THE NASAL FOSS^. 



141 1 



inferior meatuses. These are overhung by the corresponding bony concha, the 

 superior meatus being roofed in by the upper turbinate and the inferior lying between 

 the lower turbinate and the floor of the fossa. That part of the nasal fossa between 

 the conchse and the septum, into which the recesses open medially, is sometimes called 

 the meatus nasi communis. The details of the nasal fossa as seen within the macerated 

 skull have been described in connection with the skeleton (page 223). In the recent 

 condition, when the soft parts are in place, while their general contour is preserved, 

 the compartments of the fossae are materially reduced in size by the thickness of the 

 mucous membrane and the erectile tissue that cover the bony framework. 



The Superior Meatus. — Corresponding to the small size of the upper turbinate, 

 the superior meatus (meatus nasi superior), or ethmoidal fissure, is narrow and 

 groove-like and little more than half the length of the middle one. It is directed 

 downward and backward and is floored by the convex upper surface of the middle 

 concha. When the upper turbinate is replaced by two scrolls (conchae superior 

 et suprema) — a condition that Zuckerkandl regards as very frequent, if indeed, not 

 the more usual — the meatus is accordingly doubled. Into the upper and front part 

 of the superior meatus the posterior ethmoidal air-cells open by one or more orihces 



Fig. 1175. 



Frontal sinus 

 Probe in infundibulum 



Middle turbinate, partly 

 removed 



Hiatus semilunaris 

 Ethmoidal bulla jL. 



Openings Agger nasi 



of maxillary sinus 

 into infundibulum 

 Ventriclt 



Limen nasi 



Vestibule 



Probe in naso-lachrymal 

 duct 



Opening of middle ethmoidal cells 



Superior turbinate, partly removed 



Opening into spheno-elhmoidal recess 



Sphenoidal sinus 



Opening of posterior 

 ethmoid cells into 

 superior meatus 



1 Naso-pharynx 



Opening of Eustach- 

 ian tube 



Inferior meatus 



Inferior turbinate, 

 partly removed 



Middle meatus 



Lateral wall of nasal fossa ; portions of turbinate bones have been removed to expose 



openings into air spaces. 



of variable size. Above and behind the upper turbinate and in front of «the body of 

 the sphenoid bone lies a diverticulum, the spheno-ethmoidal recess, into the posterior 

 part of which opens the sphenoidal sinus. 



The Middle Meatus. — The recess beneath the middle turbinate (meatus nasi 

 medius) is spacious and arched to conform with the contour of the middle and 

 inferior conchae which constitute its roof and fioor respectively. On elevating, 

 or still better removing close to its attachment, the middle turbinate bone, a deep 

 crescentic groove, the i7ifundibulum , is seen on the outer wall of the fossa overhung 

 by the anterior half of the concha. The crescentic cleft leading from the middle 

 meatus into the infundibulum is the hiatus semilunaris,^ which extends from above 

 downward and backward, with its convexity directed forward. Its anterior boundary 

 is a sharp crescentic ridge due to the uncinate process of the ethmoid covered 

 with thin mucous membrane, while behind it is limited by a conspicuous elevation 

 produced by the corresponding underlying bony projection of the ethmoidal bulla. 



^ Some confusion exists in the use of this term, since it is often applied to the entire groove and 

 not merely to the cleft which leads from the meatus into the groove. The name is here employed 

 as indicating the lunate cleft and not the groove (which is the infundibulum), as originally used 

 by Zuckerkandl, who introduced it. See Antomie der Nasenhohle, VVien, 1882, page 39. 



