THE NASAL CAVITY 



439 



maxillary sinus communicates with the nasal cavity — the naso-maxillary fissure 

 (Aditus naso-maxillaris). The fissure is not visible from the nasal side, being con- 

 cealed by the overhanging superior turbinal. A fine flexible probe, passed outward 

 and somewhat backward between the turbinal bones, enters the maxillary sinus; if in- 

 troduced a little further in the same direction, it usually passes through the orifice 

 of communication between the maxillary and the frontal sinus and enters the latter. 



Superior meatus 



Septum nasi 



Lacrimal sac 



Transverse 

 facial vessels 



Palatine artery 



]'ena reflexa 

 Palatine vein 

 Buccinator and 

 Dcp. laini inf. 

 Buccinator 



vessels and 



nerve 



Lingual nerve 

 Lingual artery 

 Lingual vein 



Sub?naxillary 



/ duct 

 ^ — . u 



Hypoglossal 



nerve 



Digastricus {ant. belly) 



External 



maxillary 



vessels 



Parotid duct 



Fig. 348. — Cross-section of Head of Horse. The Section P.\sses Through the Internal Canthi. 

 7, Mylo-hyoideus; 3, stylo-glossus; S, hyo-glossus; 4, genio-glossus; 5, lingual process of hyoid bone. An arrow 



points to the naso-ma.xillary fissure. 



A small part of the fissure usually brings the anterior division of the maxillary 

 sinus into communication with the nasal cavity. The spaces inclosed by the coiled 

 portions of the turbinals also open into the middle meatus. This passage may 

 be characterized as the sinus-meatus, but it also conducts air to the olfactory 

 region. 



The inferior meatus (Meatus nasi ventralis) is situated between the inferior 



