950 



THE ORGAXS OF DIGESTfOX 



outwards to the apex of the petrous portion of tlie trniporal lionc, and thenee to 

 the Eustachian tuhe and internal pterygoid plate. 



It descends alone:; the ptervgo-maxillary ligament to the posterior of the 

 mylo-hyoid ridge of the lower jaw and jiasses thence along the side of the tongue 

 to the hyoid 1)on(' and larynx. 



The mucous membrane of the pliarynx is continuous with the several cavities 

 which ojx-n into it. It is closely adherent to the base of the skull, thick and spongy 

 and dark in colour. It l)econies thinner where it approaches the openings of the 

 posterior nares and Eustachian tul»cs, and Ix'low it is ])al(r and folded longitudi- 



FiG. 559a. — The Muscles of the Pharynx. 



INTERNAL PTERYGO PLATE 

 Superior eoustrietor 



Pteryg o-raandibular 

 ligament 

 Stylo-hyoid ligament — 



Stylo-pharyngeus 



Inferior constrictor 



Crieo-thyroid 

 Cricoid cartilage 



nally. Lynii)hoid follicles and numerous racemose glands exist throughout the 

 mucous membrane. 



The epithelium is ciliated and columnar in the naso-pharynx, but becomes 

 stratified and scaly in the lower portion. 



Muscles. — The muscular coat consists of the three constrictor muscles, 

 witli additional librcs dcrivc<l from the stylo- and palato-pharyngei muscles. 



The inferior constrictor is tliick and strong. It arises from the thyroid carti- 

 lage immediately bcliiiul the r»l)li(jue line and superior tubercle, and also from the 

 inferior cornu and the side of the cricoid cartilage, behind the crico-thyroid muscle 

 (fig. 524). The fibres spread backwards and inw\irds, the lowest horizontally, 

 whilst those above ascend more and more obliquely, and are inserted into the 



