Leonardo da Vinci's Animal Anatomy: Bear and Horse Drawings Revisited

Leonardo da Vinci was one of the most influencing personalities of his time, the perfect representation of the ideal Renaissance man, an expert painter, engineer and anatomist. Regarding Leonardo's anatomical drawings, apart from human anatomy, he also depicted some animal species. This comparative study focused only on two species: Bears and horses. He produced some anatomical drawings to illustrate the dissection of "a bear's foot" (Royal Collection Trust), previously described as "the left leg and foot of a bear", but considering some anatomical details, we concluded that they depict the bear's right pelvic limb. This misconception was due to the assumption that the bear's digit I (1st toe) was the largest one, as in humans. We also analyzed a rough sketch (not previously reported), on the same page, and we concluded that it depicts the left antebrachium (forearm) and manus (hand) of a dog/wolf. Regarding Leonardo's drawing representing the horse anatomy "The viscera of a horse", the blood vessel arrangement and other anatomical structures are not consistent with the structure of the horse, but are more in accordance with the anatomy of a dog. In addition, other drawings comparing the anatomy of human leg muscles to that of horse pelvic limbs were also discussed in motion.