1881.] 1^^ [Stowell. 



laryngeus inferior dexter bends around A. subclavia, just dorsad of A. 

 sternalis, a branch is given ofFcaudad, which, 10-12 mm. from its origin, 

 joins N. cardiacus minor (Fig. 10), and these apposed trunlvsare joined 5 

 mm. periplierad by N. cardiacus magnus dexter, and |,the trunk tlius con- 

 stituted passes dorsad of V. cava descendens and A. innominata to the 

 dorso-caudal border of the arch of A. aorta, where it terminates in Px. mag- 

 nus profundus, from whicli tilaments proceed to tlie ventral and dorsal 

 coronary and the pulmonary plexuses. 



Traclieo-ceso'plMgeal rarnuli of N. laryngeus inferior (Fig. 11, 12). 

 General characters: these ramuli of the sinistral and dextral nerves 

 have in common the following characters — their origin; general direction; 

 numerous terminal filaments; the plexiform relation of these filaments; 

 their mode of entering larynx; their distribution upon its mucous mem- 

 brane; distribution of the dorsal filaments to oesophagus. Distinctive 

 characters : the smaller number of ramuli from the dextral side than from 

 the sinistral; the homologue of the first sinistral nerve is always found as 

 a ramulus from the main trunk caudad of the origin of N. laryngeus in- 

 ferior dexter (Fig. 12); the terminal filaments of the dextral side are less 

 numerous than those of the corresponding nerves of the sinistral side.* 

 Special description : opposite the cephalic border of the arch of A. aorta 

 the first tracheal ramulus is detached (Fig. 11, lOrm.) ; a considerable offset 

 is directed caudad from the origin to Px. magnus profundus; 2 mm. 

 periplierad of origin an anastomotic filament joins N. vagus 8 mm. caudad 

 of origin of N. laryngeus inferior; 6 mm. periplierad of origin the ramulus 

 bifurcates, the longer division is distributed upon the dorsum of the 

 trachea 30 mm. cephalad of the arch of A. aorta; the shorter or caudal 

 division sends filaments to Px. cardiacus ventralis, to Px. magnus profundus 

 and to the bronchioli. 



Five mm. cephalad of the first ramulus a second is given to the venter and 

 the sides of the trachea over that portion corresponding to the distribution 

 of the cephalic division of the first ramus upon the dorsum. 



Ten mm. cephalad of the second ramulus and nearly opposite the origin 

 of A. sternalis, the longest ramulus is detached ; this divides into three 

 offsets, the caudal is distributed to the venter of the oesophagus, the 

 median to the sides of tlie trachea, the cephalic lies just laterad of the 

 ventrimeson and gives two considerable fasciculi, whose terminal filaments 

 supply the walls of the trachea ; the terminal filaments of the ramulus 

 are traceable nearly to Ctl. cricoidea. 



Opposite the sixth cervical vertebra the fourth ramulus is detached, 

 whose filaments anastomose with the preceding ramulus, and supply the 

 dorsum of the trachea and venter of adjacent oesophagus along the entire 

 cervical region from the thorax to the larynx. 



The fifth tracheal ramulus takes its origin 10mm. caudad of Ctl. cricoidea 



* The double ramuli sometimes occur with separate origins; this apparent 

 increase of ramuli may be regarded as a modification and not a violation of the 

 plan. In the special description the details of measurements of a single speci- 

 men are given. 



