150 



TOPOGRAPHICAL ANATOMY OF THE 



of this meatus that the maxillary sinus opens by a narrow, slit-like 

 orifice. The inferior meatus (meatus nasi inferior) is placed between 

 the inferior concha and the floor of the nose, is the widest of the nasal 

 passages, and forms a direct line of communication between the nostril 

 and the pharynx. The three passages are put into continuity by the 

 cornmon meatus (meatus nasi communis), a cleft-like channel between 

 the turbinated bones and the nasal septum. 



The most anterior part of the lateral wall of the nasal cavity carries 

 elongated prominences or folds of mucous membrane. The most dorsal 

 of these is continuous with the anterior end of the upper turbinated 

 bone, and, on beiuo- traced backwards, will be found to beoin as two 



Nasal septum. 



Diverticulum nasi 

 A. lateralis nasi. 



A. labialis superior. 

 Naso-lachrymal duct. 



M. orbicularis oris. 



A. dorsalis nasi. 



Ramus nasalis externus. 

 .M. levator labii superioris proprius. 



Alar fold. 



M. dilator naris inferior. 

 . Ramus nasalis anterior. 



M. caninus. 

 Ramus labialis sui)erior 



Vomero-nasal organ. 



Fig. 65. — Transverse section of the nose at the level indicated by 

 F in Fig. 1 (looking forward). 



rounded ridges that soon become confluent. The upper of the two 

 ridges usually contains a small cartilaginous prolongation of the 

 turbinated bone. A second fold is appended to the inferior turbinated 

 bone, and, from its connection with the ala of the nostril, is dis- 

 tinguished as the alar fold (plica alaris). It is in this fold that the 

 curved cartilaginous continuation of the lower turbinated bone is con- 

 tained. A third ridge of mucous membrane lies still more ventral, and 

 is produced by a thick venous plexus that extends backwards on to the 

 lower turbinated bone. In it is to be found the naso-lachrymal duct 

 (ductus nasolacrimalis), by which the tears reach the nostril. 



NcLSo-palatine Duct and Vomero- Nasal Organ. — If search be made 

 on the floor of the nose opposite the palatine fissure, a small, slit-like 

 opening should be found. A probe introduced into the opening enters 



