206 THE ANATOMY OF THE HORSE. 



inwardly the 9th nerve. It gives branches to the pharynx, and is con 

 tinned to the soft palate. 



The 9th or Glosso-pharyngeal Nerve descends on the guttura 

 pouch, behind the great cornu ; and crossing to the inner side of th( 

 external carotid- artery, it gives off its 'pharyngeal hratich. This tumf 

 round behind the stylo-pharyngeus muscle, and ramifies on the pharynx 

 meeting there the pharyngeal branches of the 10th and sympathetic 

 nerves, and forming with them the pharyngeal plexus. 



Nerve to the Stylo-pharyngeus. — This is a special branch of the glosso 

 pharyngeal, given off either from the trunk of the nerve or from iti 

 glossal continuation. It enters the muscle at the middle of its outei 

 face. 



The Glossal Continuation of the 9th nerve passes over the hyo-pha 

 ryngeus and palato-pharyngeus to reach the base of the tongue ; and ii 

 its course it detaches fibres which are probably motor to the palato 

 pharyngeus, hyo-pharyngeua, cerato-hyoid, and hyoideus transversus. 



For the pharyngeal branches of the 10th and sympathetic nerves sei 

 pages 194 and 195. 



Directions. — The pharynx is to be opened by an incision along iti 

 lateral aspect, when, by hooking back the edges of the incision, a viev 

 of its interior will be obtained. 



The Pharyngeal Cavity (Fig. 24, page 217) is irregularly tubular i] 

 form, and presents seven openings. These are : — 



1. The Isthmus of the Fauces, already described (page 202). 



2. The Superior Nares (2), situated vertically over the isthmus, fron 

 which they are separated by the soft palate. They are wide, gaping 

 orifices, with rigid bony margins. 



3. The Lower Openings of the Eustachian Tubes (2), which are situatec 

 on the sides of the pharynx, behind and in line with the superior nares 

 The opening has the form of a vertical slit, the outer edge of whicl 

 contains the cartilaginous extremity of the tube. 



4. The Upper Aperture of the Larynx. — This is placed on the floor o 

 the pharynx, and has the form of a pitcher-mouth. During deglutitioi 

 the epiglottis folds over it like a lid, but at other times it is a larg 

 patent orifice. 



5. The (Esophageal Orifice. — At the posterior end of the pharynx, it 

 cavity is continued into the lumen of the gullet. Except during th 

 passage of solids or fluids, however, this orifice is not open. 



Mucous Membrane. — This lines the cavity completely, and is cor 

 tinuous through the before-mentioned orifices with the lining membran 

 of the mouth, nasal chambers, Eustachian tubes and guttural pouchef 

 larynx, and oesophagus. It has a stratified squamous epithelium, excef 

 in its upper and anterior part, where it is ciliated. It has man 

 mucous glands. 



