On the Aortic Nerves in Dogs

The depressor or aortic nerve was anatomically and physiologically investigated in dogs. The nerve which is capable of causing reflexly a blood pressure fall and a pulse retardation was discovered in all the cases in the left side. The nerve in the right side whose course is wholly the same as the left nerve, acted in the same manner, though in a somewhat inferior strength roughly speaking, in about two thirds of cases, while in the rest it was impossible to elicit any reflex so far as the circulatory system is concerned. In a few cases a pressoric action was registered. The aortic nerve has its root from the upper laryngeal nerve orthe vagus, near it, or two roots from both, or. some such place, which unite sooner or later. The aortic nerve then Joins downwards invariably to the vagus or sometimes to the sympathetic-trunk after running isolated, commonly for a few centimeters. In order to isolate the depressor the common sheath of the vagus and sympathetic must be carefully opened. The. aortic nerve thus prepared has usualy a sufficient length for stimulation with induction currents. In the upper thoracic cavity the aortic nerve branches from the vagus in the neighbourhood of the median cervical ganglion on the left side, and of the branching of the recurrent nerve on the right side, and runs towards the aortic arc, to the ventral respectively to the dorsal wall. In two cases, which were all those which we especially investigated, the depressor fibres in the aortic nerve prepared in the thoracic cavity were proved as contained in the aortic nerve prepared at the upper neck.