72 BOXES OF THE HEAD. 



border, in front of the canine socket. The part in front of this fissure — namely, 

 that which bears the incisor teeth — forms in all mammals excei)t man a separate 

 bone, the iiiti-vinau-ilhinj or j>n:>iii{a'in<iri/ ; and anatomists have therefore sought 

 with great care for proofs of its original independence in the human subject, 

 but it does not appear that even in the earliest stages of development it has 

 been seen by any one entii-ely unattached to the rest of the bone, or that its line 

 of suture has been traced upon the facial surface. On the other hand, in cases 

 of completely cleft palate, the bones supporting the incisor teeth are placed on 

 a projecting portion of bone con-esponding to the premaxillai-y, which is articu- 

 lated to the fore part of the vomer, and is entnely detached from the superior 

 maxillaiy bones. 



The palate bone is ossified from a single centi'e, which appears in the seventh 

 or eighth week at the angle between its horizontal and ascending parts. 



The vom.er is ossified from a single nucleus appearing at the upper part about 

 the eighth week. From this nucleus two laminas are developed, which, passing dowTi 



Fig. G2. Fig. 62. — The F(etal Vomur near the time of IhuTii 



(R. Quaiu). 



1 & 2 show the two plates of which the bone consists, and 

 which are united behind and below. 



on either side of the middle line, embrace the septal car- 

 tilage. Tliese lamina3 gi-aduaUy undergo increased union 

 from behind forwards till the age of puberty, thus forming a mesial plate, ^vith. 

 only a groove remaining on its anterior and superior margins. 



The nasal and lachrymal bones are each ossified from a single centre, which 

 appears about the eighth week. 



The malar bone has been generally described as being ossified from a single 

 nucleus, but more recently it has been observed to be double in the human foBtus 

 of two months, and it remains composed of two parts in some quadrumana 

 through life. (Canestrini in Ann. d. Soc. d. Natur. in Modena, 18(37 ; Darwin, on 

 the Descent of Man, vol. i. p. 124.) 



The inferior turbinated bone is ossified from a single centre, which only 

 appears in the fifth month. 



The inferior maxilla begins to ossify before any other bone except the 

 clavicle. It consists of ;two similar lateral parts, which are still separate at birth. 



Fig. 63. Fig. 63. — The Inferior Maxilla of a 



Child at Birth (R. Qiiain). 



a kh indicate the two portions separate at 

 the symphysis. 



The ossific matter is at fii-st deposited 

 in fibrous tissue, siuTOunding the carti- 

 lage of Meckel externally, and at a later 

 period cartilage jiarticipates in the ossifi- 

 cation. Some observers admit only a 

 single ossific centre for each side (Nes- 

 bitt and Meckel) ; while, according to others, in addition to the main piece there 

 are separate nuclei for the coronoid process, the condyle, the angle, and the inner 

 side of the alveolus (Spix), or only for some of these parts (Kercki-ingius, 

 Beclard, Cniveilhier). The dental canal is at first a simple open groove ; but by 

 a gradually deepening, and by the gro-^iih of a thm lamina of bone upon the 

 inner side of the body of the jaw, it is converted into a channel at the bottom 

 of the dental groove. Tliis lamina also forms the inner wall of the dental groove, 

 in which, as in the upper jaw, the alveoli are formed by the subsequent gi-owth 

 of partitions. At birth the coronoid process is large, the neck of the condyle 

 short and bent backwai'ds, the ramus also veiy short and oblique, the angle at 



