separated from the rectum by peritoneum for about one-third of an inch. By every expansion of the blad- der or rectum, as well as by tumors of the pelvis, the fold is carried further away from the anus, as may easily be demon- strated on the cadaver by forcible injections of the bladde: The average distance from the anus to the point at which the serous coat leaves the anterior wall of the rectum is, therefore, very difficult to determine. Dupuytren gives the distance as seventy mm., and less when the organs are empty ; Lisfranc gives six inches in the female, and four in the male, but does not state in what condition of the organs the measurements are taken; Sappey, Velpeau, and Legendre give five and a half em. when the bladder is empty and eight when distended ; Quain says four inches ; Allingham from two to five or more. Cripps,’ acting on the idea that the fold is not easily displaced downward by traction on the rectum, has experimented by fill- ing the peritoneal cavity with plaster, and then thrusting a needle through the skin of the perineum till its point struck the plaster. In this way he has obtained an average measure- ment of two and a half inches when the bladder and rectum are both empty, and an additional inch when distended.* Muscular Coat,—In the fact that the muscular coat is ar- ranged in two layers, an external longitudinal and an internal circular, the rectum resembles the other portions of the alimen- tary canal; but in the further arrangement of its fibres it resem- bles the cesophagus more closely than the intermediate portions. The fibres are spread out into two uniform layers, and are not 1 “Cancer of the Rectum,” London, 1880, p. 129. 2The following authors give the following measurements : 2, males, 6-8 cm. ; females, 4-6 cm. Luschka, 5.5-8 cm, Lyrtl, Sem. a San- son, 11cm, Richet, males, 10.8 cm.; females, 16.2cm. Blaudin, males, 8.1 em. ; females, 4.1 em, Ferguson, males, 10.5 cm. ; females, 15.4 cm. Esmarch: “Die Krankheiten des Mastdarms und des Afters.” Pitha u, Billroth ; “Chirurgie,” p. 7. 8 DISEASES OF THE RECTUM AND ANUS. . arranged in bands crossing each other in basket network and leaving sacculi between the meshes as in the large intestine. The longitudinal fibres are the direct continuation of the _three longitudinal bands of the large intestine. Upon reaching the rectum, these blend into one continuous sheath which, how- ever, is somewhat heavier on the anterior surface of the bowel than on any other. At the point of contact of the rectum with the bladder and prostate, these fibres are in part reflected with the peritoneum on to the posterior wall of the latter, and thus form a firm band of union between the two organs, as has been particularly described by Dr. Garson.’ They have been named by him the recto-vesical fibres, but I have never been able to es- tablish the fact of their existence. The ending of the longitudinal fibres is worthy of note. Ac- cording to Horn: when they reach the lower margin of the in- ternal sphincter a part of them turn upward between it and the external sphincter, and ascend for an inch or two in contact with the mucous coat, into which they are finally inserted ; hav- ing, therefore, an obvious influence in causing protrusion of the mucous membrane. In the lower fourth of their extent, these fibres become weaker and less distinct, and some of them finally blend into elastic tendinous tissue which passes between the bundles of the external sphincter, and is inserted into the subcutaneous connective tisstte of the anus. Others are inserted posteriorly, by means of an elastic tendon about an inch long, into the anterior sacro-coccygeal ligament—an arrangement pointed out by Luschkz analogous to what is found in most mammalia, in whom a considerable number of the longitudinal fibres are inserted into the base of the coccyx, giving a fixed point for the rectum in defecation. The circular layer is reinforced at certain points,