194 



MUSCLES OF THE SOFT PALATE. 



Fig. in.* superior and middle constrictor muscles, and 



spreads out beneath the mucous membrane 

 of the pharynx, its inferior fibres being in- 



4serted into the posterior border of the thyroid 

 - cartilage. 

 * L Relations. By its external surface with 



the stylo-glossus muscle, external carotid 

 artery, parotid gland, and the middle con- 

 strictor. By its internal surface with the 

 internal carotid artery, internal jugular vein, 

 superior constrictor, palato-pharyngeus, and 

 mucous membrane. Along its lower border 

 is seen the glosso-pharyngeal nerve which 

 crosses it, opposite the root of the tongue, to 

 pass between the superior and middle con- 

 strictor and behind the hyo-glossus. 



The palato-pharyngeus is described with 

 the muscles of the soft palate. It arises from 

 the soft palate, and is inserted into the inner surface of the pharynx, and 

 posterior border of the thyroid cartilage. 



Actions. The three constrictor muscles are important agents in deglu- 

 tition ; they contract upon the morsel of food as soon as it is received by 

 the pharynx, and convey it downwards into the esophagus. The stylo- 

 pharyngei draw the pharynx upwards and widen it laterally. The palato- 

 pharyngei also draw it upwards, and with the aid of the uvula close the 

 opening of the fauces. 



Sixth Group. 'Muscles of the Soft Palate. 



Levator palati, 

 Tensor palati, 

 Azygos uvulae, 

 Palato-glossus, 

 Palato-pharyngeus. 



Dissection. To examine these muscles, the pharynx must be opened 

 from behind, and the mucous membrane carefully removed from off the 

 posterior surface of the soft palate. 



The LEVATOR PALATI, a moderately thick muscle, arises from the ex- 

 tremity of the petrous bone and from the posterior and inferior aspect of 

 the Eustachian tube, and passing down by the side of the posterior nares 

 spreads out in the structure of the soft palate as far as the middle line. 



Relations. Externally with the tensor palati and superior constrictor 

 muscle ; internally and posteriorly with the mucous membrane of the 

 pharynx and soft palate ; and by its lower border with the palato-pha- 

 ryngeus. 



* A side view of the muscles of the pharynx. 1. The trachea. 2. The cncoid car- 

 lihvge. 3. The crico-thyroid membrane. 4. The thyroid cartilage. 5. The thyro-hyoi- 

 <lean membrane. 6. The os hyoides. 7. The stylo-hyoidean ligament. 8. The oeso- 

 phagus. 9. The inferior constrictor. 10. The middle constrictor. 11. The superior 

 constrictor. 12. The stylo-pharyngeus muscle passing down between the superior and 

 middle constrictor. 13. The upper concave border of the superior constrictor; at this 

 point the muscular fibres of the pharynx are deficient. 14. The pterygo-rnaxil'ary liga- 

 ment. 15. The buccinator muscle. 16. The orbicularis oris. 17. The mylo-hyoideus. 



