t256 



A MANUAL OF ANATOMY 



The inner wall forms the septum nasi. 



The roof, which is narrow, is horizontal in its central part, the 

 anterior portion being sloped downwards and forwards, and the 

 posterior portion downwards and backwards. 



The floor is smooth, and at its anterior and inner part is the 

 incisor foramen, into which a funnel-shaped portion of the mucous 

 membrane extends. This region represents the wide communica- 

 tion which existed in early life between the nasal and buccal cavities. 



Each nasal fossa is divided into three regions — vestibular, ol- 

 factory, and respiratory. The vestibular region, or vestibule, forms 

 the anterior and lower part contiguous to the nostril. It is covered 

 by skin, which is provided with hairs or vibrissce. The olfactory 



Atrium 

 Orifice of Nasal Duct^ 



Vestibule 



Frontal Air-Sinus 



■ Infundibulum 



Opening of Anterior Ethmoidal Cells 

 j Cut Margin of Middle Concha 



\i' ,' j Hiatus Semilunaris 

 I / / Openuig of Middle Ethmoidal Cells 

 )S>Z / / / Bulla Ethmoidalis 

 V ' ' r'^^vte,^^'' , Spheno-ethmoidal Recess 

 .Superior Meatus 



Sphenoidal Air-Sinus 



Opening of Antrum of 

 Highmore 



— Eustachian Orifice 



Inferior Meatus I | 

 Middle Meatus • 

 Part of Inferior Concha g^^.^ p^,^^^ 



Fig. 514. — The Outer Wall of the Right Nasal Fossa. 



(The Superior and Middle Conchse and part of the Inferior Concha have 



been removed). 



region is situated superiorly, and corresponds to the superior concha 

 and the upper third of the septum nasi. The respiratory region 

 comprises the middle and inferior conchas, the middle and inferior 

 meatus, and the corresponding part of the septum. 



Mucous Membrane. — With the exception of the vestibule, which 

 is lined with skin, the nasal fossa is provided with a highly vascular 

 and sensitive mucous membrane, called the pituitary or Schnciderian 

 membrane. It is continuous through the posterior nares with 

 the mucous membrane of the naso-pharynx ; with that of the 

 nasal duct, lachrjonal sac, and lachrjonal canaliculi, and thence 

 with the conjunctiva ; and with that of the various air-sinuses 

 which communicate with the nasal fossa. It is thick and spongy 

 over the conchae, especially along the lower borders of the middle 



