86 



PRACTICAL ANATOMY. 



of the pharynx and prevents regurgitation of ingesta into the mouth, thereby 

 enabling the constrictors of the pharynx to grasp the bolus to be swallowed. 



7. What muscle lies under tJie fold of mucous membrane of the posterior pillar 

 of the fauces ? 



The palato-pharyngeus. This muscle is inserted into the superior cornu of 

 the thyroid cartilage, and also into the fibrous part of the pharynx. The action 

 of this muscle is to assist deglutition by elevating the pharynx by stretching 

 the pharynx over the bolus, as it were. 



The act of swallowing may be compared to a most delicately acting cylinder 

 and piston : The tongue is the piston ; the isthmus of the fauces, the cylinder 

 in which the piston plays ; the junction between the pharynx and the oesophagus 



Infraorbital artery and nerve 



Orbital branch. 



Nasal branch 

 Anterior 

 dental branch I 



Labial branch \ 

 Posterior dental 

 branch 



Incisive branch 

 Mental branch 



Submental branch 



Spheno-palatine branch 



Posterior, or descending palatine branch 

 Naso-palatine branch 



Vidian branch 



A nterior deep temporal artery 

 External pterygoid branch 



I Posterior deep temporal artery 



Small meningeal 

 artery 



Middle meningeal 

 artery 



Temporal artery 

 Tympanic branch 



Deep auricular 



branch 



AriiH'ULO-TEM- 

 PORAL XEKVK 

 Masseteric branch 



External carotid 

 artery 



Internal lateral or 

 spheno-mandibu- 

 lar ligament 



Afandibular or 

 inferior dental 

 artery and nerve 



Succal branch with Internal pterygoid branch 

 portion of buccal nerve 



Mylo-hyoidean branch 



FIG. 51. SCHEME OF INTERNAL MAXILLARY AKTI.KY. 



is the escape. The digastric and stylo-hyoid muscles elevate the tongue ; at the 

 same time the palato-glossus draws the tongue backward, piston-like, through 

 the isthmus, thereby preventing regurgitation and at the same time pressing 

 onward the food. At this juncture the palato-pharyngeus muscle depresses the 

 soft palate, thereby aiding the preceding muscle, and at the same time pulls up 

 the pharynx, just as one pulls a stocking on. 



S. \VIiat would be tlie result were the poloto-pkaryngfUS muscle paralyzed, and 

 do such circumstances arise in the practice of medicine / 



The result would be loss of the delicate part of the act of swallowing. 

 Solids would find their way to the stomach, but fluids, more difficult to grasp, 

 l>y the constriction of the pharynx would regurgitate through the nose, under 



