80 INFERIOR TURB1NATED BONES VOMER. 



horizontal with the perpendicular portion of the bone. It is received into 

 the angular fissure, which exists between the two plates of the pterygoid 

 process at their inferior extremity, and presents three surfaces : one con- 

 cave and smooth, which forms part of the pterygoid fossa ; and one at 

 each side to articulate with the pterygoid plates. The anterior face of 

 this process is rough, and articulates with the superior maxillary bone. 



Development. By a single centre, which appears in the angle of union 

 between the horizontal and perpendicular portion, at the same time with 

 ossification in the vertebrae. 



Articulations. With six bones : two of the cranium, the sphenoid and 

 ethmoid ; and four of the face, the superior maxillary, inferior turbinated 

 bone, vomer, and the palate bone of the opposite side. 



Attachment of muscles. To four : the tensor palati, azygos uvulae, 

 internal and external pterygoid. 



INFERIOR TURBINATED BONES. The inferior turbinated or spongy bone, 

 is a thin layer of light and porous bone, attached to the crista turbinalis 

 inferior of the inner wall of the nares, and projecting inwards towards 

 the septum narium. The inferior turbinated bone is broad in front, nar- 

 row and tapering behind, and slightly curled upon itself, so as to bear 

 some resemblance to one valve of a bivalve shell, hence its designation 

 concha inferior. The bone presents for examination a convex and a con- 

 cave surface, and a superior and an inferior border. The convex surface 

 looks inwards and upwards, and forms the inferior boundary of the middle 

 meatus naris ; it is marked by several longitudinal grooves for branches 

 of the spheno-palatine nerve and artery. The concave surface looks down- 

 wards and outwards, and constitutes the roof of the inferior meatus. The 

 superior border is irregular ; it is attached to the crista turbinalis inferioi 

 of the superior maxillary bone in front, to the same crest on the palate 

 bone behind, and between those attachments gives off two, and sometimes 

 three, thin and laminated processes. The most anterior of these processes, 

 processus lachrymalis, articulates with the lachrymal bone, and assists in 

 completing the nasal duct. The middle process, processus maxillaris, 

 descends and assists in closing the antrum maxillare ; while the posterior, 

 processus ethmoidalis, \vhich is often wanting, ascends towards the eth- 

 moid bone, and also takes part in the closure of the antrum maxillare. 

 The inferior border is rounded, and thicker than the rest of the bone. 



Development. By a single centre, which appears at about the middle 

 of the first year. 



It affords no attachment to muscles. 



Articulations. With four bones : the ethmoid, superior maxillary, la- 

 chrymal, and palate. 



VOMER. The vomer is a thin, quadrilateral, plate of bone, forming the 

 posterior and inferior part of the septum of the nares. 



The superior border is broad and expanded, to articulate, in the middle, 

 with the under surface of the body of the sphenoid, and on each side with 

 the processus vaginalis of the pterygoid process. The anterior part of this 

 border is hollow r ed into a sheath for the reception of the rostrum of the 

 sphenoid. The inferior border : s thin and irregular, and is received into 

 the grooved summit of the crista nasalis. The posterior border is sharp 

 and free, and forms the posterior division of the two nares. The anterior 



