HEART. 
“refponding to the auricle, is ee the auricular ; the other, 
correfponding t Fee dso onary artery; is named the arterial ; 
oné of the other two portions ts turned downwards and for- 
wards, towards. che inferior furface and fharp edge of the ven- 
tricle: the other is placed backwards and to the left, to- 
wards the fe tum. 
- This valve is made up of two ere layers adhering 
ceedcan = the aepeaed of the tendinaus threads on 
their furface. 
’ The ufe of this valve is to prevent the blood from flowing 
back again into the auricle w yhen the ventricle contraéts: 
= againft the fide of the cavity, where the blood paffes 
ugh the auricular opening; but when the ventricle 
qoutes the three portions are raifed from thie fitua- 
tion, and meet together fo as to clofe the opening: thefe facts 
may be obferved by injecting any fluid in the dead fubje& 
contrary to the courfe of the blood. 
The arterial opening of the right ventricle (oftium arterio- 
fum) is much fmaller than the preceding, and is marked 
callous ring (tendo cordis arteriofus’, which terminates die 
aefhy part of the heart, and marks out the origin of the artery. 
We have already defcribed, in the account of the arterial fyf- 
pd 
es how the art ery and ventricle are united. Theentrance of - 
the pulmonary artery is furnifhed ithree valves, called the 
.figmoid or femilunar, which exa@ly refemble, in their ftruc- 
ture and difpofition, the valves of the veins deferibed in a> 
former part of this article. As they are defigned to prevent 
the reflux of the blood towards the heart, their attached 
edge is turned towards the ventricle, and their loofe margin 
i 
thefe valves is completely mechanical, and may be obferved 
in -~ déad body by injeéting contrary to the blood’s courfe. 
lie againtt the fide of the artery, where the ventricle 
contracts ; and are fo thin as not to interfere with the tranf- 
miffion of the blood through the opening. When any fluid 
comes in the oppofite direction, it raifes their loofe edges, 
fills the facs intercepted between the valves and the artery, 
and preffes the eaten together, fo as completely to prevent ' 
paflage in this un courfe, 
The left ventricle i is "bn er than the righty and extends ra- 
ther further at the a s figure is that of 
upper an 
The 2 apex is obtuly and forms the largeft- part "of 
= point of the heart : the bafis is joined to the correfpond- 
mg auricle. "Phe upper and right part gives origin to the 
The cavity of this ventricle prefents the fame three kinds 
of mufeslar columns as have mentioned in the a 
= of the — Sie: OF the-Geft:- kidd Sere larger but lefs 
he right ventri iéle : their apices are more 
renee or -_— divided into three portions. 
The ny of 
us hewade-ase 
a to that sf hecolned 
Ke manner, 
————- and are of a fize 
ns. They. 
and are attached to the oofe edge 
diverge ina fan- 
the mitral 
‘fices correfponding to thofe of the o 
valve ; but fome are connected to the fides’ of the ventricle. 
Of thote, which are attached to the valves, foe pafs without 
any alteration from their orgie to their ieifertion : others di. 
vide into ercral branches, and fome communicate together 
fo as to form a kind of net-work, The length of thefe 
‘threads is not uniform: fome exceed an inch, while others 
are more th 
the fecond and third kinds are much lefs numerous and lar 
7¢ 
an two or three lines i in length. - “The columns of 
or 
They are altogether. deficiewt 
han in the right ventricle. 
‘near the orifice of the aorta, vies the furface of the ventri- 
cle is fmooth. ‘The bafis of this yentricle soy de two ori- 
VIZ 
The auriculir orifice, (oftium venofum, ) ae than that 
re sag right ie is bounded like it by a kind rs whitifa 
» from which there is a membranous produétion, de- 
festa’ into the cavity ‘of the ventricle, nbgortoe it is divided into 
two portions, and confequently named t 
in all the effential parts ofits contrastion, refembles the tri- 
cufpidal ; like that it has two furfaces, one turned towards 
the fides of the cavity, and the — tow vis the auricular 
the adherent one is 
ren e latter margi 
conitantly divided into two portions, an inferi 
a fuperior and larger one, cortefponding to the mouth of the 
oe which it covers almoft entirely, when the ventricle is 
dilat 
The letter is the valvular feptum of Lieutaud, who con- 
ecives that it divides the cavity of the ventricle into an auri- 
an arterial portion. Between thefe two pore 
sie the see valve is not more than one or two |i 
roa mitral valve is confiderably thicker than the 
tricufpidal, id often befet at its loofe edge with fmall, cal- 
lous, and hard tubercles. Its ufe is jut the fame on the 
left, as that of de rpg: og valve is on the right fide of 
the heart. 
BE 
"heir off ice is jut the Henig in the — as that of hie 
in the pulmonary arte * of the aorta, teehee 
to the sia of the valon: Save Site tds {mall tumours, 
and there ne fame number of fmall cavities on the infide, 
called the frmall f wi il of the aorta; as thefe do not exift in 
the foctgs, they may be confidered to’ arife from the efforts 
of the blood againft the veflel. 
The two ventricles are feparated by a mufcular partition, 
which is thickeft at the bafis, and grows gradually thin- 
he} rt. In this the 
inter hich were confidered by the older-anato- 
milts to be openings of ee between ¢ tye: 
ties. The latter opin 
the partition is allowed to 
It has been the paieraly pone opinion, sia the saiphe 
ventricle 
mitral valve, which, | 
ie 
or and f{maller, 
