THE INFERIOR NASAL CONCHA 169 



from the orbital surface by a rounded border, which enters into the formation of 

 the inferior orbital fissure. 



The Sphenoidal Process (processus sphenoidalis] . The sphenoidal process is 

 a thin, compressed plate, much smaller than the orbital, and directed upward 

 arid mediahvard. It presents three surfaces and two borders. The superior surface 

 articulates with the root of the pterygoid process and the under surface of the 

 sphenoidal concha, its medial border reaching as far as the ala of the vomer; it 

 presents a groove which contributes to the formation of the pharyngeal canal. 

 The medial surface is concave, and forms part of the lateral wall of the nasal cavity. 

 The lateral surface is divided into an articular and a non-articular portion: the 

 former is rough, for articulation with the medial pterygoid plate; the latter is 

 smooth, and forms part of the pterygopalatine fossa. The anterior border forms 

 the posterior boundary of the sphenopalatine notch. The posterior border, ser- 

 rated at the expense of the outer table, articulates with the medial pterygoid 

 plate. 



The orbital and sphenoidal processes are separated from one another by the 

 sphenopalatine notch. Sometimes the two processes are united above, and form 

 between them a complete foramen (Fig. 168), or the notch may be crossed by one 

 or more spicules of bone, giving rise to two or more foramina. 



Ossification. The palatine bone is ossified in membrane from a single center, which makes 

 its appearance about the sixth or eighth week of fetal life at the angle of junction of the two parts 

 o:' the bone. From this point ossification spreads medialward to the horizontal part, downward 

 into the pyramidal process, and upward into the vertical part. Some authorities describe the 

 bone as ossifying from four centers: one for the pyramidal process and portion of the vertical 

 part behind the pterygopalatine groove; a second for the rest of the vertical and the horizontal 

 parts; a third for the orbital, and a fourth for the sphenoidal process. At the time of birth the 

 height of the vertical part is about equal to the transverse width of the horizontal part, whereas 

 in the adult the former measures about twice as much as the latter. 



Articulations. The palatine articulates with six bones: the sphenoid, ethmoid, maxilla, 

 inferior nasal concha, vomer, and opposite palatine. 



The Inferior Nasal Concha (Concha Nasalis Inferior; Inferior Turbinated Bone). 



The inferior nasal concha extends horizontally along the lateral wall of the 

 lasal cavity (Fig. 170) and consists of a lamina of spongy bone, curled upon itself 

 ike a scroll. It has two surfaces, two borders, and two extremities. 



The medial surface (Fig. 171) is convex, perforated by numerous apertures, 

 jid traversed by longitudinal grooves for the lodgement of vessels. The lateral 

 urface is concave (Fig. 172), and forms part of the inferior meatus. Its upper 

 >order is thin, irregular, and connected to various bones along the lateral wall 

 >f the nasal cavity. It may be divided into three portions: of these, the anterior 

 irticulates with the conchal crest of the maxilla; the posterior with the conchal 

 :rest of the palatine; the middle portion presents three well-marked processes, 

 vhich vary much in their size and form. Of these, the anterior or lacrimal process 

 s small and pointed and is situated at the junction of the anterior fourth with 

 i he posterior three-fourths of the bone : it articulates, by its apex, with the descend- 

 ing process of the lacrimal bone, and, by its margins, with the groove on the back 

 of the frontal process of the maxilla, and thus assists in forming the canal for the 

 nasolacrimal duct. Behind this process a broad, thin plate, the ethmoidal process, 

 ascends to join the uncinate process of the ethmoid; from its lower border a thin 

 lamina, the maxillary process, curves downward and lateralward; it articulates 

 with the maxilla and forms a part of the medial wall of the maxillary sinus. The 

 inferior border is free, thick, and cellular in structure, more especially in the middle 

 of the bone. Both extremities are more or less pointed, the posterior being the 



ore tapering. 





