Recto: The skeleton. Verso: The muscles of the face and arm, and the nerves and veins of the hand

Recto: two studies of the thorax, showing the spinal column and upper arm; the bones of a figure from the neck to the pelvis; the skeleton of the pelvis and the legs; the bones of a right leg; notes on the drawings. Verso: two studies of a head in profile to the right, showing facial muscles; a right arm and shoulder in profle to the right; a study of a right arm and hand seen from in front; two studies of a right hand, with the palm towards the spectator, showing arteries and nerves; the head of a man with curly hair, in profile to the right. This is Leonardo’s most complete representation of a skeleton, seen from front, side and back, in the manner of an architectural drawing. The studies at lower right show the line of action of the quadriceps muscle through the kneecap. There are some minor errors of detail, such as the exaggerated length of the shoulder blade against the ribcage, but Leonardo’s understanding of structure was unprecedented. (RCIN 919012r) This sheet is among a series compiled by Leonardo probably in the winter of 1510-11, in collaboration with Marcantonio della Torre, the professor of anatomy at the medical school of Pavia. This was the period of Leonardo's greatest achievements as an artist-anatomist, and his lucid drawings of the bones and muscles have rarely been bettered. Leonardo's interest was in the mechanical structure of the body, the first time that the study of anatomy had ever been conceived in this way, and any reference to proportion was entirely incidental. Text adapted from Leonardo da Vinci: A life in drawing, London, 2018