An anatomical study of the principal organs and the arterial system of a female torso, pricked for transfer. 

This magnificent drawing is the culmination of Leonardo’s researches into the viscera contained in his 'Anatomical Manuscript B' (919018-59, 919095): it contains many features transcribed from the studies in that notebook, though elements of the gastrointestinal tract and nervous system are not present.

The sheet was compiled in several stages. The outlines of the torso from the armpits downwards and the diaphragm were first sketched in red and then black chalk; the sheet was then folded in half and these outlines were pricked through the two thicknesses of paper to give a perfectly symmetrical framework for the addition of the internal features.

The trachea and bronchi were copied from the left-hand drawing on 919054v. In front of the bifurcation of the trachea are the upper ends of the great vessels, as on 919028r: the aortic arch is bovine, with both right and left brachiocephalic arteries, and the brachiocephalic veins are similarly symmetrical; the venous return from the right lung is to the superior vena cava rather than to the left atrium of the heart; and the arch of the azygos vein correctly connects with the superior vena cava. The heart consists only of the ventricles, with no atria. The lower aortic bifurcation and vena cava formation are shown correctly at the level of the umbilicus, though the subsequent vessels extend too far laterally in the thigh/gluteal region, as in 919026r. The ascending lumbar veins can be discerned on either side of the inferior vena cava and thoracic aorta, as in 919026.

The liver, spleen (drawn twice) and kidneys are in approximately the correct locations, as in 919028v though this is such a heavily worked part of the sheet that the blood vessels are hard to follow. Passing diagonally from the umbilicus to the liver is the umbilical vein, and looping downwards from the umbilicus are two pairs of vessels, the umbilical arteries and their imaginary venous companions, as in cats. 919039v and 919021r. At first glance these seem to be continuous with the ureters and ovarian vessels, but closer inspection reveals that they connect to the common iliac vessels. The ureters pass from the kidneys to the bladder, drawn as a circular outline over the vagina, with no urethra visible and a papilliform urethral orifice (as in 919095r), in an uncertain relationship to the sectioned vagina. The right ovarian vein and artery travel from the suspensatory ligament of the ovary to the vena cava and aorta, and the left ovarian vein is correctly shown terminating at the left renal vein; but the left ovarian artery is similarly shown originating at the left renal artery, whereas it should also spring from the aorta.

The perfectly spherical (and rather large) uterus is ‘scalloped’ within, forming the traditional seven chambers, and its greatly exaggerated ligaments extend like horns to the flanks of the pelvis. Vessels can be traced meandering upwards from the upper surface of the uterus, alongside the ascending lumbar veins; these are possibly the vessels thought to carry the retained menses of pregnancy to the breasts, first seen in 919097. Though the nipples are correctly positioned, the breasts themselves appear oddly masculine.

Having added all this detail, Leonardo attempted to clarify the spatial relationships of the organs and vessels by shading with pen hatching and yellow wash. The outlines of the torso and the diaphragm were adjusted and inked in; it was then that the inky-fingered Leonardo picked up the sheet, for his thumbprint is plainly visible at the left edge of the sheet, smudging the wet outline a little just above the central fold, with a corresponding partial fingerprint on the verso of the sheet.

Leonardo then folded the sheet down the central axis again, and pricked all the supposedly symmetrical elements through both sides of the sheet. Finally, the sheet was unfolded and the non-symmetrical elements, such as the liver and heart, pricked through. The resulting dense array of prick-holes can be seen on the verso of the sheet. Leonardo could then use this sheet as a template, pouncing chalk dust through the holes to make a pattern of dots to be joined with pen and ink, thus creating an unlimited number of ‘clean copies’ for further elaboration. RCIN 919071 includes the note ‘make a pounce of the rings [of the trachea] and then add the veins and arteries and substance of the lungs’, which may well refer to an elaborated replica of the upper part of the present sheet. On 912280v is an extensive partial replica of the image, with several organs not inked in, but the arrangement of the vessels in the abdomen much clearer than here.

Despite the complexity of the present image, it is still plainly a working study, with the marginal notes only loosely relevant. And at the top of the sheet is a memorandum to make equivalent studies from the side and from behind: "Draw this demonstration seen also from the side in order that knowledge may be given as to how much one part is behind another; and then draw one from behind in order that knowledge of the vessels located near the spine and heart and great blood vessels may be given."

Text from M. Clayton and R. Philo, Leonardo da Vinci: Anatomist, London 2012