A folio from Leonardo's 'Anatomical Manuscript B'.

Recto: a drawing of the lungs in the thorax, with extensive notes on respiration.

Verso: two drawings of the nervous system, with a small sketched figure to illustrate the precept that the nervous system should be represented within the outline of the body.

These drawings of the brain, spinal cord and spinal nerves, and a pair of cranial nerves are suggestive rather than detailed, but Leonardo has nonetheless managed to convey the complexity of the brachial plexus and the lumbosacral plexus . At the lower end of the spinal cord he has indicated the filum terminale, a delicate fibrous strand that extends beyond the conus medullaris as far as the coccyx. Leonardo stated between the drawings ‘Tree of all the nerves: and it is shown how they all have their origin from the spinal cord, and the spinal cord from the brain’; nonetheless both main drawings also show what are presumably the left and right vagus nerves descending directly from the base of the brain.

The drawings go some way to fulfilling a memorandum on 919040v, to ‘draw a man with arms open and with all his nerves and their uses. You should employ the most detailed diligence, especially for the reversive [recurrent laryngeal] nerves in all their ramifications’. Similarly, the sketch of the body at lower centre is annotated, ‘In every demonstration of the whole extent of the nerves, draw the external outlines of the body which denote the shape of the body.’ This sort of memorandum, in which Leonardo reminds himself about further illustrations, was to become one of the main themes of his anatomical notes in later years.

The image bears a remarkable resemblance to John Evelyn’s anatomical table of the nerves, now in the Hunterian Museum of the Royal College of Surgeons, London. The table is one of a set of four prepared by Giovanni Leoni d’Este, dissector to Johann Vesling, professor of anatomy at the University of Padua, and consists of the spinal cord and nerves of the trunk and limbs, dissected out, glued to a wooden panel and varnished. Evelyn attended Vesling’s lectures in Padua and purchased the tables from Leoni in 1646; they appear to be the earliest surviving anatomical preparations in Europe, and hint at the sort of didactic material that the new wave of investigative anatomists – with Leonardo, Marcantonio della Torre and later Andreas Vesalius in the vanguard – might have prepared.

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