34 



ANATOMY AND PHYSIOLOGY 



orbital plate of the maxilla in the floor. The lacrimal and ethmoid bones are 

 in the medial wall; the sphenoid and zygomatic bones in the lateral wall. 



The lacrimal canal begins in the lacrimal bone and runs down 

 into the nose. The optic foramen, for the optic nerve, is at the 

 apex of the fossa. 



Nasal fossa. Roof formed by nasal and ethmoid bones; floor 

 by maxillary and palate bones; lateral watt by nasal, ethmoid, 



FIG. 26. THE BONY SEPTUM. 

 Body of sphenoid immediately be- 

 hind it. (Morris.) 



FIG. 27. HYOID BONE, ANTERIOR 



ASPECT. 



i, i, Anterior or convex surface of 

 body; 2, 2, greater cornua; 3, 3, junc- 

 tion of greater cornua with body; 4, 

 lesser cornua. (Sappey.) 



maxillary, and palate bones; septum by ethmoid and vomer 

 (Fig. 26). 



The openings on the face, or anterior nares, are bounded by the 

 maxillary and nasal bones, and separated by the vomer. The 

 openings into the throat or posterior nares are bounded by the 

 sphenoid and palate bones, and separated by the vomer. Turbi- 

 nated bones are seen on the lateral walls of the fossae. 



Each nasal fossa communicates with four sinuses: the sphenoid, ethmoid, 

 frontal, and maxillary. The sphenoid sinus opens into the upper and back 

 part; the ethmoid, frontal, and maxillary (or antrum of Highmore) open at the 

 side, lower down. The lacrimal canal also opens at the side near the floor. 



The nasal fossae are lined with mucous membrane (the 

 Schneiderian membrane) which is continued into all of the sinuses 

 and the pharynx. 



Clinical note. Inflammation of this membrane may extend 



