VOMER. 49 



hence its designation concha inferior. The bone presents for examina- 

 tion a convex and concave surface, and a superior and inferior border. 

 The convex surface looks inwards and upward, and forms the inferior 

 boundary of the middle meatus naris ; it is marked by several longi- 

 tudinal grooves for branches of the sphenopalatine nerve and artery. 

 The concave surface looks downwards and outwards, and constitutes 

 the roof of the inferior meatus. The superior border is irregular ; it 

 is attached to the crista turbinalis inferior of the superior maxillary 

 bone in front, to the same crest on the palate bone behind, and be- 

 tween 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 com- 

 pleting the nasal duct. The middle process, processus maxillaris, de- 

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

 processus ethmoidalis, which is often wanting, ascends towards the 

 ethmoid bone, and also takes part in the closure of the antrum maxil- 

 lare. 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, 

 lachrymal, 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 hollowed into a sheath for the reception 

 of the rostrum of the sphenoid. The inferior border is thin and 

 irregular, and is received into the grooved summit of the crista nasalis. 

 Tiie posterior border is sharp and free and forms the posterior division 

 of the two nares. The anterior border is more or less deeply grooved 

 for the reception of the central lamella of the ethmoid and cartilage of 

 the septum. This groove is an indication of the early constitution of 

 the bone of two lamella?, united at the inferior border. The vomer not 

 unfrequently presents a convexity to one or the other side, generally 

 it is said, to the left. 



Development. By a single centre, which makes its appearance at 

 the same time with those of the vertebrae. Ossification begins from 

 below and proceeds upwards. At birth the vomer presents the form 

 of a trough in the concavity of which the cartilage of the septum nasi 

 is placed ; it is this disposition which subsequently enables the bone 

 to embrace the rostrum of the sphenoid. 



The vomer has no muscles attached to it. 



Articulations. With six bones ; the sphenoid, ethmoid, two superior 

 maxillary, and two palate bones, and with the cartilage of the septum. 



