STYLO-PHARYNGEUS. 



167 



Fig. 73* 



rior constrictor muscle; on the outer side by the internal pterygoid 

 muscle; and behind by the rectus anticus major and vertebral 

 column. In this space are situated the internal carotid artery, the 

 internal jugular vein, and the glosso-pharyngeal, pneumogastric, 

 spinal accessory, and hypoglossal nerve. 



Relations. By its external surface with the vertebral column and 

 its muscles, behind; with the vessels and nerves contained in the 

 maxillo-pkaryngeal space laterally, the middle constrictor, stylo- 

 pharyngeus, and tensor palati muscle. By its internal surface with 

 the levator palati, palato-pharyngeus, tonsil, and mucous membrane 

 of the pharynx, the pharyngeal fascia being interposed. 



The stylo-pharyngeus is a long and 

 slender muscle arising from the inner 

 side of the base of the styloid process : 

 it descends between the superior and 

 middle constrictor muscles, and spreads 

 out beneath the mucous membrane of 

 the pharynx, its inferior fibres being 

 inserted into the posterior border of the 

 thyroid cartilage. 



Relations. By its external surface 

 with the stylo-glossus muscle, external 

 carotid artery, parotid gland, and the 

 middle constrictor. By its internal 

 surface with the internal carotid artery, 

 internal jugular vein, superior constric- 

 tor, palato-pharyngeus, and mucous 

 membrane. Along its lower border is 

 seen the glosso-pharyngeal'nerve which 

 crosses it, opposite the root of the tongue. 



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 carti- 

 lage. 



Actions. The three constrictor muscles contract upon the morsel 

 of food as soon as it is received by the pharynx, and convey it 

 gradually downwards into the ossophagus. The stylo-pharyngei 

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

 pharyngei also draw it upwards, and narrow the opening of the 

 fauces. 



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

 tilage. 3. The crico-thyroid membrane. 4. The thyroid cartilage. 5. The thyro- 

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

 oesophagus. 9. The inferior constrictor. 10. The middle constrictor. 11. The supe- 

 rior 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-maxillary 

 ligament. 15. The buccinator muscle. 16. The orbicularis oris. 17. The mylo- 

 hyoideus. 



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