

THE FACE, MOUTH AND PHARYNX 195 



to one or other side. It may be caused by excessive growth of 

 the vomer and the perpendicular plate of the ethmoid, and 

 the septum buckles along the line of their articulation. Over- 

 growth of the septal cartilage alone is obstructed posteriorly 

 by the osseous septum, in which its margins are firmly fixed. In 

 this case, too, deviation occurs, but only the cartilaginous part 

 of the septum is affected. Deviation of the septum may result 

 from trauma, and it tends to occlude the nasal fossa into which 

 it projects. 



Fracture of the nasal bone occurs about half an inch above its 

 lower margin and usually leads to lateral displacement of the 

 nose ; but if, in addition, the perpendicular plate of the ethmoid 

 is broken, the nose is depressed backwards. These fractures 

 are usually compound through the mucous membrane, and 

 surgical emphysema is apt to follow if the patient blows his 

 nose. Owing to the plentiful blood-supply of the parts, rapid 

 union occurs, and it is therefore important that the fragments 

 should be replaced as soon as possible after the accident. 



The Maxillary Sinus (Antrum of Highmore) appears during 

 the third month of foetal life as a budding-out from the mucous 

 membrane of the nasal cavity in the region of the middle meatus. 

 It grows into the maxillary process, and the maxillary bone is 

 formed around it. 



The maxillary sinus is roughly pyramidal in shape. Its 

 apex is situated at the zygomatic (malar) process, and its base 

 forms the lateral wall of the nasal cavity. Above, it is roofed 

 in by the orbital surface of the maxilla, which is channelled by 

 the infra-orbital nerve. The postero-lateral wall of the sinus 

 forms one of the boundaries of the infia-temporal (zygomatic) 

 fossa, and its antero-lateral wall is depressed externally to form 

 the canine fossa. Inferiorly, the sinus is bounded by the alveolar 

 border, and the roots of the molar and premolar teeth form 

 projections in its floor. The walls are lined by muco-periosteum, 

 which is continuous with the mucous membrane of the middle 

 meatus of the nose through the opening of the sinus, which is 

 placed in the upper part of its medial wall. 



Infection may reach the maxillary sinus directly from the 

 middle meatus, or it may ascend through the floor from carious 

 teeth. When pus is present in the sinus, the natural method 

 of drainage into the middle meatus is far from efficient, as the 

 sinus can only be emptied completely when the head is bent over 

 to the opposite side. When the patient lies down, the pus 



