THE MAXILLARY BONES. 27 



their relation to the antrum, to be presently described ; in 

 the zygomatic surface, which is convex and forms part of 

 the zygomatic fossa, are several orifices transmitting the 

 posterior dental nerves and vessels ; a groove which, con- 

 nected by the apposition of the palate bone into a canal, 

 forms the posterior palatine canal ; and at the bottom, a 

 rounded eminence, the maxillary tuberosity, which lies 

 behind the wisdom tooth, and has been occasionally broken 

 off in extracting that tooth. 



The body of the bone is excavated by an air-chamber, the 

 antrum, which is coated in life by a continuation of the nasal 

 mucous membrane, and this frequently becomes secondarily 

 involved in dental disease, so that its anatomical relations 

 are of great importance to the dentist. 



Like the somewhat similar air cavities in the frontal bone 

 the maxillary sinus does not attain to its full size, relatively 

 to the rest of the bone, until after the age of puberty, 

 although it makes its appearance earlier than the other 

 nasal sinuses, its presence being demonstrable about the 

 fifth month of foetal life. Hence it follows that its walls are 

 thicker in the young subject than in the adult; and, ac- 

 cording to the observations of Mr. Cattlin (*), it is somewhat 

 larger in the male than in the female. 



It is very variable in size, so that out of one hundred 

 adult specimens the above-mentioned writer found one 

 which would only contain one drachm of fluid, while in 

 contrast with that was another which held eight drachms ; 

 two and a half drachms being the average capacity. Al- 

 though it is exceedingly variable in form as well as in size, 

 it tends towards a roughly pyramidal shape, the apex of the 

 pyramid being directed towards the malar bone, which it 

 has been seen to encroach upon, and the base towards the 

 nasal cavity; it is, however, useless to minutely describe 



(*) "Transactions of the Odontological Society," vol. ii. 1857. 



