802 



THE ORGANS OF SENSE. 



Nares 



Crus laterale A of greater 

 Crus mediate f alai L. 



Lower edge of 

 cartilage of 

 septum 



Fatty tissue of 

 ala nasi 



FIG. 671. CARTILAGES OF NOSE FROM BELOW. 



expanded area, the vestibule ; this is bounded laterally by the lateral crus of the 

 greater alar cartilage, and medially by the lower part of the septum; it is prolonged 

 as a small recess towards the apex of the nose. The vestibule is partly subdivided 



by a curved ridge. It is lined with skin and, 

 in its lower half, there are hairs and sebace- 

 ailtl . ous glands; the hairs are curved downwards 

 j cartilage to g uarc [ the entrance to the nostril. The 

 superior part of the vestibule is smooth, 

 and is limited above and posteriorly by a 

 slightly marked arched prominence, the 

 limen nasi, beyond which the nasal cavity 

 is lined with mucous membrane. 



Each nasal cavity, above and behind 

 the vestibule, is divided into a superior or 

 olfactory, and an inferior or respiratory 

 region. The olfactory region is a narrow 

 slit-like space; it comprises the middle of the superior nasal concha and the 

 corresponding portion of the septum. The respiratory region includes the remaining 

 part of the cavity. 



Septum Nasi (Fig. 668). Where the bony septum of the nose is deficient, below 

 and in front, the gap is filled by the septal cartilage. Until the seventh year the 

 nasal septum lies, as a rule, in the median plane, but after this age it is very often 

 bent to one or other side more frequently to the right the deflection being greatest 

 usually along the line of junction of the vomer with the perpendicular lamina of 

 the ethmoid. De- 

 flection of the 

 septum is more 

 common in Euro- 

 pean than in non- 

 European skulls 

 occurring in 

 about 53 per cent 

 of the former and 

 in about 28 per 

 cent of the latter 

 (Zuckerkandl). 

 Associated with, 

 or apart from, this 

 deviation, crests 

 or spurs of bone 

 are found, project- 

 ing from the sep- 

 tum into one or 

 other nasal cavity, 

 in about 20 per 

 cent of skulls. In 

 the septum, a little 

 above and in front 

 of the naso-pala- 

 tine recess, is a 

 minute orifice, not 



always recognisable, from which a blind pouch extends upwards and backwards for 

 a distance of from 2 to 9 mm. This is the vomero-nasal organ of Jacobson, and is 

 supported by the vomero-nasal cartilage. In man this organ is rudimentary, but 

 in many of the lower animals it is well developed (Fig. 673), and probably plays 

 a part in the sense of smell, since it is lined with epithelium similar to that 

 covering the olfactory region, and is supplied by branches of the olfactory nerve. 



Lateral Wall (Fig. 674). In the lateral wall of the nasal cavity,above the superior 

 nasal concha, is a narrow recess, the recessus sphenoethmoidalis, into the posterior 



Inferior 

 concha' 



Maxillary 

 sinus 



Inferior 

 meatus 



FIG. 672. FRONTAL "SECTION THROUGH NASAL CAVITIES 

 SECTION VIEWED FROM BEHIND. 



ANTERIOR HALF OF 



