B. THE PHARYNX, BY E. KLEIN. 527 



mucosa pursue various directions, but those of the submucosa 

 are chiefly directed downwards. 



The acinous glands of the pharynx, especially in the middle 

 and lower parts of the upper third, form groupsj the excretory 

 ducts of which open with wide orifices. The individual glands 

 are oval, with their long diameter parallel to the long axis of 

 the tube. In the lower third they diminish considerably in 

 number, so that at the upper part of this they only occur in an 

 isolated condition, whilst below they are but rarely met with. 



The depth of the mucosa varies with the thickness of the 

 glandular layer, but diminishes gradually in the lower third 

 towards the oesophagus. The larger nerve trunks lie in the 

 submucous tissue, and run for the most part in a longitudinal 

 direction, whilst their branches form a deep and a superficial 

 plexus, in the latter of which Remak* and Billroth observed 

 the presence of microscopical ganglia. 



The lymphatics of the pharynx are numerous, and, according 

 to Teichmann/f- are directly continuous with those of the nose, 

 oral cavity, trachea, and oesophagus. 



The outer fibrous layer of the posterior wall of the pharynx, 

 attached above to the base of the skull, extending downwards, 

 and containing a median tendinous fasciculus which arises 

 from the tuberculum pharyngeum, consists chiefly of strong 

 parallel bundles of fibrous tissue, with a variable amount of 

 finer and broader elastic fibres. These for the most part de- 

 scend obliquely with the fasciculi accompanying the nerves 

 and bloodvessels, and with others derived from the submucous 

 layer form sheaths for the pharyngeal muscles, and give off the 

 secondary septa for the smaller muscular fasciculi. 



The muscular layers of the posterior, and partly also of the 

 lateral, walls of the pharynx are so arranged as to form an es- 

 sentially circular external and an internal longitudinal layer. 

 The former is composed of the Constrictores pharyngis, the 



* Remak, Ueber peripherische Ganglien an den Nerven des Nahrungsrohres^ 

 Miiller's Archiv, 1856, p. 189 ; " On the Peripherie Ganglia of the Nerves 

 of the Alimentary Canal." A contest respecting priority with Meissner, in 

 which it was shown that Remak had previously, in 1840, found ganglia in 

 the tongue and on the pharyngeal branches of the Glosso-pharyngeus. 

 Loc. cit. 



