THE NASAL CAVITY 



513 



chondrium. It is continuous in front with the slvin which lines the nostrils, and 

 behind with the mucous membrane of the pharjaix. It is also continuous at the 

 naso-maxillary opening with the very thin and much less vascular mucous mem- 

 brane which lines the paranasal sinuses. In the anterior part of the cavity it forms 

 prominent thick folds on the lateral wall, which ext(>nd from the turbinate bones to 

 the nostril. There are usually two dorsal turbinate folds which unite anteriorly. 



Dorsal meatus 



Septum nasi Lacrimal sac 



Transverse 

 facial vessels 



Palatine artery 



Vena reflexa 

 Palatine vein 

 Buccinator and 

 Dep. lahii inf. 

 Buccinator 



vessels and 



nerve 



Lingual nerve 

 Lingual artery 

 Lingual vein 



Mandibular 

 duct 



Hypoglossal 

 nerve 



Digastricus (ant. belly) 



External 



maxillary 



vessels 



Pariitiil duct 



Fig. 456. — Cross-section of Head of Hohse. The Section Passes Thkough the Medial Canthi and is Viewed 



FROM Behind. 



i, Mylo-hyoideus; jS, stylo-glossus; 5, hyo-glossus; .^, genio-glossus; 5, lingual process of hyoid bone. An arrow 

 points to the naso-maxillary opening. The projecting edge just above the arrow point is the anterior margin of the 

 fronto-maxillary opening. 



The upper one encloses a thin plate of cartilage which is continuous with the dorsal 

 turbinate bone. The ventral turbinate fold is curved, and encloses an '"N,^ shaped 

 cartilaginous plate which prolongs the ventral turbinate bone; this fold is con- 

 tinuous with the alar fold of the nostril, and forms with it the upper margin of the 

 entrance from the nostril to the nasal cavity. Below this there is a rounded ridge 

 produced by the nasal process of the premaxilla. The mucous membrane of the 

 33 



