194 



CIRCULATORY SYSTEM. 



the apex, goes along the superior fissure of the septum of the 

 ventricles, and then winds to the left side, between the left au- 

 ricle, and the left ventricle: while in the latter position, it is 

 joined by several trunks coming from the left ventricle and the 

 left auricle: it, finally, empties into the lower part of the right 

 auricle, just in front, as mentioned, of the orifice of the ascend- 

 ing cava; being there covered by its own valve. 



The Lesser Coronary Vein (Vena Coron. Minor Cordis) lies 

 in the inferior fissure of the septum of the ventricles. It be- 

 gins at the apex, and, going backwards, collects the blood from 

 the flat surface of the heart, principally on the right ventricle. 

 It discharges into the great coronary vein, just before the latter 

 terminates in the auricle. 



Besides the preceding veins, some of a smaller size exists on 

 the right ventricle and auricle, and about the root of the aorta 

 and pulmonary artery, and empty by several orifices into the 

 right auricle. There are also some veins of a still smaller 

 size, which open into all the cavities of the heart by little ori- 

 fices, called the Foramina of Thebesius: by Mr. Abernethy 

 they are considered as being larger when the lungs are dis- 

 eased.* 



The Nerves of the Heart come principally from the cervical 

 ganglions of the sympathetic, and follow the course of the coro- 

 nary arteries. It has been doubted whether these nerves are 

 actually distributed in the substance of the heart, from the pre- 

 sumption, that as they cannot be traced beyond the third order 

 of branches of the coronary arteries, they are limited to them. 

 But, as the ramifications of the sympathetic are bestowed exclu- 

 sively upon the branches of the circulatory system, Meckel has 

 very properly suggested, that the heart being also supplied with 

 nerves from the same source, it follows that there can be no de- 

 parture from the general rule, as the heart is nothing more than 

 the fibrous portion of the blood vessels more completely deve- 

 loped. 



While the circulation continues, as both auricles contract at 



* London Philosophical Transactions, 1798. 



