BECT. 212.] VESSELS AND NERVES OE HEART. 48 1 



very numerous, but differ in nothing from those of the transversely 

 striated muscles (§ 83), except that, on account of the thinness 

 of the fibres, the capillaries often surround several of them to- 

 gether. The endocardium is tolerably rich in vessels in its outer 

 layer, but they extend sparingly ouly into the endocardium pro- 

 per. In the auriculo-ventricular valves of animals, as also of man 

 {vide Luschka, I.e. p. 182 and fig. 5), some small vessels are readily 

 seen, which partly reach them from the papillary muscles, but 

 chiefly from the base ; some few of these are distributed scantily 

 in the proper endocardial covering of the valve. According to 

 the recent observations of Luschka, even the semilunar valves 

 are provided with vessels. — But few lymphatics occur upon the 

 parietal layer of the pericardium ; on the other hand, they are 

 present in large numbers upon the muscular substance beneath 

 the visceral lamella, and can be easily demonstrated, as Cruik- 

 shank pointed out, when the heart is allowed to lie in water for 

 some days. Their trunks collect in the grooves, run with the 

 blood-vessels, and terminate in the glands behind and beneath 

 the arch of the aorta at the division of the trachea, where thev 

 meet the lymphatics coming from the lungs. It is not yet deter- 

 mined whether the cardiac substance and the endocardium possess 

 lymphatics, as is stated by some authors. — The nerves of the 

 heart are numerous, and come from the cardiac plexus (beneath and 

 behind the arch of the aorta), which is chiefly formed by the vagus 

 and sympathetic. They proceed with the vessels to the right and 

 left auricles and ventricles as the two coronary plexuses, of which 

 the left is much larger than the right : hence they run towards 

 the apex of the heart, partly accompanying the vessels, partly 

 crossing the direction of them ; then, after forming numerous 

 anastomoses, mostly at acute angles, they dip into the muscular 

 substance, some of them entering by the coronary furrow, and 

 thus they arrive at their places of distribution, viz., the muscular 

 tissue and the connective tissue of the endocardium. The cardiac 

 nerves of man are mostly grey, and, with the exception of the 

 largest, contain only fine and very pale nerve-tubes ; but these arc 

 in great numbers, and are intermingled with a small number of 

 nucleated fibres. Although the nerves, even in the endocardium, 

 are dark-bordered and pretty abundant, yet it has not been possible 

 hitherto to discover their terminations in this place any more than 

 in the muscular substance. In the pike, however, Martin has 

 observed them to end by dichotomous division with free termina- 

 ions, in the muscular substance of the heart [Gott. Nachr. 1853, 



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