THE NASAL CAVITY 



83 



behind, and the vomer below. In the fresh state it is completed by the cartilage 

 ot the septum nasi (Cartilago septi nasi). 



Fig. 55. — Cross-section of Nasal Region of .Skull 

 OF Horse; the Section Passes Through the 

 Anterior End op the Facial Chest, and Be- 

 tween THE Third and Fourth Cheek Teeth. 

 a, Dorsal, 6, ventral, turbinate bone ; c, d, cavities 

 of a and 6; e, common meatus; /, g, h, dorsal, middle, 

 ventral meatus; i, k, passages to cavities of turbinate 

 bones; I, naso-lacrimal duct; m, infraorbital canal; n, 

 anterior end of maxillary sinus; o, septal cartilage. 

 (After Ellenberger, in Leisering's Atlas.) 



Fig. 56. — Cross-section of Nasal Region of Skull 

 OF Horse; the Section is Cut About Half- 

 way between the Orbit and the Anterior 

 End op the Facial Chest, and P.isses be- 

 tween the Fipth and Sixth Cheek Teeth. 

 a. Dorsal, 6, ventral, turbinate bone; c, d, cavities 

 of a and b: e, common meatus; /, dorsal, g, middle, k, 

 ventral meatus; i, placed over ridge in maxillary sinus; 

 k, communication between outer and inner (turbinate) 

 part of maxillary sinus; I, naso-maxillary opening; m, 

 naso-lacrimal canal; n, infraorbital canal. (After 

 Ellenberger, in Leisering's .\tlas.) 



The turbinate bones divide each half of the nasal cavity into three meatus 



nasi. 



The dorsal meatus (Meatus nasi dorsalis) is a narrow passage between the 

 roof and the dorsal turbinate bone. It ends at the cribriform plate of the ethmoid. 



Fig. 57. — Skull op Young Horse; Lateral View, with Sinuses Opened Up. 

 A', A, Anterior and posterior compartments of maxillary sinus; B, B' , frontal and turbinate parts of frontal sinus, 

 C, orbit; 1, septum between compartments of maxillary sinus; 2, 2, infraorbital canal; 3, turbinate part of maxillary 

 sinus; 4, 5, 6, last three cheek teeth (covered by thin plate of bone) ; 7, anterior limit of maxillary sinus in older subject; 

 8, infraorbital foramen; 9, anterior end of facial crest; 10, course of naso-lacrimal duct; 11, fossa for lacrimal sac; 12, 

 dorsal turbinate bone; 13, fronto-maxillary opening. 



The middle meatus (Meatus nasi medius) is the space between the two turbinate 

 bones. In its posterior part is the very narrow opening into the maxillary sinus. 

 The ventral meatus (Meatus nasi ventralis) is the channel along the floor which is 



