Fig. 40. Antrum of HIGHMORE with Roots of Teeth. 



The Alveolar Process and Teeth were ground off until the Antrum of Highmore 

 was well exposed; its Anterior wall was removed. 



The Incisor Teeth are in no relation with the Antrum. The Canine and 

 first Bicuspid Teeth are closely related to this cavity, but separated from it by a 

 thick layer of bone. The 2nd Bicuspid and tlie 3 Molar Teeth are in closer relation 

 to it. The roots of the Molars frequently project upwards as conical processes, 

 separated from it only by a thin layer of bone. Thus disease of the roots of the 

 last four teeth may lead to suppuration in the Antrum. On the other hand, an 

 empyaema of the Antrum of HiGHMORE may be drained by extracting one of the 

 teeth mentioned and perforating the thin layer of bone. 



Fig. 41. Frontal Sinuses. Nasal Ducts. 



Both Frontal Sinuses are chiselled open from the front. On the right, the 

 bones and sutures at the root of the nose are laid bare; on the left, the outer 

 wall of the Nose has been removed, as far as necessary to expose the duct which 

 leads from the Frontal Sinus to the Nasal Cavity. Mucous membrane is 



coloured pink. 



The Frontal Sinuses lie directly above the root of the nose, they entend 

 towards the forehead and over the orbital cavities from which they are separated 

 by the thin roof of the Orbit. Their greatest depth is above the nose; externally 

 they gradually become more flattened. Their size and shape vary enormously in 

 different people. Their utmost limits are laterally the fronto-malar suture and 

 superiorly half-way to the Summit of the vertical portion of the frontal bone. They 

 are separated from each other by a thin lamina of bone, which practically always 

 deviates from the middle line. 



They are to be considered as ethmoidal cells which have been pushed 

 into the frontal bone, in this way, the external table and diploe lie in front, and 

 the internal table behind them. This explains the strength of the anterior wall 

 and its resistance to external violence. 



Their inner siirface is irregular and may present recesses resembling diverti- 

 cula. They are, as their origin explains, lined by mucous membrane. 



They alwa3's communicate with the nasal cavity; the opening of this 

 communication lies invariably in the middle nasal meatus (infundibulum), into which 

 the Antrum of Highmore also opens (cf. Fig. 39). The Frontal Sinus may reach 

 as far as the anterior end of the Ethmoidal turbinated bone and open by means 

 of a simple slit, or the anterior ethmoidal cell may be very large and thus cause 

 constriction of the lower part of the Sinus; in this case a Canal is formed: — the 

 naso-frontal duct — . 



These deviations explain why it is very easy in some cases, and difficult 

 in others — or even impossible — to introduce a canula into the Frontal Sinus 

 through the nose. 



