HEART. 



59i 



tinuous with its inner coat. If w 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 chordae tendineae and unattached 

 columnae carnese 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 Sympathetic! 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 

 vagura. 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 cardiac 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 me- 

 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 innomt- 

 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 Neurologic*, &e, 

 f Tab, iv. op. cit. 



2R 2 



