Myology
Most of the drawings are
based fundamentally upon the dissection of
the centenarian. Leonardo's early dependence
upon spare living subjects led him to the
conception that muscles such as the deltoid,
pectoralis major, etc., are compound or multiple
muscles, and this explains his division of
these muscles in dissection into multiple
fasciculi. Logically he extends these ideas
to the production of cord diagrams. While
it is true that the presentation of muscles,
as in the case of the series on the upper
extremity, viewed from every aspect, is indicative
of his very considerable imaginative skill,
yet in the representation of the abdominal
muscles Leonardo is still relying upon tradition.
As mentioned above, almost all the studies of muscles are from the period 1505-10,
and it was during this period that he had come into possession of Galen's De
usu partium. It is suspected that Leonardo derived much profit from this
work, especially regarding his consideration to antagonistic muscle function,
and it may have been the cause of his very considerable preoccupation with the
problems of respiration and the action of the intercostal muscles. It is extremely
difficult to attempt any comparison between the treatment of muscles by Leonardo
and contemporary physicians since myology was at the time one of the most poorly
understood aspects of anatomy. Among the difficulties plaguing any study of the
muscle structure was the lack of any proper myological nomenclature. Few of the
muscles were specifically named, and the result was constant confusion of identity
which bothered Leonardo no less than the medical fraternity...
Myology
of the trunk
Surface modeling of the muscles of the back end upper arm. Leonardo's figures
illustrating the surface modeling produced by the underlying muscles were doubtless
intended for the instruction of artists. One would judge that they were not drawn
entirely from the living model since they reflect features derived from his method
of dissection. Thus we observe the deltoid muscle divided into several distinct
elements indicating the artificial divisions which he made with the knife. These
exaggerations are frequent in studies of this type. However, Leonardo was aware
of the differences in surface contours produced by accumulations of fat and intended
to illustrate these differences as indicated in the note below.
"The most prominent
parts of thin individuals are most prominent
in the muscular and likewise in the fat. But
the difference which exists in the shape
of the muscles of the fat as contrasted with
the muscular will be described below". The remaining notes are memoranda outlining
future procedures.
"You will
make the rule and the measurement of each
muscle and give the reason of all their
uses, in what manner they work and what moves
them, etc. First make the spine of the back;
then clothe it step by step with each of
these muscles, one upon the other, and put
in the nerves, arteries and veins to each
individual muscle; and in addition to this,
note to how many vertebrae they are Attached,
and which intestines are opposite to them
and which bones and other organic instruments,
etc". The phrase "organic instruments" is
Galenical and had special meaning to mediaeval
anatomists, corresponding approximately
to present concepts of functional systems.
Thus the eye was regarded not only as an
organ but when taken together with all
structures pertaining to it, constituted
the instrument of sight.
1983 Dover Republication of Leonardo on the Human Body
: The Anatomical,
Physiological, and Embryological Drawings of Leonardo da Vinci. ISBN: 0-486-24483-0
