ANATOMY OF THE DRILL. 



445 



1. C'ommuuicating to the glosso-pharyngeal, accessory, hypo- 

 glossal, and sympathetic. 



2. Pharynyecd nerve (a) which breaks up into the pharyngeal 

 plexus in which it meets branches of the glosso-pharyngeal and 

 s^anpathetic. 



3. Sicperior laryngeal nerve (h) which gives off one external 

 branch and a brushwork of internal fibres, and the latter pierce 

 the thyro-hyoid membrane. No external branch connects it to 

 the I'ecurrent nerve, and no depressor nerve arises from it. 

 Communications unite it to the ganglion nodosum and carotid 

 plexus. 



No cardiac nerves are given off in the neck. 



Text-figure 20. 

 A. 



Lower cervical and upper thoracic parts of the vagus and sympathetic. D.C;P. and 

 S.C.P: deep and superficial cardiac plexuses; S.A.and V.A: subclavian and 

 vertebral arteries. Other letters in text. 



4.^ The right recurrent nerve (text-fig. 20, d) has the usual 

 origin, course, and relations. It communicates with the sym- 

 pathetic (S), but no branch connects it to the left recurrent 

 nerve (e). The latter has the usual course, but it does not com- 

 municate with the cardiac branches of the left vagus. 



5. Cardiac Nerves (/) :— The left vagus gives ofi" two large 

 branches to the superficial cardiac plexus, and these end in small 

 ganglia Avhich also receive sympathetic filaments. The right 



Proc. Zool. Soc— 1922, No. XXX, 30 



