THE NASAL CAVITY 



997 



of the nose; the sphenopalatine branch of the internal maxillary, which supplies the mucous 

 membrane covering the conchas, the meatuses and septum; the septal branch of the superior labial 

 of the external maxillary; the infraorbital and alveolar branches of the internal maxillary, which 

 supply the lining membrane of the maxillary sinus; and the pharyngeal branch of the same artery, 

 distributed to the sphenoidal sinus. The ramifications of these vessels form a close plexiform 

 net-work, beneath and in the substance of the mucous membrane. 



Epitheliu 



Nerve bundles 



FIG. 857. Section of the olfactory mucoua membrane. (Cadiat.) 



The veins form a close cavernous plexus beneath the mucous membrane. This plexus is especi- 

 ally well-marked over the lower part of the septum and over the middle and inferior conchae. Some 

 of the veins open into the sphenopalatine vein; others join the anterior facial vein; some accom- 

 pany the ethmoidal arteries, and end in the 

 ophthalmic veins; and, lastly, a few communi- 

 cate with the veins on the orbital surface of the 

 frontal lobe of the brain, through the foramina 

 in the cribriform plate of the ethmoid bone; 

 when the foramen cecum is patent it transmits 

 a vein to the superior sagittal sinus. 



The lymphatics have already been described 

 (p. 695). 



The nerves of ordinary sensation are: the 

 nasociliary branch of the ophthalmic, filaments 

 from the anterior alveolar branch of the max- 

 illary, the nerve of the pterygoid canal, the 

 nasopalatine, the anterior palatine, and nasal 

 branches of the sphenopalatine ganglion. 



The nasociliary branch of the ophthalmic 

 distributes filaments to the forepart of the 

 septum and lateral wall of the nasal cavity. 

 Filaments from the anterior alveolar nerve 

 supply the inferior meat us and inferior concha. 

 The nerve of the pterygoid canal supplies the 

 upper and back part of the septum, and superior' 

 concha; and the upper nasal branches from the sphenopalatine ganglion have a similar distri- 

 bution. The nasopalatine nerve supplies the middle of the septum. The anterior palatine 

 nerve supplies the lower nasal branches to the middle and inferior conchae. 



The olfactory, the special nerve of the sense of smell, is distributed to the olfactory region. 

 Its fibers arise from the bipolar olfactory cells and are destitute of medullary sheaths. They 

 unite in fasciculi which form a plexus beneath the mucous membrane and then ascend in grooves 

 or canals in the ethmoid bone; they pass into the skull through the foramina in the cribriform 

 plate of the ethmoid and enter the under surface of the olfactory bulb, in which they ramify 

 and form synapses with the dendrites of the mitral cells (Fig. 772). 



FIG. 858. Nerves of septum of nose. Right side 



