Make the rule and give the measurement of each muscle, and give the
reasons of all their functions, and in which way they work and what
makes them work &c.

[4] First draw the spine of the back; then clothe it by degrees, one
after the other, with each of its muscles and put in the nerves and
arteries and veins to each muscle by itself; and besides these note
the vertebrae to which they are attached; which of the intestines
come in contact with them; and which bones and other organs &c.

The most prominent parts of lean people are most prominent in the
muscular, and equally so in fat persons. But concerning the
difference in the forms of the muscles in fat persons as compared
with muscular persons, it shall be described below.

[Footnote: The two drawings given on Pl. CVIII no. 1 come between
lines 3 and 4. A good and very early copy of this drawing without
the written text exists in the collection of drawings belonging to
Christ's College Oxford, where it is attributed to Leonardo.]