Bauhaus-Universität Weimar

Titel:
The Cyclopaedia of Anatomy and Physiology, vol. 2: Dia-Ins
Person:
Todd, Robert Bentley
PURL:
https://digitalesammlungen.uni-weimar.de/viewer/image/lit25760/603/
HEART. 
tinuous with its inner coat. If we trace the 
inner membrane of the left side of the heart 
from the entrance of the pulmonary veins, we 
find that, after lining the auricle, it is continued 
through the auriculo-ventricular opening, and 
is there folded upon itself to assist in forming 
the mitral valve. In the left ventricle it sur¬ 
rounds the chordæ tendineæ and unattached 
columnæ cameæ in the same manner as in the 
right ventricle ; and at the origin of the aorta it 
assists in forming the semilunar valve, and be¬ 
comes continuous with the inner coat of the 
artery. These membranes adhere intimately to 
the inner surface of the heart by close cellular 
tissue, and have their inner surface perfectly 
polished and smooth. That of the left auricle 
is thicker than that of the right. They are 
thicker in the auricles than in the ventricles. 
In the ventricles, except near the origin of the 
large arteries, they are exceedingly thin. 
Nerves of the heart.—The heart is supplied 
with nerves from the sympathetic and par 
vagum. The sympathetic branches come from 
the superior, middle, and inferior cervical gan¬ 
glia, and frequently also from the first dorsal 
ganglion. The branches from the par vagum 
come directly from the trunk of the nerve, and 
indirectly from the recurrent or inferior laryn¬ 
geal. The course of these on the right side 
differs from those of the left in some respects, 
and requires a separate description. These 
nerves, like most of the other branches of the 
sympathetic, are very irregular in their size, 
number, and origin, so that it would be difficult 
to find two subjects in which they are exactly 
alike ; they are also very irregular in their 
course before they reach the cardiac plexus, 
but become more regular when they gain the 
arteries of the heart, whose branches they ac¬ 
company. These nerves, after forming diffe¬ 
rent anastomoses and plexuses with each other 
of the same side, converge at the upper and 
back part of the arch of the aorta, where they 
form a free anastomosis with those of the oppo¬ 
site side, and then pass on to the heart. The left 
cardiac nerves are sometimes much smaller 
than those on the right side, so as to appear, as 
in the dissection described by Lobstein,* merely 
accessory to those on the right. On the other 
hand the size of those on the left side may pre¬ 
ponderate considerably over those on the right. 
The proportional size of the different nerves of 
the same side is also very various. When the 
nerves of one side are small, the deficiency is 
made up by the greater size of those of the op¬ 
posite side ; and when any particular branch is 
either unusually small or entirely wanting, its 
place is supplied by the greater size of the 
other nerves of the same side, or of those of the 
opposite side. The branches from the par 
vagum, particularly those coming from the re¬ 
current, vary also considerably in size. All 
the sympathetic branches of the cardiac plex¬ 
uses are of a gray colour, and are generally not 
so soft as Scarpa has described them. 
The right cardiac branches of the sympathe- 
* De Nervi Sympathetici humani fabrica, &c. 
pp. 16 & 18. 
tic are generally three in number : 1st, superior 
cardiac (supremus et superficialis cordis) arises 
from the lower and inner part of the superior 
cervical ganglion, or from the continuation of 
the sympathetic between the superior and 
middle ganglia, or from both these origins. It 
generally also receives a filament from the par 
vagum. In its course down the neck it lies 
behind the sheath of the carotid artery. It 
anastomoses with the external laryngeal nerve 
and descendens noni, and sends a twig along 
the inferior thyroid artery to the thyroid body ; 
and at the lower part of the neck it sometimes 
divides into two branches as figured by Scarpa,* 
one of which unites itself to the middle car¬ 
diac, the other forms an anastomosis with the 
recurrent nerve of the same side. At other 
times it passes into the thorax either in front or 
behind the subclavian artery, takes the course 
of the arteria innominata, and reaches the pos¬ 
terior part of the arch of the aorta, where it 
anastomoses with branches of the middle and 
inferior cardiac nerves, or with branches of the 
recurrent. It more rarely appears to pass to 
the eardiac plexus without any anastomosis 
with the middle and inferior cardiac branches. 
It frequently presents a ganglion in its course 
down the neck. 
Middle cardiac nerve—This nerve arises by 
several short twigs from the middle cervical 
ganglion. This is generally the largest of the 
cardiac nerves, and is named by Scarpa the 
great or deep cardiac nerve (n. cardiacus mé¬ 
dius, s. profundus, s. magnus). It proceeds 
downwards and inwards, crosses the subclavian 
artery, sometimes in front, at other times it di¬ 
vides into several branches, which surround the 
artery and again unite. It anastomoses with 
the branches of the recurrent, in the neigh¬ 
bourhood of which it runs, also with the par 
vagum, superior and inferior cardiac nerves ; 
and following the course of the arteria innomi¬ 
nata it passes behind the arch of the aorta to 
terminate in the cardiac plexus. 
Inferior cardiac nerve (n. cardiacus minor 
of Scarpa).—This nerve generally arises by fila¬ 
ments from the inferior cervical ganglion, some¬ 
times from the first dorsal ganglion, at other 
times from both. It proceeds behind the sub¬ 
clavian artery near to the recurrent nerve. It 
follows the course of the innominata close to 
the middle cardiac, with which it anastomoses, 
and proceeds to join the cardiac plexus. 
Left cardiac nerves.—Perhaps the differences 
in the course of the right and left cardiac nerves 
are principally to be attributed to the known 
differences between the large arteries of the two 
sides. The left superficialis cordis is figured 
by Scarpaf as dividing a little above the arch 
of the aorta into four branches ; two of these 
pass in front of the aorta to form an anastomo¬ 
sis with a branch of the par vagum and deep 
cardiac ; a third also passes in front of the aorta 
to unite itself with the middle cardiac; and the 
remainder of the nerve proceeds behind the 
arch to unite itself with the cardiac plexus. 
* Tab. iii. Tabulae Neurologieae, &c, 
t Tab. iv. op. cit. 
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