(folio 19 verso) Then you will see in the midst of the lung the heart,
covered by its membranes. [It is thus situated] that the air attracted
by this lung should cool it, and that thus the heat and spirit of
the heart be tempered. This member is the most important of the four
[principal members], because it is the first to live and the last to
die. It is of medium size compared with the other members of man, but
compared with the hearts of other animals it is very large, because
man, in a quantitative and not an intensive sense, has more natural
heat than other animals. It is pyramidal, that is in the form of a
flame; because it is of excellent warmth, therefore it is necessary
that it should be of a shape resembling a flame. Its figure is also
called ‘pine-shaped’, because it is wide below and narrow above, being
thus formed that distinction could better be made between its cavities
or ventricles; moreover, had it been made of a shape all uniform as is
the lower part, it would be too heavy and ponderous.
This member is situated in the middle of the entire body, measured in
every direction; that is, in the middle between the upper and lower
parts: in the middle also between front and back and right and left,
like a king standing in the midst of his kingdom, and this was done
that it might give the strength of life equally to all the members; and
although the heart as regards its foundation and base be in the middle,
yet its point declines to the left below the left breast, so that it
warms the left side as the liver warms the right.
This member is sustained and strengthened by a certain cartilaginous
bone. For since it is continually moving, it needs some point of
purchase to support it in its movements. Moreover, it has a certain
fatty layer on the outside which prevents the heart from drying and
keeps it moist: and there are certain veins and arteries dispersed
through its substance: and it is formed also of a kind of hard flesh so
that it may sustain many and forceful movements; also it is formed of
longitudinal, latitudinal, and transverse fibres, so that it may have
the power to attract, retain, and expel.
This member has three ventricles or chambers, like the brain. One
ventricle is on the right side, the second on the left, and the third
in between. The right ventricle towards the liver has two orifices. One
is towards the liver and is very large. Into this there enters a vein
called _vena chilis_, which arises in the convexity of the liver and
brings the blood from the liver to the heart. In that right ventricle
the blood is purified, and then sent by the heart to all the other
members.
Now since the heart attracts by this orifice of the _vena chilis_
more than it expels, therefore nature ordains that in the moment of
contraction when the blood is expelled this orifice closes, and when
the heart dilates it opens.
Moreover there are three little valves (_hostiolitti_) or doors opening
from without inward, and these valves are not very depressed; so that
by this same orifice only part of the purified blood is expelled to
the other members, because part goes to the lungs and the remainder
forms the vital spirit; therefore nature ordains that these valves do
not entirely close. From the _vena chilis_, before it enters the cavity
of the heart, there arises another vein, which surrounds the root of
the heart; and from it are given off branches which disperse themselves
through the substance of the heart, and from the blood of that vein the
heart nourishes itself.
The right ventricle towards the lung has another orifice into which
opens the _arterial vein_, bringing the blood from the heart to nourish
the lung: in this orifice also are three valves (_hostioli_) opening
from within outward and closing from without inward, in the opposite
way to the valves of the other orifice; and this is so that they should
entirely close. Hence by this orifice the heart during the period of
contraction can expel, and yet during the period of its dilatation
cannot attract anything through it as was done in the first orifice.
The left ventricle of the heart has its sides denser and thicker than
the sides or walls of the right ventricle; and this for three reasons:
Firstly, because in the right ventricle is contained the blood, which
is heavy, while in the left ventricle there is spirit, which is very
light; therefore in order that the heart should not be heavier and more
ponderous on one side than on the other, it was necessary to compensate
in this manner, that is, that the left ventricle should be thicker in
its walls than the right. In the second place, the spirit being more
subtil and more volatile (_resolubile_) than blood, it needs a stronger
habitation and better supports. Thirdly, the left ventricle is much
warmer than the right, because in it is generated the spirit from the
blood, by a great heat which makes that blood more subtil; and heat is
better preserved in a substance that is dense and thick.
In the cavity of this ventricle near its root are two orifices: one is
the orifice of an artery called _artharia adorti_ [= aorta], because it
has immediate origin in the heart and because it is the source of all
the others: by this artery the heart sends the generated spirit to all
the members; and the very subtil blood is mixed with the spirit when
the heart contracts. For which reason there are at the entrance of this
orifice three valves, which close entirely from the outside inwards;
and they open from the inside outwards, and this orifice is very deep.
The other orifice is that of the _venal artery_ which conveys the air
from the lung to cool the heart and transports warm vapours from the
heart to the lung as has been said above; and in this orifice are two
valves which do not entirely close: and they are well raised so that
they can better apply themselves to the sides [edges] of the heart
when it sends out the spirit: these are marvellous works of nature,
as is also the central ventricle of the heart, for this ventricle has
not one cavity but many; these are small but wide, and more numerous
on the right than on the left; and nature contrived thus, so that the
blood which goes from the right ventricle to the left to be converted
continually into spirit becomes thin in these cavities.
And by this thou canst see that four things have birth in the heart.
The first is the artery called _adorti_, the second is the _vena
chilis_, the third is the _arterial vein_, and the fourth the _venal
artery_.
Also thou wilt see in the heart certain membranous parts like
_auricles_, or rather like small ears, able to dilate or contract:
these are contrived by nature in order that when overmuch blood or
spirit is generated the heart can dilate so as to contain it; and also
that the heart may contract when there is no such abundance.
And it is here that Galen asks, Why did not nature make the heart so
large that it could contain every increase of blood or spirit without
the addition of these membranes? Galen replies that this was first
because the heart would have been too large and therefore too heavy;
secondly, because as it is not always generating a great quantity
of blood and spirit, if the heart had been too large, its cavity
would usually have been empty: but these auricles dilate with the
accumulation of blood or spirit, and contract with its decrease.
The heart is surrounded by a firm and nervous membrane, like a
little house in which it is placed as in a tabernacle to defend it
from accidents. This capsule is very dilated, that the heart in its
dilations and movement may not be impeded thereby, and therefore nature
made this capsule so that it should contain a certain dewy moisture
with which the heart is bathed and moistened so that in its continual
movement it should not become dry. For when this water be dried up,
then the heart itself is desiccated, and emaciates and dries up all the
body.
* * * * *
The description of the heart follows Mondino closely. Occasionally a
phrase or two is reminiscent of Mondeville. The trite conception of the
heart as a king in its necessarily central position was very frequently
repeated by writers in the Middle Ages. To Harvey, who had a certain
mediaeval element in his mentality, it seems to have appealed, and he
used it in his _Prelectiones Anatomiae_,[202] and chose it to introduce
his great work on the circulation of the blood.[203] The heart was
similarly described as ‘flame-shaped’, because it was regarded as the
source of animal heat. The idea that it is the first to live and the
last to die comes from Aristotle.[204] The _bone_ in the heart also
comes from Aristotle.[205] The idea was quite familiar to mediaeval
anatomists, who frequently endeavoured to identify the _bone_ with the
firm tissue around the orifices of the aorta and pulmonary artery. The
reader may be reminded that a true ‘os cordis’ is in fact to be found
in some mammalia.
Mondino, followed by Manfredi, describes the action of the heart and
blood-vessels mainly according to the views of Galen, but without any
very clear or connected statement. The ‘third ventricle’ especially has
its origin in a misunderstanding.
This mythical structure is an attempt to combine the views of Aristotle
and of Galen. Aristotle, who probably never dissected a human body,
derived his anatomical conceptions largely from cold-blooded animals,
in some of which the heart is provided with three cavities. He
considered that the heart had three chambers, the largest being on the
right, the smallest on the left, and one of intermediate size between
the two. As far as they can be identified, the largest was the right
ventricle plus the right auricle, the smallest or left chamber was the
left auricle, while the intermediate cavity appears to have been the
left ventricle.[206]
Galen’s description differed altogether from that of Aristotle. He
tells us expressly and somewhat contemptuously that ‘it is no marvel if
Aristotle erred in many anatomical matters, a man who thought forsooth
that the heart in the larger animals had three chambers’.[207] Galen
always describes the heart as having but two chambers, the right and
left ventricles, a wholly subordinate part being assigned to the
auricles. These latter were regarded as safety-valves, expanding to
hold superfluous blood when the chambers of the heart to which they
correspond become overfilled.
[Illustration: Fig. 21. THE HEART