THE NERVOUS SYSTEM 155 



(v) A sensory branch to the mucous epithelium of the pharynx and 

 mouth leaves the recurrent nerve close to the foregoing branches on 

 the ventral side of the M. cephalo-dorso-subpharyngeus. It passes 

 dorsalwards to the floor of the pharynx between the pulmonary arch 

 and the above-named muscle. It is relatively of fair size, and corre- 

 sponds with the recurrent branch of the fourth and fifth visceral 

 nerves and, like them, passes dorsal to the arterial arches. 



The remainder of the nerve then turns anteriorly and remains 

 ventral to the arterial arches. It passes very close to the truncus 

 arteriosus, and, at about the level of the pulmonary arch, it gives off: 



(vi) A fine anterior cardiac nerve (n.c.a.) to the truncus arteriosus. 

 The residue of the nerve is now: 



(vii) Thei?. muscularis for the M. subarcualis rectus I. It passes 

 anteriorly and fuses with the corresponding branch of the fourth vis- 

 ceral nerve, and with that of the fifth visceral nerve also — when such 

 is present. 



Driiner reports that a large number of ganglion cells are to be 

 found in the region of the R. recurrens, both ventral to the muscles 

 and on the branches to the mucous epithelium. 



These various branches of the recurrent nerve are somewhat diffi- 

 cult to dissect owing to their small size and rather pale colour. The 

 dissection is best carried out from a ventro-lateral aspect. The cucul- 

 laris muscle must be removed and the M. rectus cervicis pulled over 

 ventrally, and then the nerves may be detached from the connective 

 tissue in which they are embedded. 



(/) From the intestinal trunk immediately posterior to the recur- 

 rent nerve is given off to the larynx a fine branch which is here 

 named dorsal laryngeal nerve (n.lar.d.). It appears to have been over- 

 looked by Druner since he does not mention it in his paper. Its 

 position relative to the M. dilatator laryngis appears to vary some- 

 what, since it has been found both anterior and posterior to the 

 muscle. In either case, however, it passes mesially, closely applied 

 to the wall of the pharynx, and dorsal to the laryngeal artery. 

 Although it appears to terminate in the M. constrictor laryngis and 

 sends a branch to the dilatator muscle, its translucent appearance and 

 close relation to the pharyngeal wall would lead one to suspect that 

 it is probably in the main a sensory nerve to the larynx. 



The intestinal nerve divides into pulmonary and gastric branches 

 almost immediately after giving off the branch just described. 



{g) The common pulmonary nerve (n.pul.) is the more ventral of the 

 two and soon divides again into two. 



(i) A lateral pulmonary nerve (n.pul.l.), which accompanies the 



