82 



THE SKELETON 



The cribriform plate is pierced, on each side, by numerous foramina, arranged in two or 

 three rows, which transmit the filaments of the olfactory nerves descending from the bulb. 

 Those in the middle of the groove are few and are simple perforations, through which pass the 

 nerves to the roof of the nose; the medial and lateral series are more numerous and constitute 

 the upper ends of small canals, which subdivide as they course downward to the upper parts 

 of the septum and the lateral wall of the nasal fossa. At the front part of the cribriform plate 

 is a narrow longitudinal slit, on each side of the crista galli, which transmits the anterior eth- 

 moidal (nasal) branch of the ophthalmic division of the fifth nerve. The posterior border 

 articulates with the ethmoidal spine of the sphenoid. 



Fig. 102. 



-Section through the Nasal Fossa to show the Mesethmoid 

 (Lamina Perpendicularis). 



Crest of sphenoid^-^ 



Groove for naso-palatine aerve ^J^Ui' . 



Crest of palate bone 

 Spine of palate bone 



Frontal spine 



Crest of maxilla 



The perpendicular plate (mesethmoid) [lamina perpendicularis is directly 

 continuous with the crista galli on the under aspect of the cribriform plate, so 

 that the two plates cross each other at right angles. The larger part of the 

 perpendicular plate is below the point of intersection and forms the upper third 

 of the septum of the nose. It is quadrangular in form with unequal sides. 



Fig. 103. — The Ethmoid. 



(Lateral view.) 

 — Crista galli 



interior ethmoidal groove 



ji?osterior ethmoidal groove 

 Lamina papyracea 



Uncinate process 



Inferior nasal concha 



Sphenoidal concha 

 Middle nasal concha 



Tlio anterior l)ord»!r articulates with the spine of the frontal and the crest of the nasal bones. 

 The inferior border articulates in front with the septal cartilage of the nose and behind with the 

 anterior margin of the vom(!r. The posterior margin is very thin and articulates with the crest 

 of thcsplienoid. This plate, which is generally deflected a little to one side, presents above a 

 number of grooves and minute canals which lead from the inner set of foramina in the cribri- 

 form plate and transmit the olfactory nerves to the septum. 



The labyrinth (lateral mass) is oblong in shape and suspended from the under 

 aspect of the lateral part of the cribriform plate. It consists of two scroll-like 



