3 H & A B.-Ti 
The left auriclé, rather fmaller than the right, has nearly 
the figure of a cube, and offers fix fides to our confideration. 
The anterior is connected to the bafis of the left ventricle : 
The four pulmonary veins, of which two are on each fide, 
open into the upper and back part of the auricle. The two 
of the left fide are the moft eafily feen in the pericardium : 
the right are concealed by the fuperior cava, and by the 
she’ 
neighbouring part of the right auricle: 
oppofite fide. The inferior and external fides are fmooth, 
and, as well as the reft of the auricle, prefent no columns. 
The fides of the auricles have very litle thicknefs: thofe 
i left emi- 
continuous with the lining of the veins, and of the ventricles, 
i been i The mufcular fibres are ge- 
nerally torn when we attempt to feparate them from the mem- 
brane between which they fie and are fo intricately inter- 
woven with each other, that it would be as difficult as ufelefs 
to attempt at unravelling and minutely defcribing their ar- 
rangement. : ; 
_ The right ventricle refembles a ‘triangular pyramid, and 
ofers for our obfervation a fuperior, an inferior, and a left 
furface ; a bafis and an apex. i 
derab 
i > . 2 ri 4 all {peak below. 
’ The bafis is joined to the left auricle; the fuperior and left 
Qn the interior the left furface is formed by the feptum, 
which is thicker towards the bafis than the apex of the heart, 
and pose by no opening. The fuperior, inferior, and 
left furfaces, are tolerably {mooth towards the bafis of the 
heart » but in the reft of their extent they exhibit a great 
numbér of flefhy columns. (column carnex )s formed by the 
moit interior fibres of the ventricle, and varying much in fize, 
length, and direction. ‘Three kins of thefe columns may be 
diftinguifhed. Thofe of the firft fpecies are fixed by one 
extremity to the fide of the yentricle, and by the other to the 
fe edge of the tricufpidal valve, by means of fmall tendj. 
nous threads (chord tendinee.),. The columns of the fe. 
; ae : 6 : cee 
cond kind are attached by both ends to the ventricle sane”. 
thofe ef the third are fixed in their whole length.. 
their points, bifurcated or divided into three y give 
origin to feveral tendinous threads, which diverge like the 
branches of a fan, are, for the moft- part, attached to the tri- 
cufpidal valve, but terminate partly in the fides of the ventri- 
cle. Some of thefe communicate together ; and they are fome- 
times feen to pafs from one column to another. The tendi- 
nous threads either go ftraight to the valve, or they are di- 
vided in their progrefs into fmaller filaments: the fhorter 
ones terminate on the loofe edge of the valve, while the 
longer are continued for a greater or lefs extent upon that 
furface of the valve, which is turned towards the fide of the 
ventricle. ‘ 
‘The fecond clafs of columns occupies particularly the an- 
terior or lower third of the ventricle, and is tolerably nume- 
rous ; they decuflate each other, and are varioufly conneéted, 
fo as to form a kind of net-work. Thofe of the third kind 
are the moft numerous: they have every variety of fize and 
direétion, and conneétion to each other, fo as to render nearly 
: : Beier rs 
of cavities, or of compa eet 
ing of the mufcular fafciculi, of which the number is very 
great. : i 
The bafis of the right ventricle has two openings; of 
which the largeft, placed downwards and to the righty forms 
its communication with the auricle, and is called th auricu- 
ror auriculo-ventricular orifice (oftium venofum)+ the 
other, fmaller and hi i i 
"Thele are feparated by an interval of about an inch. © 
tricufpidal or triglochine, formed by a circular fold of mem- 
brane produced E 
wards the fides of the ventricle, and the other towards the 
a 
auricular orifice. The adherent edge is attached to the 
ready defcribed, and is divided into feveral pointed por at at | 
5 : pe 5 tare 
which are however almot conftantly more confpicuo eer 
the others, fo as to have given a name’ to the valve? poe 
divifions one, confiderably broader and longer than sep 
is p upwards and ferwards, towards the oriliee < fei 
meafurey ¥ a 
pulmonary arte: ze which it covers in great pajapee >: 
it is applied. an the fide of the ventricle. This is nanoed 
y Lieutaud the valvular feptum, and is reprefente 
h 
Leo 
ed. by Bit 
to feparate the. ventricle into two cavities, of whi ai 4 
