1410 



HUMAN ANATOMY. 



from the limen to the cribriform plate of the ethmoid and roofed in by the forepart 

 of the arched upper boundary of the fossa, is long and narrow in consequence of 

 the approximation of the median and lateral walls. It leads from the nasal aperture 

 to the summit of the nasal fossa and to it Merkel applied the name carina nasi. 



The Nasal Septum. The median wall consists of the partition formed chiefly 

 by the perpendicular plate of the ethmoid, the vcmer and the septal cartilage, cov- 

 ered on both sides by mucous membrane. The extreme lower and anterior part of 

 the septum, consisting of the alar cartilage and the integument, is flexible, and there- 

 fore called the membranous portion, or septum mobile ; the terms bony and cartilagi- 

 nous portions are applied to the remaining parts of the septum supported by bone 

 and cartilage respectively. 



While during early childhood its position is median, in the great majority of 

 adults the septum presents more or less asymmetry and lateral deflection, most often 



FIG. 1174. 



Frontal sinus 



Superior turbinate 



Spheno-ethmoidal recess 



Opening of sphenoidal sinus 



Superior meatus 



Opening of 



Eustachian tube 



Vestibule 



Limen vestibuli 



\ 



Posterior limit of nasal fossa 

 Middle meatus 

 Middle turbinate 

 Inferior meatus 

 Right nasal fossa, lateral wall ; and naso-pharynx. 



to the right. This deviation may affect the septal cartilage alone, may be limited to 

 the bones (in 53 per cent, according to Zuckerkandl), or may be snared by both. 

 The most common seat of the deflection is the junction of the ethmoid and vomer, in 

 the vicinity of the spheno-ethmoidal process, or along the union of the vomer and 

 the septal cartilage. The asymmetry may involve the entire septum, which then is 

 oblique ; or it may take the form of a simple bulging towards one side, a double or 

 sigmoid projection ; or be an angular deflection resembling a fold, crest or spur that 

 projects into one, sometimes both, of the fossae (Heymann). 



Although the mucous membrane covering the nasal septum is generally smooth 

 and of fairly constant thickness, its surface is marked by inequalities caused chiefly 

 by variations in the amount and development of the glandular and vascular tissue. 

 One such accumulation, the tube re i< /inn s<-/>//\ is relatively constant and on the septum 

 about opposite the anterior end of the middle turbinate. During early life a series 

 of from four to six or more oblique ridges, plica septi, often model the lower and 

 posterior part of the septum, extending from below upward and forward. Slightly 

 above the anterior nasal spine, the septal mucosa presents the minute openings lead- 

 ing into the rudimentary organ of Jacobson. Behind, the margin of the bony septum 

 is covered by mucous membrane of unusual thickness which, therefore, forms the 

 immediate free edge of the partition separating the posterior nares. 



The Lateral Wall. The lateral wall of the nasal fossae is characteristically 

 modelled by the projecting scrolls (conchac nasi) of the three turbinates. The latter 

 partly subdivide each fossa into three lateral recesses, the superior, middle, and 



