Surgical Anatomy Part 39

[Ill.u.s.tration: Abdomen, showing blood vessels and other internal organs.]

Plate 55--Figure 2

Fig. 3, Plate 55.--The membranous urethra A is also in some instances embraced by two symmetrical fasciculi of muscular fibres B B, which arising from the posterior and lower part of the symphysis pubis, descend on either side of the ca.n.a.l and join beneath it. The muscles B C, Fig. 2, Plate 55, are between the two layers of the deep perinaeal fascia, while the muscle B B, Fig. 3, Plate 55, lies like the forepart of the levator ani, C C, behind this structure and between it and the anterior ligaments of the bladder. [Footnote] As to the interpretation of the muscle, I, myself, am inclined to believe that it is simply a part of the levator ani, and for these reasons--1st, it arises from the pubic symphysis, and is inserted into the perinaeal median line with the levator ani; 2nd, the fibres of both muscles overlie the forepart of the prostate, and present the same arrangement in parallel order; 3rd, the one is not naturally separable from the other.

[Footnote: This is the muscle, B B, which is described by Santorini as the "levator prostatae;" by Winslow as "le prostatique superieur;" by Wilson as the "pubo-urethrales;" by Muller as not existing; by Mr.

Guthrie as forming (when existing), with the parts B C, Fig. 2, Plate 55, his "compressor isthmi urethrae;" and by M. Cruveilhier as being part of the levator ani muscle. "As in one case," (observes Mr. Quain,) "I myself saw a few vertical muscular fibres connected with the transverse compressor, it has been thought best to retain the muscle in the text."--Dr. Quain's Anat., Am. Ed. vol. ii. p. 539.]

[Ill.u.s.tration: Abdomen, showing blood vessels and other internal organs.]

Plate 55--Figure 3

Fig. 1, Plate 56, represents by section the natural forms of the urethra and bladder. The general direction of the urethra measured during its relaxed state from the vesical orifice to the glans is usually described as having the form of the letter S laid proc.u.mbent to the right side [capital S rotated 90 degrees right] or to the left [capital S rotated 90 degrees left]. But as the anterior half of the ca.n.a.l is moveable, and liable thereby to obliterate the general form, while the posterior half is fixed, I shall direct attention to the latter half chiefly, since upon its peculiar form and relative position depends most of the difficulty in the performance of catheterism. The portion of the urethra which intervenes between the neck of the bladder, K, and the point E, where the p.e.n.i.s is suspended from the front of the symphysis pubis by the suspensory ligament, a.s.sumes very nearly the form of a semicircle, whose anterior half looks towards the forepart, and whose posterior half is turned to the back of the pubis. The pubic arch, A, spans crossways, the middle of this part of the urethra, G, opposite the bulb H. The two extremes, F K, of this curve, and the lower part of the symphysis pubis, occupy in the adult the same antero-posterior level; and it follows, therefore, that the distance to which the urethra near its bulb, H, is removed from the pubic symphysis above must equal the depth of its own curve, which measures about an inch perpendicularly. The urethral aperture of the triangular ligament appears removed at this distance below the pubic symphysis, and that portion of the ca.n.a.l which lies behind the ligament, and ascends obliquely backwards and upwards to the vesical orifice on a level with the symphysis pubis in the adult should be remembered, as varying both in direction and length in individuals of the extremes of age. In the young, this variation is owing to the usual high position of the bladder in the pelvis, whilst in the old it may be caused by an enlarged state of the prostate. The curve of the urethra now described is permanent in all positions of the body, while that portion of the ca.n.a.l anterior to the point F, which is free, relaxed, and moveable, can by traction towards the umbilicus be made to continue in the direction of the fixed curve F K, and this is the general form which the urethra a.s.sumes when a bent catheter of ordinary shape is pa.s.sed along the ca.n.a.l into the bladder. The length of the urethra varies at different ages and in different individuals, and its structure in the relaxed state is so very dilatable that it is not possible to estimate the width of its ca.n.a.l with fixed accuracy. As a general rule, the urethra is much more dilatable, and capable consequently of receiving an instrument of much larger bore in the aged than in the adult.

The three portions into which the urethra is described as being divisible, are the spongy, the membranous, and the prostatic. These names indicate the difference in the structure of each part. The spongy portion is the longest of the three, and extending from the glans to the bulb may be said on a rough, but for practical purposes, a sufficiently accurate estimate to comprise seven parts of the whole urethra, which measures nine. The membranous and prostatic portions measure respectively one part of the whole. These relative proportions of the three parts are maintained in different individuals of the same age, and in the same individual at different ages. The spongy part occupies the inferior groove formed between the two united corpora cavernosa of the p.e.n.i.s, and is subcutaneous as far back as the s.c.r.o.t.u.m under the p.u.b.es, between which point and the bulb it becomes embraced by the accelerator urinae muscle. The bulb and glans are expansions or enlargements of the spongy texture, and do not affect the calibre of the ca.n.a.l. When the spongy texture becomes injected with blood, the ca.n.a.l is rendered much narrower than otherwise. The ca.n.a.l of the urethra is uniform-cylindrical. The meatus is the narrowest part of it, and the prostatic part is the widest. At the point of junction between the membranous and spongy portions behind the bulb, the ca.n.a.l is described as being naturally constricted. Behind the meatus exists a dilatation (fossa navicularis), and opposite the bulb another (sinus of the bulb).

Muscular fibres are said to enter into the structure of the urethra, but whether such be the case or not, it is at least very certain that they never prove an obstacle to the pa.s.sage of instruments, or form the variety of stricture known as spasmodic. The urethra is lined by a delicate mucous membrane presenting longitudinal folds, which become obliterated by distention; and its entire surface is numerously studded with the orifices of mucous cells (lacunae), one of which, larger than the rest, appears on the upper side of the ca.n.a.l near the meatus. Some of these lacunae are nearly an inch long, and all of them open in an oblique direction forwards. Instruments having very narrow apices are liable to enter these ducts and to make false pa.s.sages. The ducts of Cowper's glands open by very minute orifices on the sides of the spongy urethra anterior to and near the bulb. On the floor of the prostatic urethra appears the crest of the veru montanum, upon which the two seminal ducts open by orifices directed forwards. On either side of the veru montanum the floor of the prostate may be seen perforated by the "excretory ducts" of this so-called gland. The part K, which is here represented as projecting from the floor of the bladder, near its neck, is named the "uvula vesicae," (Lieutaud.) It is the same as that which is named the "third lobe of the prostate," (Home.) The part does not appear as proper to the bladder in the healthy condition, Fig. 2, Plate 56. On either side of the point K may be seen the orifices, M M, of the ureters, opening upon two ridges of fibrous substance directed towards the uvula. These are the fibres which have been named by Sir Charles Bell as "the muscles of the ureters;" but as they do not appear in the bladder when in a state of health, I do not believe that nature ever intended them to perform the function a.s.signed to them by this anatomist. And the same may be said of the fibres, which surrounding the vesical orifice, are supposed to act as the "sphincter vesicae." The form of that portion of the base of the bladder which is named "trigone vesical" const.i.tutes an equilateral triangle, and may be described by two lines drawn from the vesical orifice to both openings of the ureters, and another line reaching transversely between the latter.

Behind the trigone a depression called "bas fond" is formed in the base of the bladder. Fig. 2, Plate 56, represents the prostate of a boy nine years of age. Fig. 3, Plate 56, represents that of a man aged forty years. A difference as to form and size, &c., is observable between both.

[Ill.u.s.tration: Abdomen, showing blood vessels and other internal organs.]

Plate 56--Figure 1, 2, 3

COMMENTARY ON PLATES 57 & 58.

CONGENITAL AND PATHOLOGICAL DEFORMITIES OF THE PREPUCE AND URETHRA.--STRICTURE AND MECHANICAL OBSTRUCTIONS OF THE URETHRA.

When any of the central organs of the body presents in a form differing from that which we term natural, or structurally perfect and efficient, if the deformity be one which results as a malformation, ascribable to an error in the law of development, it is always characterized as an excess or defect of the substance of the organ at, and in reference to, the median line. And when any of the ca.n.a.ls which naturally open upon the external surface at the median line happens to deviate from its proper position, such deviation, if it be the result of an error in the law of development, always occurs, by an actual necessity, at the median line. On the contrary, though deformities which are the results of diseased action in a central organ may and do, in some instances, simulate those which occur by an error in the process of development, the former cannot bear a like interpretation with the latter, for those are the effects of ever-varying circ.u.mstances, whereas these are the effects of certain deviations in a natural process--a law, whose course is serial, gradational, and in the sequent order of a continuous chain of cause and effect.

Fig. 1, Plate 57, represents the prepuce in a state of congenital phymosis. The part hypertrophied and pendent projects nearly an inch in front of the meatus, and forms a ca.n.a.l, continued forwards from this orifice. As the prepuce in such a state becomes devoid of its proper function, and hence must be regarded, not only as a mere superfluity, but as a cause of impediment to the generative function of the whole organ, it should be removed by an operation.

[Ill.u.s.tration]

Plate 57.--Figure 1.

Fig. 2, Plate 57, represents the prepuce in the condition of paraphymosis following gonorrhoeal inflammation. The part appears constricting the p.e.n.i.s and urethra behind the corona glandis. This state of the organ is produced in the following-mentioned way:--the prepuce, naturally very extensible, becomes, while covering the glans, inflamed, thickened, and its orifice contracted. It is during this state withdrawn forcibly backwards over the glans, and in this situation, while being itself the first cause of constriction, it induces another--namely, an arrest to the venous circulation, which is followed by a turgescence of the glans. In the treatment of such a case, the indication is, first, to reduce by gradual pressure the size of the glans, so that the prepuce may be replaced over it; secondly, to lessen the inflammation by the ordinary means.

[Ill.u.s.tration]

Plate 57.--Figure 2.

Fig. 3, Plate 57, exhibits the form of a gonorrhoeal phymosis. The orifice of the prepuce is contracted, and the tissue of it infiltrated.

If in this state of the part, consequent upon diseased action, or in that of Fig. 1, which is congenital, the foreskin be retracted over the glans, a paraphymosis, like Fig. 2, will be produced.

[Ill.u.s.tration]

Plate 57.--Figure 3.

Fig. 4, Plate 57, shows a form of phymosis in which the prepuce during inflammation has become adherent to the whole surface of the glans. The orifice of the prepuce being directly opposite the meatus, and the parts offering no obstruction to the flow of urine, an operation for separating the prepuce from the glans would not be required.

[Ill.u.s.tration]

Plate 57.--Figure 4.

Fig. 5, Plate 57.--In this figure is represented the form of the p.e.n.i.s of an adult, in whom the prepuce was removed by circ.u.mcision at an early age. The membrane covering the glans and the part which is cicatrised becomes in these cases dry, indurated, and deprived of its special sense.

[Ill.u.s.tration]

Plate 57.--Figure 5.

Fig. 6, Plate 57.--In this figure the glans appears protruding through the upper surface of the prepuce, which is thickened and corrugated.

This state of the parts was caused by a venereal ulceration of the upper part of the prepuce, sufficient to allow the glans to press through the aperture. The prepuce in this condition being superfluous, and acting as an impediment, should be removed by operation.

[Ill.u.s.tration]

Plate 57.--Figure 6.

Fig. 7, Plate 57.--In this figure is shown a condition of the glans and prepuce resembling that last mentioned, and the effect of a similar cause. By the removal of the prepuce when in the position here represented, or in that of Fig. 6, the organ may be made to a.s.sume the appearance of Fig. 5.

[Ill.u.s.tration]

Plate 57.--Figure 7.

Fig. 8, Plate 57, represents the form of a congenital hypospadias. The corpus spongiosum does not continue the ca.n.a.l of the urethra as far forwards as the usual position of the meatus, but has become defective behind the fraenum praeputii, leaving the ca.n.a.l open at this place. In a case of this kind an operation on the taliacotian principle might be tried in order to close the urethra where it presents abnormally patent.

[Ill.u.s.tration]

Plate 57.--Figure 8.

Fig. 9, Plate 57, represents a congenital hypospadias, in which the ca.n.a.l of the urethra opens by two distinct apertures along the under surface of the corpus spongiosum at the middle line. A probe traverses both apertures. In such a case, if the ca.n.a.l of the urethra were perforate as far forwards as the meatus, and this latter in its normal position, the two false openings should be closed by an operation.

[Ill.u.s.tration]

Plate 57.--Figure 9.