THE NASAL CAVITY 



439 



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

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

 cealed l)y the overhanging superior turbinal. A fine flexible probe, joassed 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 tneatus 



Septum nasi 



Lacrimal sac 



Digastricus {ant. hdli/) 



Exicriuil 



maxillary 

 vessels 



Parttl/d duct 



Transverse 

 facial vessels 



Palatine artery 



Vena reflexa 

 I 'alatine vein 

 Buccinator and 



l)('p. lahii inf. 

 Buccinator 



vessels and 



nerve 



Lingual nerve 

 Lingual artery 

 Lingual vein 



Submaxillary 

 luct 

 Hypoglossal 



nerve 



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

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



points to the naso-maxillary fis.sure. 



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 turl)inals 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 



