THE ALIMENTARY CANAL. 231 



Origin from the surface of the body of the sphenoid mediad 

 of the groove for the Eustachian tube, from the styliform 

 process of the bulla tympani, and in part from the Eustachian 

 tube. The muscle passes caudad, and its fibres then diverge 

 into the velum palatinum. 



Insertion into the velum palatinum, some of the fibres 

 meeting in the middle line. 



Action indicated by the name. 



A number of other muscles have been described in the soft 

 palate of the cat ; they are, however, poorly developed and not 

 easily distinguished. For an account of these, see Stowell, 

 Proceedings of the Am. Soc. of Microscopists, 1889. 



2. The Pharynx. At the caudal end of the mouth cavity 

 the passage for the food and that for the air cross; at the 

 cranial end the food-passage (mouth) is ventral, the respiratory 

 passage (nasal cavity) dorsal. Farther caudad the food-passage 

 (oesophagus) is dorsal, while the respiratory passage (larynx 

 and trachea) is ventral. In the region of crossing there is 

 therefore for a certain distance a common passageway for food 

 and air, and this is known as the pharynx. It extends from the 

 isthmus faucium, at the free caudal margin of the soft palate, to 

 the beginning of the oesophagus, at the dorsal or caudal margin 

 of the opening of the larynx. The dorsal wall of the pharynx 

 is separated from the base of the skull and the centra of the 

 cervical vertebrae only by intervening muscles (longus capitis, 

 levator scapulae ventralis, and longus colli, Fig. 72, page 

 143). Its lateral and ventral walls are supported by the hyoid 

 bone and the cartilages of the larynx. 



Craniad the pharynx continues, usually, without break into 

 the cavity lying dorsad of the soft palate. But at the time of 

 swallowing the free edge of the soft palate is pushed dorsad 

 against the dorsal wall of the pharynx, while the caudal part 

 of the pharynx is drawn craniad, so as to form a cavity con- 

 tinuous with that of the mouth. In this way the cavity above 

 the soft palate is completely separated at the time of swallow- 

 ing from the rest of the pharynx. This separated portion is 

 known as the nasopharynx : it is strictly a portion of the 

 respiratory passage, as the food does not pass into it. The 



