THE HEAD AND NECK. 117 



dental canals, containing vessels and nerves for the teeth. (Fig. 51.) On the 

 outer surface of this wall is the infraorbital plexus of nerves, formed by the 

 infraorbital branches of the fifth and seventh nerves. Entrance to the antrum for 

 purpose of drainage is gained by going through this wall too. 



5. Posterior ivall. On this you will find the posterior dental canals for 

 nerves and vessels to the posterior teeth of the superior maxilla. (Fig. 5 I.) The 

 apex of the antrum corresponds to the prominence of the cheek. 



W hat can you say of the size of the antrum of Highmore, or maxillary sinus ? 



It will contain about one ounce of fluid. It is variable in size in different 

 persons. It is longer in the male than in the female. A large bone may have a 

 very small antrum, and vice versa. 



IV hat can you say of the floor of the ai/tniui / 



The floor is the strongest wall. It is uneven on account of the roots of the 

 teeth, the first and second molars being usually those producing the uneven- 

 ness. These tooth-roots may even penetrate the floor of the antrum, and be the 

 exciting cause of disease of the antral mucous membrane. The antrum may be 

 divided into several compartments, or pockets, as they are called, by bony par- 

 titions of variable thickness and height, a circumstance which must always enter 



INFRAORBITAL FORAMEN 



NASAL NOTCH 



CANINE FOSSA 



NASAL SPINE 



INCISIVE FOSSA 



CANINE EMINENCE 



BORDER OF SPHENO-MAX1LLARY 



FISSURE 

 FOR SPHENOID 



ZYGOMATIC SURFACE 

 MALAR PROCESS 

 POSTERIOR DENTAL CANALS 



TUBEROSITY 



FIG. 79. THE l.v.vv MAXILLA. (Outer view.) 



as a prognostic factor in operations to establish drainage on the antrum. The 

 surgeon should ask himself after each operation, " Have I drained the antrum or 

 only a pocket of the antrum ? " A merchant had a wine-cellar flooded with water. 

 He employed a company to remove the water. A hose was thrust through a 

 dark window and the pump started. To the dismay of the merchant, the experts 

 had thrust the hose into a hogshead of wine, and drained the pocket, instead of 

 the cellar. 



What cany 'ou say of the nerve -supply of the antrum ? 



The nerve-supply of the mucous membrane of the antrum comes from the 

 anterior and posterior superior dental branches of the fifth nerve. You will 

 remember this : The dental nerves supply the teeth ; the skin of the lips and 

 cheeks covering these teeth outside ; the gums surrounding these teeth, through 

 small branches called the nervuli gingivales ; and, lastly, the mucous membrane 

 of the antrum. 



Describe the blood-supply of the antrnin f 



The internal maxillary artery gives off branches not only to the teeth (dental 

 branches), but also branches to the gums (gingival branches), and antral branches 

 to the mucous membrane of the antrum. These antral branches are accom- 

 panied by sympathetic nerves. 



