NOSE. 



731 



the mucous membrane lining all the supple- 

 mental cavities, the nasal duct and lacrymal 

 sac, and the upper part of the pharynx. 



The course (as it is called) of the mucous 

 membrane next merits consideration. Ascend- 

 ing from the floor of the nasal fossa up the 

 outer side of the inferior meatus, it becomes 

 gradually thicker and more spongy. From this 

 meatus it is continued anteriorly into the nasal 

 duct, around whose lower orifice it forms an 

 annular fold or reduplication. The orifice in 

 the bones is elliptical and rather obliquely 

 placed, its anterior edge being somewhat lower 

 than the posterior. The fold of mucous mem- 

 brane around it is especially deep on the inner 

 side and posteriorly, and not only contracts 

 the size of the orifice, but acts as a valve to 

 guard it, and, when pressed upwards and for- 

 wards, to close it. Hence, though some per- 

 sons can inflate their lachrymal sacs, in most 

 men, when the nostrils are closed, and air is 

 pressed forcibly into the nose from behind, 

 none ever escapes from its cavities. 



As the lining membrane descends again upon 

 the outer surface of the inferior turbinated bone, 

 it becomes thicker, more spongy, and more vas- 

 cular. At the lower edge of the bone it 'forms 

 a deep fold, which, in its congested state, 

 touches the floor of the cavity. The fold is 

 peculiarly thick at the two ends of the bone, and 

 in disease in scrofulous children it sometimes 

 forms a loose and very vascular spongy mass, 

 which has been mistaken, it is said, for a poly- 

 pus. Immediately behind the deep posterior 

 fold the membrane becomes again thin and ad- 

 heres closely to the pterygoid plate of the 

 sphenoid bone, behind which, and on a level 

 with the extremity of the inferior turbinated 

 bone, it is continued into the orifice of the 

 Eustachian tube. 



As it passes from the inferior turbinated bone 

 to the outer wall of the middle meatus, the 

 Schneiderian membrane becomes again thinner 

 and more compact. About the middle of this 

 meatus it enters the deep channel of the infun- 

 dibulum, whose form it scarcely alters, and 

 along which it passes to the anterior ethmoidal 

 cells, and through them to the frontal sinuses. 

 Above the commencement of the infundibulum 

 it enters into the antrum by a narrow orifice 

 directed obliquely from before backwards. Of 

 the great opening into the antrum when the 

 superior maxillary bone is separated, a large 

 portion is covered by the palatine and turbi- 

 nated bones ; and of what remains, all but a 

 narrow circular orifice at the upper and anterior 

 part is closed by a thick annular fold of the 

 mucous membrane; and even permanent closure 

 is no rare consequence of the swelling to which 

 the membrane is subject. Cloquet* says that 

 this fold contains in man a gland with numer- 

 ous orifices analogous to one of large size which 

 surrounds the orifice of the antrum in many 

 animals. I have not been able to find such a 

 structure, and even E. II. Weberf has not been 

 more successful. 



* Osphresiologie, p. 247. 



f Hiltlcbrandt's Anatomic, Bd. iv. 



The membrane covering the middle turbi- 

 nated bone and the anterior portion of the cel- 

 lular part of the ethmoid is thick and spongy, 

 but less so than that on the inferior turbinated 

 bone. In the superior meatus it is thin ; and 

 it becomes still thinner as it passes into the 

 one or more orifices of the posterior ethmoidal 

 cells, on the borders of which it is tightly ap- 

 plied, and whose size, as it forms no loose pro- 

 jecting fold, it diminishes but little. It closes, 

 at this part, the spheno-palatine foramen, and 

 in the vault of the nasal fossce all the foramina 

 of the cribriform plate, through which nerves 

 and vessels are admitted to the outer surface of 

 the mucous membrane, and the inner surface 

 of the periosteum. At the lower borders of the 

 superior and middle turbinated bones it forms 

 thick folds, which make the meatus appear far 

 smaller than they do in the dry bones. These 

 folds are not so deep as that on the inferior tur- 

 binated bone ; but, as they probably receive 

 many filaments of the olfactory nerve, both they, 

 and perhaps the inferior fold also, may be 

 regarded as means for the multiplication of the 

 sensitive surface, and as analogous, in some 

 measure, to the folds of mucous membrane by 

 which alone in Fish and the Proteus anguinus 

 the same object is attained 



In all the rest of its extent over the septum, 

 the nasal bones, and the lateral cartilages, the 

 Schneiderian membrane has a uniform surface 

 and is of about middle thickness : its layers 

 are intimately united, and it adheres with mode- 

 rate firmness to the bone and cartilage. 



Nerves of the nose. The ol factory nerve, 

 or, as it may be more properly called, the 

 olfactory lobe of the brain, arises from the 

 posterior, inner, and inferior part of the an- 

 terior lobe of the cerebrum. It lies in the 

 groove between the two most internal of the 

 convolutions of this part of the brain, and may 

 be divided into three parts; the posterior, 

 or pyramid, the anterior, or bulb, and the 

 middle, or proper trunk of the nerve or lobe. 

 At its origin it may be traced backwards into 

 three roots. Of these, the outer or long root 

 appears first in the fissura Sylvii at the junction 

 of the anterior and middle lobes of the cerebrum, 

 just above the trunk of the middle cerebral 

 artery. Hence, its chief portion proceeds in- 

 wards, forwards, and a little downwards on the 

 under surface of the anterior lobe and in front 

 of the substantia perforata anticu ; and on 

 coming near the other roots it turns more 

 directly forwards and unites with them at the 

 beginning of the groove between the two convo- 

 lutions. In this course it receives on its outer 

 border one or more separate fasciculi, which 

 come from the deeper part of the lobe and are 

 sometimes completely concealed by grey mat- 

 ter covering them. 



The inner or short root is first visible at the 

 inner and posterior part of the anterior lobe of 

 the cerebrum, in front of the beginning of the 

 fissura Sylvii, and just outside the great me- 

 dian division of the cerebrum. It consists of 

 one or more fasciculi, and passes outwards and 

 forwards to the commencement of the groove, 

 where, curving round like the preceding, but 



