LEONARDO DA VINCI

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SKETCHES AND DRAWINGS

NERVES AND VESSELS

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Publisher's device: A central lantern with a lit candle, from which eight arms radiate outward, each ending in a hand holding a smaller lit lamp.

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original: "nerfs, vaisseaux"

On the Movement of the Human Body

The soul, which governs the body, does not act without the instruments of the nerves and muscles Leonardo often viewed the body as a complex machine where the soul acted as the primary mover. Just as the weight of a clock is the cause of its movement, so the contraction of the muscles provides the force that moves the bones at their joints.

Of the Arm and its Leverage

The muscle which is located at the front of the arm The biceps brachii serves to pull the lower arm toward the shoulder. Observe how, when the arm is bent, this muscle increases in thickness while it decreases in length.

The center of gravity changes with every movement of the limbs.

When a man carries a heavy burden upon his back, he must lean forward in proportion to the weight he carries, so that the center of gravity falls directly over the soles of his feet. If he did not do this, the weight would pull him backward and he would fall. This is a law of nature that applies to all living things.

Note: The tension of the tendons is like the cords of a cross-bow.

The pulleys Leonardo uses the term 'taglia' or 'carrucola' to describe the mechanical function of joints and tendons of the body are so arr...