Leonardo da Vinci - the anatomist (1930) 10

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McMurrich JP. Leonardo da Vinci - the anatomist. (1930) Carnegie institution of Washington, Williams & Wilkins Company, Baltimore.

   Leonardo da Vinci (1930): 1 Introductory | 2 Anatomy from Galen to Leonardo | 3 Possible Literary Sources of Leonardo’s Anatomical Knowledge | 4 Anatomical Illustration before Leonardo | 5 Fortunes and Friends | 6 Leonardo’s Manuscripts, their Reproduction and his Projected Book | 7 Leonardo’s Anatomical Methods | 8 General Anatomy and Physiology | 9 Leonardo’s Canon of Proportions | 10 The Skeleton | 11 The Muscles | 12 The Heart | 13 The Blood-vessels | 14 The Organs of Digestion | 15 The Organs of Respiration | 16 The Excretory and Reproductive Organs | 17 The Nervous System | 18 The Sense Organs | 19 Embryology | 20 Comparative Anatomy | 21 Botany | 22 Conclusion | References | Glossary of Terms | List of Illustrations
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Leonardo da Vinci - The Anatomist

Chapter X The Skeleton

In no department of anatomy does Leonardo’s accuracy of observation and portrayal stand out more clearly and more certainly mark the initiation of a new period in the history of descriptive anatomy, than in his studies of the skeleton. Conventionalism reigned in osteological illustration before his time; he it was who first portrayed the parts of the human skeleton in the form and proportions that Nature has given them.

The researches of Professor Karl Sudhoff have brought to light a number of manuscript representations of the human skeleton dating back at least to the middle of the twelfth century, and if to these are added the printed illustrations of the latter part of the fifteenth century, one obtains an excellent idea of the state of osteological knowledge in the pre-Vincian period and a basis for an estimate of the value of Leonardo’s work.

The early illustrations may be arranged in three groups, that is to say, three types of representation of the skeleton may be recognized, each of which is to be found, with more or less modification, in various manuscripts or prints. The oldest of these types, so far as they are known, is that contained in the Five-Figure Series (see p. 41) and of these the oldest known example is in a manuscript of the Munich Hofbibliothek (No. 13002) written by a monk of the abbey of Priifling, near Regensburg, in the year 1158. 1 * Ill The figure (fig. 18) has the crouching posture characteristic of the Five-Figure Series and, like the other illustrations of the series, is highly conventionalized and inaccurate. One may note especially the indication of sutures in the cranium and the curious device employed to represent the full complement of teeth; the insufficient number of vertebrae; the diagrammatized sacrum; the crenulations of the sides of the body to represent the ribs; two bones, apparently, in the upper arm; no indication of the os innominatum; the trochanter, termed vertebrum, represented as a distinct bone; and the remarkable arrangement of the bones of the foot. Sudhoff is undoubtedly correct in supposing that such illustrations were made by persons with no intimate knowledge of the objects they were portraying, copying unintelligently an earlier drawing, and he is also correct in supposing that what is represented is based upon what might be revealed by a lemur or desiccated cadaver rather than an osteologieal preparation.

1 K. Sudhoff, Tradition und Naturbeobachtung in den Ilhistrationen medizinischer

Handschriften und Frxihdrucke vornehmlich des 15 Jahrhunderts, Studien zur Gesch. der Medizin., vol. 1, 1908.

Four 2 other representations of this type are known. The Munich manuscript Xo. 17403, written at the Monastery of Scheyern by the Monk Konrad circa 1250 (Sudhoff, ’07), shows a figure practically identical with the Prufling one, although the accompanying text differs somewhat, and a strong resemblance is shown by the bone-man of a manuscript of the Bodleian Library (Cod. e Mus, 19) 3 of about the middle of the fourteenth century, though here the cranial sutures and the teeth are omitted, a single bone is shown in the upper arm and the abdomen shows a highly conventionalized representation of the stomach, liver and intestines. The bone-man of the Ashmolean Cod. 399,* dating from 1292, closely resembles the Prufling figure, differing from it in a fearsome expression of the countenance and in the fact that seven ribs on one side and six on the other are clearly represented as curving toward the median line, though no sternum is shown nor are the ribs attached to the vertebrae. Finally in the library of the Prince von Lobkowicz at Raudnitz, Bohemia, there is a manuscript 5 with a figure practically identical with that of the Ashmolean, though with a much milder facial expression. The date of this mansucript is 1399, a century later than that of the Ashmolean.

The illustrations of the second type are also parts of series which in their general conventionalism and posture are very similar to the FiveFigure Series just considered. They differ, however, in certain particulars, the differences being especially noticeable in the cases of the osteologieal figures. Four of the six known figures illustrating this type are in Persian manuscripts dating from the fourteenth century, but these need not concern us here except to note that they indicate an oriental origin for these series. They had, however, reached the western world at an early date, for Professor Sudhoff has brought to light two European examples of them, also belonging to the fourteenth century.

One of these was found in Ms. D II. 1 1 of the Library of the University of Basel 15 and is accompanied by text written in the Provencal dialect; from it (fig. 19) the characteristics of the type may be perceived. The most striking peculiarity is that the skeleton is represented as seen from behind and the face is bent upward as if hinged upon the frontal bone. The bones of the cranium are much more fully, if still highly diagrammatically, indicated than in the type I figures, the legends mentioning the upper and lower maxilla, the cheek bone, the frontal and parietals (os lande i.e. laudce subpositum ) ; the occipital ( papillus = paxillus capitis ) and the mastoid process. A series of twenty-four vertebral bodies succeeds, of which seven are assigned to the neck and the series ends with a sacrum said to be composed of three bones. Thirteen pairs of ribs, each attached to a vertebral body are shown, but the uppermost is attached to the tenth vertebra and consequently the last three have their attachment to as many lumbars. The clavicle is shown, but no scapula, notwithstanding that the view is from the back; the humerus is shown as a slender bone, while the bones of the forearm are stout; the carpus is indicated and transverse lines on the digits indicate the phalanges. There is no os innominatum, but one finds the label anca (ilium) some distance down upon the thigh and scia (acetabulum) still farther down, while coxa (femur) is just above the knee, and the bone itself is not represented. The patella is shown and the two bones of the crus, but the bones of the foot are treated as sketchily as those of the hand. It would seem that the figure was copied from an earlier drawing by one unfamiliar with the parts he was endeavoring to represent.

5 Sudhoff lists five, i.c. six, in all, but one of these, the Dresden Cod. 310, will be considered later.

3 K. Sudhoff, Drci xccitcrc analomischc F linfbildcrsericn aus Abendland und Morgenland, Arch, fiir Gesch. d. Medizin, vol. 3, 1910.

K. Sudhoff, Wciterc Bcilriigc zur Geschichle der Analomie im Millelaller, III . Arch, fiir Gesch. d. Medizin, vol. 7, 1914.

h K. Sudhoff, Abcrmals cine ncuc Handschrift der Anatomiachen Funfbilderserie, Arch, fiir Gesch. d. Medizin, vol. 3, 1910.

6 K. Sudhoff, Ein Bcitrag zur Gcachichte der Anatomic im Mitlelalter, Studien zur Gesch. d. Med., Heft. 4, 1908.

Fig. 19. Skeleton from a provengal manuscript in the University Library, Basel, Codex D II, 11 (End of thirteenth century). From Sudhoff, Studien, Heft. 4, pi. 1. 190S.

I in 20. Ske leton from Dresden Codex Xo. 310 (1323). 1mm SudhofT, Studien. Heft. 4. pi. 6. 1008.

What is probably on the whole a more accurate copy of this or another earlier original is a pen drawing in the Munich Ms. No. 13042, also of the fourteenth century (Sudhoff, ’07, ’08). The face is here indicated by three rhombs and an oblong, standing for the eyes, nose and mouth, the ribs are correctly represented as to number and attachment to the vertebrae, the scapula is indicated, as also the os innominatum, the only particular in which there is less accuracy than in the Provengal figure being the omission of the two bones of the forearm. But in addition to its greater accuracy this figure presents one peculiarity that is especially noteworthy, that is the absence of the crouching posture, so characteristic of the illustrations belonging to the FiveFigure Series. In this it forms a connecting link with the illustrations to be described as type III.

Before considering these, however, mention should be made of a fourteenth century osteological figure that can not readily be included in any of three groups. This is the single illustration of the Dresden Ms. No. 310, dated 1323 (fig. 20), which has been regarded by Sudhoff (1908) as an example of the Five-Figure Series, the other illustrations of the series being omitted. This is probably correct, since the posture of the figure is altogether characteristic and the accompanying Latin text is evidently the original, or a copy of the original, from which the osteological part of the Provengal text was translated. But the details of the illustration are quite different from both those of the Prufling series and those of the Persian series. The actual skeleton is figured and it is viewed from in front. The mouth with its batteries of teeth recalls that of the Ashmolean figure, but there the resemblance ceases; no details of the cranial bones are shown, but the coronal suture is represented. The vertebral column resembles that of the Provencal figure; there are twelve pairs of ribs, the upper nine of which are represented as curving around toward the ventral surface and the uppermost five pairs (according to the text there should be seven) are attached to the sides of a broad sternum. This is the earliest representation of the sternum, although it had been described centuries earlier, and it is noticeable that it is shown as a single bone although the text describes it as composed of seven bones. 7 The ossa innominata are shown, but they articulate with the upper lumbar vertebra and are quite distinct from the sacrum. The text gives a much fuller description of the parts of the skeleton than does that of the Priifling set and it would seem that the author had endeavored to give a representation of the parts described while adhering to the conventional five-figure posture.

The beginning of the fourteenth century witnessed the introduction of a new type of osteological illustrations, the earliest of which are, with good reason, supposed to be reproductions of figures which Gui de Chauliac informs us in his Chirurcjia were used by Henri de Mondeville in his lectures on anatomy at Montpellier. They occur in Ms. frangais No. 2030 of the Bibliothcique Nationale and have been reproduced by Sudhoff (1008). The manuscript or at least the anatomical portion of it is dated 1314, but if the figures are really miniature reproductions of the charts used by de Mondeville, their originals must date a decade earlier. There are altogether twelve figures, four of wdiich are especially interesting as showing attempts at portrayals of the skeleton. Unfortunately these, like the others, are too small to reveal many details and, furthermore, they have the appearance of being drawn from desiccated bodies rather than from skeletal preparations, except that the skull shows clearly the principal sutures. One of the figures is represented as seated, recalling somewhat the five-figure posture, but the other three are shown standing erect. One figure is seen from behind and shows the vertebral column and the scapulas, indications of the ribs occurring below the latter. In the front views the clavicles are shown and below them are two areas, indistinctly outlined, which seem to indicate areas where the pectoral muscles might in a dried cadaver conceal the underlying ribs. Below these areas ribs are sketchily showm, much as they w T ere in the Five-Figure Series. The abdomen is opened, but appears merely as a blackened area; the ossa innominata are not separate from the femora, and do not meet anteriorly; the patella is indicated in the seated figure, but not in the others; and the bones of the forearm, crus, man us and pes are not shown.

7 This is a tradition that comes down from Galen and was adopted by the Arabians, e.g. Avicenna.

Fig. 21. Skeleton from the De arte phimcrili of John Arderne (circa 1412). From Surlhoff, Studien, Heft 8, pi. 3, 1915.

Notwithstanding their imperfections, these figures seem to have served as types for a long series of representations which, gradually improving in detail, are to be found in manuscripts and, later in prints, through the fourteenth and fifteenth centuries. One of the earliest of these has been found, again by Sudhoff (1908), on the verso of the last page of a translation of the anatomy of Rhazes contained in Ms. No. 3599 of the Bibliotheque Mazarine (Institut de France). This looks much more like an actual skeleton, but, strange to say the skull show r s no sutures. A manubrium sterni and twelve pairs of ribs are represented, and again the abdomen is solid black. The innominates are clearly shown, but they fail to meet ventrally, allowing the sacral vertebrae to be seen; the two bones of the forearm are shown, but no patella. The posture is identical with that of the erect de Mondeville figures.

The Guido de Vigevano figures of circa 1345, reproduced by Wickersheimer from Ms. 569 of the library of the Chateau de Chantilly (see fig. 2), need merely mention. They show the Mondevillian posture, but being obviously drawn from cadavera exsiccata they show little osteological detail. The ribs and clavicles are crudely represented, the latter being shown perforated, 8 but beyond these there is nothing noteworthy. Of great interest is a figure in a manuscript epitome of John Arderne’s De arte phisicali et de cirurgia in the Royal Library of Stockholm (fig. 21). It dates probably to 1412 and has been reproduced by Sudhoff 9 and also by Sir D’Arcy Power in his translation of the manuscript. 10 It is distinctly reminiscent of the de Mondeville figures; indeed it suggests an attempt to combine in one figure both the ventral and the dorsal views of de Monde ville’s skeleton, for the vertebral column is shown throughout its entire length in the ventral midline, the clavicles and the ventral ends of the upper seven ribs articulating with it; below, it lies within the pelvis and gradually tapers to a series of coccygeal vertebrae, those of the sacrum being represented as quite separate from one another. The cranium shows the coronal and sagittal sutures, but they are decidedly askew, imparting thereby a decidedly rakish appearance to the figure. The clavicles are massive bones, but show no indications of a perforation; their massiveness suggests the idea that again they represent the clavicles plus the pectoral areas of the de Mondeville figures. The innominate bones are shown very crudely; they are rounded off above without any indication of the iliac portions and they fail to meet in a ventral symphysis. A single bone only is shown in the forearm and crus; the femur is very massive and shows no indication of either head or trochanter; the patella is distinct; and the carpus and tarsus are roughly indicated, the calcaneus, however, being plainly shown.

8 The text of the Dresden Codex, C 310, describes the clavicle thus: Furcula est unicum os perforatum per quod foramen ascendunt venae. The idea is no doubt borrowed from Avicenna.

9 K. Sudhoff, Weitere Beitrage zur Geschichte der Anatomie im Mittelalter, Arch, fur Gesch. der Med., vol. 8, 1915. q

10 Sir D’Arcy Power, De Arte Phisicali et de Cirurgia of Master John Arderne, Research Studies in Medical History No. 1, From the Wellcome Historical Medical Museum, 1922.

Another skeletal figure of this type occurs in an illustrated manuscript copy of certain works of Gui de Chauliac belonging to the City Reference Library, Bristol, England. It dates back to about 1430 and has been reproduced by Dr. Singer (1916). One of the illustrations represents a surgeon demonstrating a skeleton to a pupil. The skeleton is recumbent and clearly belongs to the type now being considered, resembling closely the Stockholm figure. It may be noted that it represents the clavicle distinct from the pectoral areas.

Again the type is shown in Ms. frangais No. 19,994 of the Bibliotheque Nationale in a skeleton drawn by one Etienne Beludet in 1454 and reproduced by Sudhoff (190S). The cranial sutures are shown and seven cervical vertebra; the upper thoracic vertebra are hidden by a broad area which is labeled ossa thoracis and bears the numbers 3, 4, 1, 5, 7. This area recalls the clavicles of the Stockholm figure, greatly exaggerated and, as has been suggested, probably represents the clavicle plus the pectoral areas of the de Mondeville figures. Below the areas are twelve ribs on each side, represented in the usual manner, and in the middle the vertebral column which bears the legend spondilia 12, some confusion having evidently taken possession of the artist’s mind as regards the number of vertebra. No sacrum is shown, but there are three coccygeal vertebra ( ossa caude). The innominates have the form of those of the Stockholm figure, no iliac portions being indicated, but each bone consists of two parts, osscie ( = ischium) and os pectus (= pubis), the latter uniting ventrally in a symphysis. In the forearm two bones are shown, and a label calls for four carpal bones ( ossa rachete ) though none is shown. On the femur the trochanter (vertebrum) is indicated by a legend; the patella ( occulus genu ) is represented; there are two bones in the crus; and a rude attempt is made to show four tarsal bones (ossa rachete) in addition to the calcaneus. Evidently the artist knew his Avicenna better than he did his skeleton.

An interesting figure, with curiously complex affinities, is that reproduced by Sudhoff (’08) from a manuscript in the Bibliotheque Nationale, Ms. lat. No. 7138. It probably dates from the earlier part of the fifteenth century and accompanies a text consisting of material partly from William of Saliceto and partly 'from Avicenna. The skull, slightly turned toward the right, recalls that of the Stockholm figure, although the sutures, including even the metopic, 11 are shown in greater detail; the thorax is practically identical with that drawn by Beludet (Ms. frang. 19,994), the enormous ossa thoracis bearing the numerals 1 to 7; each innominate consists of two parts, the os pectinis and the scia aut ancha, but instead of being rounded off above it is prolonged upward to meet the ribs, the iliac portion {ancha) being thus indicated; the arrangement of the ossa caude so as to form a triangle and the representation of the upper portion of the femur as a distinct bone ( vertebrum ) recall the osteological figures of the Persian FiveFigure Series; the hand and foot resemble those of Beludet’s figure, but the number of carpal bones is correctly given in a legend and the calcaneus is represented as a composite bone and is designated talus {tallis). Add to these complexities a trace of Salernitan influence in the statement in a legend of the total number of bones and bloodvessels in the body 12 and one obtains an idea of the interestingly composite character of this illustration.

The art of printing was invented in 1448, and it was not long thereafter before printed treatises of a medical character began to appear. At first these were of a popular nature, such as the Purgation Calendar published by Gutenberg in 1457 and the Bloodletting Calendar published in Mayence in 1462, and with them appeared loose leaves printed on one side with an illustration showing more or less of the anatomy of the human body, indications being given of the parts especially influenced by the various signs of the zodiac, forebears of the Farmer’s Almanacs, so widely distributed a generation ago. Somewhat more technical than these is a loose-leaf illustration, the Anathomia ossium corporis humani, printed at Nuremberg in 1493 13 and drawn by one Richard Helain who announces himself as a Parisian and a doctor artium et medicince. The figure (fig. 22) shows a skeleton in the erect position and lacks any astrological significance ; the various bones have pennon-like labels attached, recalling those of the Beludet skeleton but differing somewhat in the names they bear, a larger proportion of them being Arabic. The nomenclature, indeed, follows closely that of Avicenna.

The figure too differs much from that of earlier representations of the type, while still showing sufficient similarities to warrant its inclusion therein. The skull is quite similar to the other illustrations, but shows clearly the mandible as composed of two distinct bones, a belief dating back to Galen and stated in the text or legends of earlier illustrations, even if not portrayed. The ribs, correct in number, are still shown without any intercostal spaces, but a sternum is present. The region of the abdomen is deeply shaded and shows in the mid-line twelve ribless vertebrse, and between the innominates ventrally the sacrum is shown, without any particular relation to the rest of the vertebral column; a label gives the number of ossa caudce as three, and since the total number of the vertebrse is given as thirty, the implication is that the sacrum represents only three bones.

11 This is also shown in the figure from Ms. frangais 19,994.

12 This same influence is seen in the texts of the Dresden Codex, C 310, and the Provengal Ms.

13 The date printed on the illustration is 1293, but the figure 2 i3 evidently an error.

Fig. 22. Skeleton by Richard Helain (1493). From Sudhoff, Archiv, vol. 1, p. 57, 1907.

Fig. 23. Skeleton from British Museum Additional Ms. No. 2161s. From Sudhoff, Archiv, vol. £, p. 140, 191.5.

The clavicles are shown and the acromion processes, and there is an attempt to indicate the eight carpal bones ( ossa rascete). The treatment of the innominates is remarkable. There is a very feeble attempt to represent the concave form of the ilia and these and the ischia form a single bone, the os scie vel hanche, those of the two sides being curiously continuous across the mid-line in front of the vertebral column. More ventrally still is a bridge-like structure between the two bones, probably representing the pubis and termed in the attached label os pectinis vel femoris, halhafacar ( al harcafa ) and pyxis, all but the first being terms used by Avicenna, although he applies al harcafa to the ilium and pyxis denotes the acetabulum. The obturator foramen is distinctly represented. The patella is shown, and in the tarsus three of the bones receive special names, the talus (os cahab ), the calcaneus and the navicular, the remaining four being grouped together as ossa rascete.

Notwithstanding its many inaccuracies and imperfections this figure is unquestionably an advance upon those so far considered. It is not a copy of any of these, though manifestly influenced by them, but is drawn by one who had actually seen a skeleton and who knew his Avicenna and endeavored to harmonize experience and authority. Being printed it was accessible, and it was later copied with more or less modification for other publications, as for instance in the Kalendrier des Bergiers of 1495, where the astrological element again comes to the fore, and in the Buck der Wund-Artzeny of Hieronymus Brunschwig, published at Strassburg in 1497.

But anticipating Helain’s figure by nearly half a century and practically contemporary with Beludet’s drawing is an illustration in the Additional Ms. No. 21618 of the British Museum which has a note much more modern than any of the other pre-Vincian osteological illustrations. It dates back to 1452 and precedes a German translation of the Surgery of Bruno of Pavia, who, according to Gui de Chauliac, made summaries of Galen and Avicenna and of the operations of Albucasis. We are again indebted to Sudhoff for a reproduction of it (1915). The figure (fig. 23) is evidently drawn directly from the skeleton, conventionalism being almost discarded and an attempt made to represent the bones as they really are. The skull and the neck region are somewhat blurred, but the clavicles and scapula and the long bones of the limbs are for the first time represented with a fair amount of accuracy. The ribs, too, are much more true to Nature, the intercostal spaces being shown, and while the sternum and vertebra are greatly exaggerated in width, the sacrum is shown with something of its true form, and an attempt is made to indicate its curvature. The innominate bones are somewhat crudely drawn, but are more accurate in their relations than those of the Helain figure; indeed, it is only in the portrayal of the hands and feet that this drawing is surpassed by the later one.

Such were the osteological illustrations of the times preceding Leonardo, and it is with these that his must be compared in order that a just appreciaton of their merit may be had. Leonardo has left no drawings of the complete skeleton, but every part of the skeleton is figured and the figures demonstrate clearly his wonderful accuracy of observation and his quite as wonderful accuracy of delineation. They form a remarkable contrast to the works of his predecessors, the only figure which at all approaches his being that in the Additional Ms. 21618 of the British Museum, and even this falls far behind.

The nearest approach to complete skeletons are four drawings in the Uffizi Gallery of Florence, if they are really the work of Leonardo as Holl and Sudhoff (1914) believe them to be. Two inscriptions, one on the recto and the other on the verso, claim them as Leonardo’s and in execution the drawings bear out the claim. The inscriptions, however, are not in Leonardo’s handwriting, nor do the labels attached to one of the figures and reading from left to right appear to be. The shading, too, seen in one of the figures is right-handed. These discrepancies, if so they may be termed, are, however, of less significance than the evidence from the drawings themselves. They are on a single, soiled and mended folio, two on the recto and two on the verso, and represent the greater part of the skeleton from in front and from the left side, from behind and from the right side; the skull and the left arm are omitted in all of them and the feet are indistinct. But whether or not these drawings are accepted as Leonardo’s, there are others in Anat. A (AnA, 8v and 13) which show his conception of the parts of the axial skeleton (fig. 24), even though none are so inclusive as the Uffizi drawings; they reveal an accuracy of delineation hitherto unknown and, what is more important, accurate observation almost free from influence of dogma.

The number of vertebra was generally accepted by the mediaeval anatomists as thirty, this being the number given by Avicenna, before him by Galen and after him by Mondino. They also recognized seven of these as cervical, twelve as thoracic with a corresponding number of rib pairs and five as lumbar; the sacrum, however, was supposed to represent only three vertebra and the coccyx another group of three. Leonardo, however, boldly discarding tradition, figures and describes the total number as thirty-one, recognizing that the sacrum represents not three but five vertebra (AnA, 8v) and reducing the number of the coccygeal to two. The great variability of the latter sufficiently explains the number assigned to them; much more important is the fact that Leonardo was the first to perceive the correct number of vertebra in the sacrum and to represent it accurately.

Fig. 24. The vertebral column by Leonardo. (AnA, 8v.)

Fig. 25. The cervical vertebra?. (AnA, Sv.)

Fig. 26. Skull cut to show frontal an-1 maxillary sinuses. (AnB, 41v.)

But still more important is the fact that he was the first to represent correctly the curves of the spinal column, the tilting of the sacrum whereby the weight of the trunk is brought directly over the lower limbs, and the tilting and curvature of the ribs so essential for the correct understanding of the mechanics of respiration. In short he was the first to perceive the static and dynamic conditions demanded of the skeleton by the erect posture, and not only so, but he anticipated by several centuries the final recognition of the correct position of the pelvis by Naegele and the brothers E. F. and W. C. Weber. 14 Not even Vesalius, who effected a revolution in the science of anatomy and indirectly in the science of medicine, approaches Leonardo in the accuracy in this respect of his representations of the skeleton. As Holl (1914) has said, in speaking of Leonardo’s drawings of the skeleton —

“They have life, if such an expression may be used, while Vesalius simply assembled the bones of a man without respect to the natural conditions in the living body; Vesalius’ skeletons if they came alive could neither walk, nor stand, nor breathe.”

Leonardo, however, was not infallible, as a glance at figure 23 will show. A spinous process, without a corresponding vertebral body, is interposed between the spines of the second and third thoracic vertebra. He also represents (AnA, 13) eight true ribs, instead of the usual seven, but eight occasionally occur, and he shows the sternum as composed of six sternebra together with the xiphoid process ( pomo granato), an incomplete surrender to tradition which required as many parts to the sternum as there were attached costal cartilages (Avicenna). 15

It is a little surprising that Leonardo with his predilections for mechanical studies did not give special attention to the first two cervical vertebra. They are, it is true, figured separately (AnA, 8v) (fig. 25) , together with the third vertebra, and the drawings are very accurate, all the important parts being shown and designated by letters; but the text gives no interpretation of the lettering, it merely states that these two vertebrae differ from the rest. Elsewhere Leonardo speaks of the various movements of the head (AnA, 4 and AnB, 32) and evidently appreciated the occurrence of lateral inclination of the head at the occipito-atlantoid articulation, but he does not refer to the location of the rotatory movements, although one would have imagined that with his knowledge of the conformation of the axis and of its relation to the atlas this would have appealed to him.

14 See C. Langer (1867).

15 It may be noted that the Uffizi drawings also show eight pairs of true ribs, but the sternum is undivided and has no xiphoid process.

Throughout the mediaeval period the description of the bones of the skull had not progressed beyond the stage in which it was left by Galen; indeed, confusion and uncertainty had already appeared with Avicenna and the confusion became worse confounded in later treatises, based on Avicenna without personal observation. Leonardo made no attempt to lessen the confusion; he has left no description or even enumeration of the constituent bones, and yet he undoubtedly possessed a better understanding of the skull and its relations than did his immediate predecessors. He has left two important drawings of the skull which reveal the thoroughness with which he carried out his anatomical investigations. Not content with a mere surface view or with the removal of the calvarium, he shows (AnB, 40) a medial sagittal section of the skull in which the three cranial fossae are clearly delineated and also the frontal and sphenoidal sinuses. His penchant for proportion is manifest, the entire skull, including the mandible, being enclosed within a quadrangular area, bisected by a horizontal line which in modern parlance might be termed the glabella-lambda line. The lower half of the area is again bisected by a line that passes through the anterior margin of the foramen magnum and two vertical lines are shown, one passing through the posterior part of the body of the sphenoid and the other through the anterior margin of the foramen magnum. Where the anterior vertical line crosses the glabella-lambda horizontal, Leonardo locates the sensorium commune. It is to be noted that as a rule Leonardo represents the skull in its natural position, in some cases showing it blocked up behind so that the glabellalambda line is truly horizontal.

His representation of the frontal and sphenoidal sinuses has already been mentioned; the frontal sinuses are again shown in another figure (AnB, 41v) and in this the maxillary antrum is also well shown (fig. 26). He describes the latter (AnB, 40) as having a capacity equal to that of the orbit which lies above it, and regards it as containing a humor which nourishes the roots of the teeth. It receives veins which descend from the brain, passing through the cribriform plate of the ethmoid (colatorium ) , which discharges into the nose the superfluity of the humors of the head. He shows, too, the bony naso-lacrimal duct, “through which the tears ascend from the heart to the eye, passing by way of the nasal canal.” Here again is a curious example of the influence of antique tradition.

It seems that the credit for the first representation of the cranial sinuses, except the mastoid, belongs to Leonardo. They were unknown to Galen and therefore to Avicenna. Vesalius mentions them, but the maxillary sinus had to wait until 1651 for its full description by Highmore, who called it the Antrum, a term previously used for it by Laurentius. The mastoid sinus was observed by Ingrassias (1603). 16

Bonos of arm in supination and pronation, together with scapula and biceps muscle. (AnA, lv.)

The skeleton of the limbs was especially attractive to Leonardo, and illustrations of the bones of both the upper and lower limbs are quite numerous, all showing a degree of accuracy in their delineation that stands in marked contrast to what one finds in earlier representations, such as that of Helain (fig. 21). In the upper limb he found special interest in the mechanism of pronation and supination, many of the drawings, such as those of An A, lv, showing both the bones and the relations to these of the more important muscles; he is evidently carrying out the plan which he lays down for his illustrations, to represent the bones “so that one may understand their true form, and afterward to cover them gradually with their nerves, veins and muscles” (AnA, lv). He figures the bones of the limb in pronation from before, from behind and from the side (AnA, 5) (fig. 27) and with great exactness, the upper ends of the radius and ulna (AnA, lv), correctly demonstrating the behavior of the radius in this movement as a rotation about its own axis above and about the lower end of the ulna below. Leonardo’s thoroughness in observation is exemplified by the fact that he recognized the restricting effect on the rotation of flexion of the forearm, stating that in flexion the lower end of the radius revolves through half of a complete revolution, while in extension it makes three-quarters of a revolution (QIV, 14). His statement and figures concerning this movement of rotation are a decided advance on the bald statement of Avicenna that in rotation the radius is twisted as if it came from the inner part and gradually twisted to the outer part, evidently referring to its movement in supination. 17

Of the scapula ( spatola ) and clavicle ( forcula ), Leonardo gives excellent representations in AnA, 13, but in one figure the right clavicle seems to be turned end for end, and the acromion is shown as a separate bone. Roth (1907) criticizes him for representing the coracoid and acromion processes as distinct bones. In the case of the coracoid one may doubt whether Leonardo intended it to be regarded as separate from the scapula ; in some drawings, such as AnA,lv (fig. 16), a line clearly separates it from the upper border of the scapula, but in others, such as AnA, lv (fig. 18), and AnA, 2 (fig. 25), it is evidently a process of the scapula, and so he speaks of it in the text on AnA,

18 For an account of the early history of the discovery of the maxillary sinus see W. Tacke (1923).

17 Leonardo makes the curious statement (AnA, lv) that the arm is shorter in pronation than in supination and gives a rough diagram to show why this should be so. If one were dealing with rigid bodies and there were no opposing factors his method might be correct, but he apparently overlooks the fact that the plane of the circle, of whose circumference the lower end of the radius describes an arc, is so nearly in the transverse plane of the arm that the displacement would be negligible.

14v, terming it the punla or rostro della spatola. It may be recalled, however, that the coracoid ossifies from a special center and does not unite with the rest of the scapula until the fifteenth year or even later, and Leonardo may therefore have seen it as an apparently distinct bone.

The acromion is certainly figured as a distinct bone in several drawings, such as AnA 12, fig. 176; 13, fig. 195; 14v, figs. 213, 216 and 218. Here again one has to do with an independent ossification, the acromion remaining cartilaginous until about the fifteenth year, when a center of ossification appears in it, followed by a second about two years later; the two centers soon unite and the bone fuses with the rest of the scapula somewhere about the twenty-first year, though occasionally the union fails to occur. It is quite possible that Leonardo may have been representing what he observed in a young individual, and this possibility is emphasized by the fact that in one passage (AnA, 14v) he speaks of the structure as a cartilage, and in a figure of the scapula of an aged man (AnB, 32) the acromion is shown continuous with the spine. Less probable is the suggestion that in this case Leonardo may have been dominated by ancient tradition, Galen, in the de ossibas, stating, but not confirming, the opinion of some writers that in man alone the acromion is a distinct bone, the os acromiale. But neither Avicenna nor Mondino, by whom Leonardo would be most likely to be influenced, speak of the acromion as other than a process of the scapula. If Leonardo is to be criticized on the ground of inaccuracy a much better case might be made out from the figure on QII, 5v (fig. 33) in which the scapula is shown without any indication of an acromion process. The sternum too is represented as composed of eight sternebrse and, strange to say, the first pair of ribs is attached to the eleventh vertebra ! T rue, the figure is evidently diagrammatic and drawn to show the supposed actions of muscles rather than osteological details, but still the inaccuracies are glaring. The figure could not have been drawn from a dissection, but seems rather a product of memory, which failed to visualize the parts correctly. Leonardo stands at a disadvantage in that the folios, his journal intime, frequently give us his fugitive ideas, premature notions destined to be modified by further observation and reflexion, or even to be discarded.

The figures of the humerus, radius and ulna ( focile major ) are, as a rule, wonderfully true, as compared with the attempts of his predecessors. He nods, however, in one figure (AnA, 5, fig. 78) where he gives the lower end of the ulna the form of that of the radius. He makes a memorandum to inquire into the purpose of the prominences of the bones of the arm (AnA, 5), but mentions only that of the deltoid tubercle of the humerus, incorrectly assuming it to be the origin of the brachialis muscle. But it is in the figures of the hand that his advance over earlier representations is most marked (fig. 28). He figures the carpal bones ( rasetta ) for the first time with some approach to accuracy (An A, 10, lOv), designating them by letters of the alphabet; in the text (AnA, lOv) he terms the trapezium os basilare and points out that both the first bone of the thumb and that of the index articulate with it. He follows earlier authors in recognizing only four bones in the metacarpus (pettine = pecteri) , what the text-books of today usually term the first metacarpal being regarded more correctly as a phalanx, each digit thus having three phalanges. He makes no mention of sesamoid bones in the hand.

Fig. 28. Bones of hand, with dissection of tendons and ligaments of fingers. (AnA, lOv.)

Fig. 29. Various figures of bones of foot with sketch of bones of shoulder. (AnA, 12.)

He figures the innominate bones with remarkable accuracy, giving them, as has been stated, their correct inclination, but of the parts of which they are composed he names only the ileum (mica). 18

The femur (osso del coscia), tibia, fibula and patella ( rotula or burella ) are represented from various viewpoints and in both extension and flexion (AnA, 9 and 13), and again the accuracy of their representation as compared with earlier figures is most striking. Once again, however, his attention wanders, when in a figure on AnA, 3v, he reverses the positions of the tibia and fibula. The significance of the prominences on the bones interests him here, as well as in the upper limb, and he has a note of inquiry (AnA, 5) as to the significance of the lesser trochanters of the femora, using for them the term spondyli, a term recalling vertebrum which is applied to the great trochanter in mediaeval manuscripts.

Of the foot he gives a number of illustrations from various aspects (AnA, 3v and 12), the bones for the first time being shown in their true proportions (fig. 29), although there is a decided failure to show the arch of the foot. On AnA, 3v, Leonardo states that the bones of the foot are twenty-seven in number; Avicenna, following Galen, mentions twenty-six. One finds here an example of Leonardo’s independence of tradition and reliance upon his own observations — -a truly modern attitude. He obtains the number twenty-seven by including the two sesamoid bones beneath the metatarso-phalangeal joint of the great toe. If these be deducted, Leonardo’s number becomes twenty-five, one less than that of Avicenna, and it is here that Leonardo’s accuracy and independence of authority is shown; for he evidently counts, as he has figured, only two phalanges to the little toe (fig. 29), while Avicenna recognizes three. Three is, of course, the typical number, but the apparent reduction to two, as a result of the fusion of the terminal and middle phalanges, is so frequent that one may feel sure that Leonardo had before him such a condition and drew it as he saw it.

He does not name the bones of the tarsus except in the case of the cuboid, which he calls os basillare and notes that the use of each of the prominences on its plantar surface should be described, also “each of its perforations and into how many parts it is divided” (AnA, 3v). The sesamoid bones were known to the older authors, Avicenna, for example, mentioning them and noting their relation to the joint. Leonardo, who terms them ossi glandulosi or ossi petrosi, has added materially to the appreciation of their true significance, since he defines them as being always situated toward the ends of tendons, where these are attached to the bone (AnA, 12). Furthermore he recognizes as belonging to this category of bones, not only the four associated with the great toes, but also “two in the tendons termed omeri del collo, where these join with the upper heads of the bone termed aiutorio (i. e. the humerus) and two others in the ends of the muscles which arise in the alchatin and end in the knee.” The omeri del collo undoubtedly are the acromial portions of the trapezius muscle and the sesamoid bones in their tendons may be identified with the ununited acromial processes. The sesamoids at the knee joint would seem to be the patellae, for in a note on AnB, 18v, which shows the muscles of the thigh from in front and from the inner side, it is stated that all the muscles of the thigh reach the knee and are converted first into a nerve (?'. e. tendon) and underneath this into a delicate cartilage. It is evident that here Leonardo is speaking only of the rectus femoris and vasti muscles, but in the passage quoted above he errs in assigning the origins of all three to the alchatin, 19 meaning by that term the innominate bone, even though his figures indicate that the vasti arise from the femur. However, in spite of these slips in memoranda intended for his own guidance, he long anticipated one of the conclusions of modern anatomy in assigning the patella to its proper status as a sesamoid bone.

18 He applies the term ascia (ischion) to the great trochanter on AnA, 15v.

Naturally Leonardo can have nothing to say as to the minute structure of bone, but he was interested in the internal structure of the various bones and made memoranda to the effect that each one is to be sawn through to show its structure (AnA, lv and 18; QI, 2), a plan that, apparently, was never carried out. However, he notes (QI, 27) that some are hollow, some contain marrow, some are spongy, some are thick and some are thin and, indeed, that one bone may show all these characteristics at different parts. He describes bone as being of inflexible hardness and destitute of sensation (QII, 18v); its interior is composed of spongy substance, blood and soft fat, and the spongy substance is composed of bone, fat and blood. Cartilage, which invests the extremities of bones is a hard substance like indurated tendon or softened bone, being pliable, unbreakable and acting like a spring. It always intervenes between bone and tendon, because it partakes of the nature of both substances (QII, 18).

19 There is some confusion in the use of the term alchatin. Leonardo uses it or the word catino to denote the innominate bone, but in Avicenna it is applied to the lumbar vertebrae.

Nor can Leonardo be said to have added anything to the knowledge of the joints, except in that he has more accurately represented the form of their constituent surfaces. In considering the knee he speaks of its articular capsule, but describes it as composed of as many layers as there are muscles descending to the knee, and on this supposed fact he bases a generalization (AnA, 15; AnB, 18) which gives to the capsules of all joints a similar layered structure. On AnA, 15 he correctly notes the important role played by the muscle tendons in maintaining the bones in contact at the joints.

He notes the existence of ligaments extending from bone to bone, but gives them little attention. He represents (AnA, 7v) oblique ligaments extending between adjacent metatarsals and basal phalanges crossing to form a letter x, but these must be regarded as artefacts, perhaps produced by imperfect dissection of the plantar ligaments of the joints. In a curious passage (AnB, 28) he points out that in the joints of the feet and hands a convexity is received into a concavity and explains this fact on the ground that Nature did not desire to make the feet too large which they w r ould have been if convexity articulated with convexity, unless the extra size was compensated for by the digits being all of the same length or else by some having two joints and others one. The significance of these last statements is not clear, but the passage is interesting in revealing Leonardo’s belief in the adamantine inalterability of bone ; the idea of its plasticity was slow to develop.

One other statement concerning the joints may be mentioned. He notes (Ash 2 , 28v; see also TP, 261) that in children the position of the joints is indicated by constrictions, whereas in adults the joints are prominent, and explains this by the flesh covering the bones losing its ‘'‘superfluity of fullness” as age advances, the skin thereby coming near to the bones; but at the joints there is no flesh, but only cartilage and tendons, and so there is nothing to grow leaner.

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Pages where the terms "Historic" (textbooks, papers, people, recommendations) appear on this site, and sections within pages where this disclaimer appears, indicate that the content and scientific understanding are specific to the time of publication. This means that while some scientific descriptions are still accurate, the terminology and interpretation of the developmental mechanisms reflect the understanding at the time of original publication and those of the preceding periods, these terms, interpretations and recommendations may not reflect our current scientific understanding.     (More? Embryology History | Historic Embryology Papers)
   Leonardo da Vinci (1930): 1 Introductory | 2 Anatomy from Galen to Leonardo | 3 Possible Literary Sources of Leonardo’s Anatomical Knowledge | 4 Anatomical Illustration before Leonardo | 5 Fortunes and Friends | 6 Leonardo’s Manuscripts, their Reproduction and his Projected Book | 7 Leonardo’s Anatomical Methods | 8 General Anatomy and Physiology | 9 Leonardo’s Canon of Proportions | 10 The Skeleton | 11 The Muscles | 12 The Heart | 13 The Blood-vessels | 14 The Organs of Digestion | 15 The Organs of Respiration | 16 The Excretory and Reproductive Organs | 17 The Nervous System | 18 The Sense Organs | 19 Embryology | 20 Comparative Anatomy | 21 Botany | 22 Conclusion | References | Glossary of Terms | List of Illustrations

Reference: McMurrich JP. Leonardo da Vinci - the anatomist. (1930) Carnegie institution of Washington, Williams & Wilkins Company, Baltimore.

Cite this page: Hill, M.A. (2021, May 17) Embryology Leonardo da Vinci - the anatomist (1930) 10. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Leonardo_da_Vinci_-_the_anatomist_(1930)_10

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