Leonardo da Vinci - the anatomist (1930) 16
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McMurrich JP. Leonardo da Vinci - the anatomist. (1930) Carnegie institution of Washington, Williams & Wilkins Company, Baltimore.
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Leonardo da Vinci - The Anatomist
Chapter XVI The Excretory and Reproductive Organs
To the classical and mediaevel anatomists the kidneys were solid masses of parenchyma to which a plentiful supply of blood was brought by the emulgent (renal) veins, and from this blood the parenchyma by its attractive faculty (Galen) extracted the superfluous aquosity. The kidneys, therefor, disposed of the third of the triad of superfluities, yellow bile, black bile and aquosity, engendered in the liver during the concoction of blood from chyle.
Leonardo’s views as to the anatomy and physiology of the kidneys are essentially these. He did recognize, however, the need for a further study of the structure of the organs and especially of the arrangement of the vessels in the parenchyma, and suggested that the study might be facilitated by boiling the kidney (Q III, 3). But there is no indication that he carried out the investigation. On AnB, 13v he proposes to cut the kidney in half to show how the paths of the urine contract and how it is distilled, having apparently observed the renal pyramids later described by Malpighi. Ilis figures of the kidney far surpass in accuracy contemporary illustrations, even though a suspicion may be entertained that they were based on animal preparations, a suspicion that is strengthened by the fact that when both kidneys are represented the left is a little lower than the right (fig. 53), a condition found in many animals but unusual in man. It is noted (QII, 7) that the kidneys, together with the ureters, the great vein (vena cava) and the emulgent veins, are retroperitoneal.
The only note bearing on the physiology of excretion is to the effect that the quantity of urine is an index to the quantity of blood passing to the kidneys, some of the blood first passing through the heart, though the greater part descends by the vena cava without traversing the heart (QI, 10).
The ureters arc shown in several figures as slender gently curved tubes of uniform caliber, opening into the bladder at about half its height (fig. 69). The manner in which they traversed the wall of the bladder is discussed at some length in two passages (AnB, 14 and 37). The opinion of earlier authors that they traversed the bladder wall obliquely is mentioned, and the arrangement is regarded as a provision of Nature to prevent a backward flow toward the kidneys, since the pressure of the urine on the bladder wall would occlude the ureteric pores when it had reached a level a little above them. Leonardo finds this reasoning defective for, since the ureters open into the bladder at about half its height and since occlusion of their openings would prevent the entrance as well as the exit of urine, the bladder could never become more than half full. Half its capacity would be useless, a superfluity, and Nature never permits superfluities! Further it is argued that in the erect position the urine can not rise in the ureters above its level in the bladder, but if one is standing on one’s head it might pass back to the kidneys. This latter posture, however, as Leonardo quaintly suggests, is not often assumed. Lying on the side the ureteric pore of that side will be closed by the pressure of the urine, but the other will continue to convey fluid to the bladder ; while if one lies prone both pores can admit urine until the bladder is filled. He meets the suggestion that the more the bladder is distended the greater will be the compression of the intramural portions of the ureters, resulting in stoppage of the entrance of urine into the bladder, by assuming that the newly produced, subtle and high ( sottile e alta ) urine is more powerful than the low and large ( bassa e larga) that is in the bladder.
Fig. 60. The male organs of reproduction. (QIII, 4.)
On folios AnB, 14 and 37 are illustrations of another mode of passage of the ureter through the bladder wall. On penetrating the outer coat of the bladder the ureter bends sharply on itself and runs upward for some distance, gradually passing through the successive coats. This is pure imagination and does not harmonize with the statement on AnB, 37, that the ureter enters the bladder “by small perforations made transversely between the coats.” One is inclined to believe that Leonardo had never opened the bladder to observe its interior.
The bladder is always represented in a fully distended condition, almost globular in form (fig. 69), and in some instances veins and arteries are shown ramifying over its surface (AnB, 37). That its walls are formed of several layers is implied, but no description of these is given. On QIII, llv there is a memorandum “where the neck of the bladder shuts and why?” but the inquiry remained unanswered, although there is another memorandum to describe “the nerves, or one may say the muscles, that shut the gate of the bladder” (QIV, 11).
Leonardo’s ideas regarding the reproductive organs present a curious commingling of accurate observation with acceptance of tradition. Never before had the organs been represented so accurately as to form, but the influence of tradition as to function led to inaccuracies in detail and, what is more remarkable, to the portrayal of structures that had no real existence. It seems probable, however, that those drawings in which tradition is most in evidence belong to the earlier periods of his studies.
In the double folio QI, 12 (fig. 70), Leonardo represents his idea of the female internal organs of generation, based apparently partly on observation, for his representation is far more accurate than those of any of his predecessors, and partly on preconceived notions gained from earlier authors. The uterus, somewhat exaggerated as to size, is shown as a broad pyriform structure, to each of whose sides there are attached, at about the middle of its length, two cylindrical processes, one of which is directed upward and outward and the other outward and slightly downward, almost parallel with the external iliac vessels. The upper process probably represents the tuba uterina and the lower the round ligament of the uterus, but of neither is a description given. Leonardo may be assumed to have been ignorant of the purpose of the tubce uterinae; Mondino does not mention them and Avicenna’s description of them is exceedingly obscure and the function he ascribed to them altogether inaccurate. It is to Leonardo’s credit that he should observe and portray them even imperfectly and still more to his credit that he should be the first to figure the round ligaments.
Lower down, opposite the middle of the length of the cervix, are two broadly fusiform structures to which blood-vessels descend from above. These are evidently the ovaries, or, as Leonardo, following earlier examples, calls them, the testicles ( testicholi ). They are, of course altogether too low in position and each is connected with the cervix by a short cylindrical structure which, if it were higher, might be taken to be the ovarian ligament, but it is much more probably intended for a duct, by which the ovary may communicate with the cavity of the uterus. For Leonardo held the common belief that there was a female sperm as well as male sperm, and that it was formed from the blood brought to the ovary by the ovarian vessels, receiving its generative virtue in the ovaries and thence passing to the uterus where it was stored, its generative virtue being called into activity, however, only when it was mingled with the male sperm (QIV, lv). That it was stored in the uterus demanded a communication between the ovary and that organ and this communication Leonardo supplied.
On QIII, 7 the uterus is again figured and this time it is almost triangular in outline, and from the upper angle on each side the three structures shown on QI, 12 (fig. 70) arise. The upper structures may be taken to be the tubre uterinae, the middle ones the round ligaments, here sadly displaced since they are directed upward toward the kidneys, while the lower structures represent the ovaries as fusiform enlargements with the ovarian vessels descending to them from above and with a short duct connecting them with the uterus and strongly suggesting the ovarian ligament. Neither in this figure nor in that on QI, 12 is there any indication of the anteflexion of the uterus, but in four figures on QIII, lv the long axis of its body is approximately at right angles with that of the vagina.
The classical authors, basing their ideas on the dissection of animals, describe the uterus either as bifid or as containing two cavities, and in the Middle Ages, under the influence of the Salernitan School and its dissection of the pig, it was a common belief that it was a seven-chambered structure ; so it was described by Mondino, so it was figured in the Anatomie of Guy de Vigevano (1345) and in the Antropologium of Magnus Hundt (1501). The extreme teleological views of their times led to the doctrine that in any animal the uterus would contain as many chambers as there were mammary glands, and Avicenna found support for his statement that the human uterus was bilocular in the fact that the mammary glands are two in number. The bilocular theory died hard; it was maintained by Berengar da Carpi as late as 1535, he associating with it the ancient theory of sex-determination, to the effect that the infant developing in the right chamber would be a male, and that from the left chamber a female. On QIII, 7 are two figures showing the cavity of the uterus and in both that cavity is single. For Leonardo the human uterus was a uterus simplex, a fact that became generally accepted after the publication in 1543 of Vesalius’ De Fabrica.
Fig. 70. The female organs of reproduction. (QI
In the case of the male organs, the mingling of clear observation and reliance on tradition is even more distinctly shown. The testes are shown in a number of figures as oval bodies (fig. 69), each contained within a scrotal sac and surmounted by a coiled apparatus, this representing the epididymis and being formed partly by the terminal portions of the spermatic vessels and partly by the beginnings of the ductus deferens. The course of the ductus is correctly shown, passing upward over the pubic bone and then curving backward to the back of the bladder, where it seems to dilate into a somewhat corrugated sac, the seminal vesicle ( spermatic ventricle, QIV, 11), and beyond this it is continued forward to open into the proximal portion of the urethra. It is curious that the prostate gland is neither mentioned nor figured ; it was probably regarded as merely flesh ( caro ), hardly worthy of notice.
The idea that the spermatic vessels formed an important part of the epididymis was based on the belief that the male sperm, like that of the female, was formed directly from the blood, receiving its third and final concoction (QIII, lOv) and its germinal virtue from the testes, wflience it passed to the seminal vesicles which served as reservoirs for it (QIII, lv). Other theories as to the function of the testes are disputed, such as that of Mondino which assigned to the seminal vesicles and testes merely the production of a saliva-like humor intended for the delectation of the female during coition (QI, 12) ; and another that the testes might occlude or, by retraction, open the mouths of the seminal vesicles and so prevent or permit the emission of sperm (QII, 17).
But Leonardo was not always so sure as to the function of the testes, for on QIII, 3v, there is a memorandum to enquire as to what the testes ( coglioni ) have to do with coition and with the sperm, and another to enquire why the testes are the cause of ardor. On AnB, 13
this last query is definitely answered, the organs being held to be the seat of emotion, the proof being found in the fact that bulls, rams, boars and cocks, all very fierce creatures, become cowardly when castrated, so that a flock of castrates may be chased away by a single ram and a number of capons by a single cock.
But these queries are not the only indications of uncertainty; he also figures structures that are altogether imaginary and which he had found mentioned by older authors. QIII, 3v is the folio on which is the coition figure and in this two canals are represented traversing the intromittent organ, a lower one which communicates with the bladder and therefore serves for the passage of urine, and an upper one that gives passage to the sperm. These canals are more precisely shown in two other figures of the same folio, one representing a longitudinal and the other a transverse section of the male organ (fig. 59). The idea of a special canal for the sperm may have been obtained from Mondino; Avicenna describes three penial canals, a meatus urinarius, a meatus spermatis and a meatus alquadi.
Another peculiarity of the coition figure may be noted. The spinal cord is represented as extending to the very tip of the spinal canal and in the sacral region a stout nerve arises from it by three roots. It passes over the side of the bladder and is continued onward to the tip of the penis, forming the spermatic canal of that organ, the nerves being regarded as hollow tubes. This imaginary nerve seems to trace back to an ancient Greek theory that the medulla spinalis was concerned in the formation of the sperm; in a figure on QY, 21 the spinal cord is labeled “virtu genitiva.” In the Hippocratic treatise De semine the origin of the sperm is said to be from all four humors and also from all the solid parts, the fluid so formed passing to the spinal cord and thence to the testes. AYhence Leonardo got this idea is uncertain; it was not from Avicenna, who is inclined to assign the ultimate origin of the sperm to the brain, whence it passed downward through veins that run behind the ears. Leonardo, however, later relinquished the idea of the nervous system as the origin of the sperm, regarding it as a final concoction of the blood in the testes, a view which is strictly Galenic.
It was a common belief in the Middle Ages that the uterus possessed a certain amount of individuality independent of that of the body, and could at its own volition leave its proper place, thereby producing a series of symptoms known as the passio hysterica. Similarly on account of its involuntary behavior, an amount of individuality was attributed to the male organ and both Plato and Aristotle speak of it as being to some extent an independent animal. Leonardo was sufficiently mediaeval to accept this idea; “This animal'’ he says of it “often has a soul and intellect apart from the man” (AnB, 13). But while he was mediaeval in this idea he was decidedly modern in his view as to the cause of the occasional turgidity of the organ. The ancients and, following them, both Avicenna and Mondino, ascribe the turgescence to the organ becoming inflated by a “ventosity,” but Leonardo disputed this idea, claiming that it was due to the organ becoming replete with blood. For he had observed that many persons, and especially those who are hanged (QIII, 7), die with the organ in erection, and in an Anatomy of such an one that he witnessed the organ was full of blood, so that the tissue was very red in color (AnB, 2v).
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Reference: McMurrich JP. Leonardo da Vinci - the anatomist. (1930) Carnegie institution of Washington, Williams & Wilkins Company, Baltimore.
Cite this page: Hill, M.A. (2020, September 26) Embryology Leonardo da Vinci - the anatomist (1930) 16. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Leonardo_da_Vinci_-_the_anatomist_(1930)_16
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