ANTERIOR ASPECT OF HEAD AND NECK. 



(limen nasi). The inner wall (septum) is both bony and carti- 

 laginous and often deflected. On it, just above and in front of 

 a depression (recessus nasopalatinus) on the floor, over the in- 

 cisive foramen, is an orifice whence a blind pouch (organ of 

 Jacobson) runs upward and backward. [719] 



Outer Wall. The sphenoidal sinus opens into a recess 

 (spheno-ethmoidal) above the superior turbinated bone. The 

 superior meatus is under cover of the superior turbinated 

 bone ; the posterior ethmoidal cells open into it in front. The 

 middle meatus, lying under and external to the middle tur- 

 binated bone, presents an elevation (bulla ethmoidalis) into, 

 or above, which the middle ethmoidal cells open; below and 

 in front of the bulla is a deep groove (hiatus semilunaris) into 

 which the anterior ethmoidal cells and antrum of Highmore 

 open. The middle meatus is continuous antero-superiorly with 

 the infundibulum, and anteriorly with a depressed area 

 (atrium) lying just above the vestibule and limited above and 

 in front by a ridge (agger nasi) . The inferior meatus lies below 

 the inferior turbinated bone and presents anteriorly the orifice 

 of the nasal duct. [720] 



The olfactory nerves lie at first in grooves on the inner and 

 outer walls of the olfactory area, the region of the superior 

 turbinated bone and the corresponding part of the sep- 

 tum; they then pass in the mucosa to the olfactory cells. 



[723] 



THE EXTERNAL EAR. 



Pinna, or Auricle. Outer surface: Near its centre is a de- 

 pression (concha) ; a ridge (crus helicis) divides this into upper 

 (cymba conchse) and lower (cavum conchse) parts; the latter 

 opens into the meatus. Anteriorly the crus helicis is contin- 

 uous with the margin (helix) of the pinna, which is folded over, 

 curves over the top of the pinna, and is lost just below its 

 middle behind. Posteriorly a ridge (antihelix) ascends in 

 front of the helix, a furrow (scapha) separating them, and bi- 



[95] 



