1426 HUMAN ANATOMY. 



bones and the mucous membrane of the meatuses, including the lower part of the 

 olfactory region, and in addition send twigs to the ethmoidal cells and the frontal 

 and maxillary sinuses. The naso-palatine artery supplies the septum and upper part 

 of the olfactory region. Numerous smaller, and for the most part collateral, twigs 

 derived from the anterior and posterior ethmoidal branches of the ophthalmic pass to 

 the upper part of the fossa; from the descending palatine, branches are distributed 

 to the posterior part; and from the lateral nasal and septal, branches from the facial 

 twigs supply the nostril. In addition to those from the posterior nasal, the antrum 

 receives branches from the infraorbital. The sphenoidal sinus is supplied chiefly 

 by the pterygo-palatine artery. The ultimate distribution is effected by capillary 

 net-works which supply the periosteum, the glands and the tunica propria. 



The veins returning the blood from the rich venous plexuses and the cavernous 

 tissue within the nasal mucous membrane follow three chief paths passing (a) forward 

 to the facial vein, (^) backward to the spheno-palatine, and (/■) upward into the 

 ethmoidal veins. The latter communicate with the ophthalmic vein and the veins 

 and superior sagittal sinus within the dura mater. A communication of greater 

 importance, however, is established by a vein that accompanies the anterior ethmoidal 

 artery through the cribriform plate into the anterior central fossa and empties either 

 into the venous plexus of the olfactory tract or into one of the larger veins on the 

 orbital surface of the frontal lobe (Zuckerkandl). 



The lyvtphatics within the mucous membrane are represented by an irregular 

 plexus of lymph-vessels in addition to perineural lymph-sheaths surrounding the 

 olfactory nerve-bundles. Both sets may be filled by injection from the subarachnoid 

 space. The larger lymphatics pass backward toward the posterior nares and join 

 two trunks, one of which is continued to the prevertebral node and the other to the 

 hyoid nodes. According to Schief^erdecker, the basal canals (page 951 j communi- 

 cate with the lymphatics and probably facilitate the escape of fluid which aids the 

 glands in keeping moist the epithelium lining the nasal fossae. 



The nerves include the special olfactory fibres concerned in the sense of smell, 

 and those of common sensation derived from the ophthalmic and superior maxillary 

 divisions of the trigeminal ner\'e. The lateral wall of the nasal fossa is supplied from 

 several sources, including the upper posterior nasal branches from Meckel's ganglion 

 and the lower posterior nasal branches from the larger palatine nerve behind, and, 

 in front, the external division of the nasal nerve and the nasal branch of the anterior 

 superior dental, which also distributes twigs to the floor of the fossa. The septum 

 receives its chief supply from the naso-palatine nerve, supplemented by branches 

 from Meckel's ganglion behind and by the internal division of the nasal nerve 

 in front. The mucous membrane lining the antrum receives filaments from the 

 infraorbital nerve by means of its superior dental branches. The frontal sinus is 

 supplied by twigs from the supraorbital and the nasal nerves ; the ethmoidal air-cells 

 by minute branches from the nasal, and the sphenoidal sinus by filaments from the 

 spheno-palatine ganglion. 



PRACTICAL CONSIDERATIONS : THE ACCESSORY AIR-SPACES. 



Trauma of the accessory sinuses — with the exception of the maxillary antrum, 

 which may be in\olved in extensive (crushing) fractures of the face — usually takes 

 the form of perforating wounds, commonly from falls on sharp objects. The 

 thinness of their walls, and the ease with which they may be traversed by such a 

 vulnerating body, are well illustrated by a case in which a fall forward on to the tip 

 of an umbrella resulted in a wound which began on the face above the bicuspid 

 teeth, passed through the maxillary sinus, the sphenoidal sinus, and entered the 

 cranium, the ferrule of the umbrella being found embedded in the pons (Treves). 



Inflammation of the accessory sinuses is not infrequent, on account of the con- 

 stant exposure of the nasal mucosa to atmospheric sources of infection. It has a 

 tendency to become chronic because (a) the openings of the sinuses are small and — 

 with the exception of the frontal — are badly placed for drainage ; {b) the ciliated 

 epithelium, on the activity of which the removal of the sinus contents depends, is apt 

 to be so damaged by the primary inflammation that retention of secretion occurs ; 

 (<:) the mucosa around the different ostia is so loosely attached that it readily 



