1881.] 1^^ [Stowell. 



NN. laryng-ei inferiores, recurrent or inferior branches of N. • 

 vagus, tracheal recurrents, have the following general eliaracters in com- 

 mon, viz.: their general cephalic direction; their disposition along the 

 dorso-lateral border of the trachea; the anastomotic character of their 

 ramuli ; the distribution of the terminal filaments; the sensory function of 

 the fibre. Distinctive characters: their origin; their length; their disposi- 

 tion in the thorax; the relative number of anastomotic filaments; the num- 

 ber of tracheo-cesophageal ramuli. 



Special description : N. laryngeus inferior sinister, the sinistral re- 

 current nerve, branches from the mesal aspect of the main trunk of N. 

 vagus, 1-3 mm. cephalad of the arch of A. aorta (Fig. 9, 45);* its course 

 is caudad, apposed to the mesal side of the main trunk as far as the root 

 of A. subclavia sinistra where the main trunk crosses the arch of A. aorta. 

 Upon the ventral aspect of the arch of A. aorta, N. laryngeus inferior sep- 

 arates from the main trunk upon the mesal side, and twisting around the 

 concave aspect of the arch about 1 mm. sinistrad of the obliterated 

 "ductus arteriosus," it trends meso-dorsad, and returns cephalad along 

 the dorso-lateral border of the trachea, between the trachea and the oeso- 

 phagus, as a "recurrent nerve" (Fig. 9, 50). At the caudal border of the 

 larynx N. laryngeus detaches several ectal filaments to M. crico-thyroideus 

 (Fig. 8), passes entad of a caudal twig of A. thyroidea superior, bends 

 dorsad around the articular facet ofCtl. ci'icoidea (Fig. 8) and enters the 

 larynx as an ental nerve. A slender anastomotic twig passes ectad of the 

 arterial twig named and may be traced dorsad of the nerve trunk until it 

 joins a corresponding twig from the caudal division of N. laryngeus su- 

 perior (Fig. 7, 29, a). Pharyngeal ramuli from the ental nerve are dis- 

 tributed to M. constrictor pharyngis inferior; other dorsal filaments supply 

 M. arytfenoideus posterior and M. arytienoideus; ventral filaments supply 

 MM. crico arytienoideus lateralis and thyro-arytsenoideus, while terminal 

 filaments reach the sub-glottic mucous membrane. Upon the ectal surfaces 

 of MM. crico-arytoenoideus posterior and crico-arytsenoideus lateralis a 

 multiple palmate plexus is formed by anastomotic filaments of NN. 

 laryngeus superior and laryngeus inferior (Fig. 8, 4.I). 



N. laryngeus inferior dexter is detached from the main trunk of 

 X. vagus, 13 mm. cephalad of the origin of A. subclavia, where the main 

 trunk is disposed upon the ventral aspect of A. subclavia (Fig. 10) ; N. 

 laryngeus dexter is immediately directed caudad over the venter of the 

 artery, is reflected around the caudal aspect, and assumes a meso-dorsal 

 direction to the dextral side of the trachea, and is disposed like its sinistral 

 homologue, with the exception of having fewer anastomotic filaments. 

 Peripherad of the origin of N. laryngeus inferior dexter, dorsad of A. sub- 

 clavia, ramuli are given to the deep cardiac and the posterior pulmonary- 

 plexuses; another ramulus cephalad joins its sinistral fellow, a third, the 

 thoracic cardiac, is directed caudad by the side of the main trunk of N. 

 vagus dexter, and terminates in the dextral bronchial plexus. As N. 



* An oecasioual origin is 8-10 mm. cephalad of cephalic border ot arch of A. 

 aorta. 



