54 



THE SKELETON 



palatine nerve from the ^:i)heno-i)alatine ganglion; lience it is sometimes called the 

 na--<o-p(d(itlnc (jroorc. 



The superior horder of the hone is expanded laterally into two aJiv. Tlie groove 

 Ix'tween them lodges the rostrum of the sphenoid, whilst the margin of each ala 

 eomes into contact with the sphenoidal process of the jjalate hone. Between the 

 al{e and the sphenoid a canal exists on each side of the rostrum for hlood-vessels. 

 The inferior horder is uneven, and is received into the groove formed hy the crests 

 of the opposed maxillae and the palatine bones of each side. The anterior border 

 joins posteriorly the mesethmoid, and in front the triangular (median) nasal 

 cartilage. The posterior l)order, smooth, rounded, and covered by mucous mem- 

 brane, serves to separate the posterior nares. The anterior and inferior borders 

 meet each other at the apex of the bone. 



Articulations. — Tlie vomer articulates with the sphenoid, palates, ethmoid, 

 and maxilhe, and with the triangular cartilage. 



ANTERIOR BORDER 



GROOVE FOR NASO-PALATINE NERVE 



GROOVE FOR SEPTAL CARTILAGE 



INFERIOR BORDER 



Fig. Go. — The Vomek. (Side view.) 



POSTERIOR BORDER 



Blood-supply. — Its arteries are derived from the anterior and posterior 

 ethmoidal, the naso-palatine, and the pterygo-palatine arteries, and twigs from the 

 posterior palatines through Stenson's canals. 



Ossification. — The vomer is a membrane-bone, and arises from a single centre 

 deposited in the lower border of the perichondrium of the ethmo-vomerine plate as 

 early as the eighth week. From this single centre a lamina of bone extends on 

 each side of the cartilage plate. For many weeks the vomer is a shallow bony 

 trough. Gradually it presses upon and induces alisorption of the enclosed cartil- 

 age, and 1)V degrees the laminge fuse, and form a rectangular plate of bone. At 

 birth the vomer presents an expanded lo^^"x?r border, especialh^ in cases of cleft 

 jtalate. 



THE XA.SAL 



These are two oblong bones situated in the middle line at the upper part of the 

 face, and forming the bridge of the nose. Each bone has two surfaces and four 

 liorders. The facial surface is concave from above down^vards, but convex from 

 side to side. Near its centre is a foramen for the transmission of a small tributarv 



Fio. fifi.— The Left Nasal P.oxe. 



SUPERIOR BORDER 



MEDIAN BORDER 

 OUTER BORDER 



INFERIOR BORDER 



MEDIAN BORDER 



GROOVE FOR NASAL NERVE 



to the facial vein. The posterior or nasal sunace is concave laterally, and 

 traversed l)y a longitudinal groove for the nasal branch of the ophthalmic nerve. 

 In life this surface has a covering of mucous membrane. The short sui)erior 

 l)order is tliick and serrated for articulation Avith the nasal notch of the frontal. 

 The inferior border is thin, and serves for the attachment of the lateral nasal 

 cartilages. Plach bone articulates with its fellow bv the median ])<)rder. wliicli is 



