BONES OF THE FACE. 127 
At birth the ossified lateral masses are united to the central cartilaginous plate by a 
fibrous layer. Two centres make their appearance in the mesial cartilage on either side 
of the root of the crista galli about the end of the first year; from these, the crista galli 
and the vertical plate are ossified as well as the mesial part of the cribriform plate, the 
lateral portions of which are derived from an inward extension of the lateral mass. 
Ossification is usually complete about the fifth or sixth year. About the twenty-fifth 
year bony union has taken place between the cribriform plate and the sphenoid, but 
ankylosis between the vertical plate and the vomer is not usual till the fortieth or forty- 
fifth year. 
WormMIAN Bones. 
Along the line of the cranial sutures and in the region of the fontanelles, isolated 
bones of irregular form and variable size are oceasionally met with. These are the 
so-called Wormian bones, named after the Danish anatomist Wormius. They are also 
ealled sutural or epactal bones. Their presence depends on the fact that they are 
either developed from distinct ossific nuclei, or it may be from a division of the primary 
ossific deposit. They usually include the whole thickness of the cranial wall, or it may 
be only involve the outer or inner tables of the cranial bones. They are most frequent in 
the region of the lambda and the lambdoid suture. They occur commonly about the 
pterion, and in this situation are called epipteric bones (Flower). By their fusion with 
one or other of the adjacent bones they here lead to the occurrence of a fronto-squamosal 
suture. Their presence has also been noted along the line of the sagittal suture, and 
sometimes in metopic skulls in the inter-frontal suture. They are occasionally met with 
at the asterion and more rarely at the obelion. They appear less frequently in the face, 
but their presence has been noted around the lachrymal bone, and also at the extremity of 
the spheno-maxillary fissure, where they may form an independent nodule wedged in 
between the great wing of the sphenoid, the malar, and the superior maxillary bones. 
BONES OF THE FACE. 
The bones of the face (ossa faciei), fourteen in number, comprise two superior 
maxille, two palates, two malars, two lachrymals, and two nasals, together with the 
vomer and inferior maxilla. 
THE SUPERIOR MAXILLARY BONES. 
The superior maxille (maxille), of which there are two, unite to form the 
upper jaw. Each consists of a body, with which are connected four projections, 
named respectively the zygomatic, frontal, alveolar, and palatal processes. 
The body (corpus) is of pyramidal form, and contains within it a hollow called 
the antrum or maxillary air sinus. It has four surfaces—an antero-external or facial, 
a postero-external or zygomatic, a supero-external or orbital, and an internal or 
nasal. The antero-eaternal or facial surface (facies anterior) is confluent below with 
the alveolar process. Above, it is separated from the orbital aspect by the 
infraorbital margin (margo infraorbitalis), whilst internally it is limited by the free 
margin of the nasal notch, which ends below in the pointed anterior nasal spine 
(spina nasalis anterior). Posteriorly it is separated from the zygomatic surface by 
the inferior border of the zygomatic process. The facial aspect of the bone is ridged 
by the sockets of the teeth (juga alveolaria). The ridge corresponding to the root 
of the canine tooth is usually the most pronounced; and internal to this, and over- 
lying the roots of the incisor teeth, is the shallow incisive or myrtiform fossa, whilst 
placed externally, on a higher level, is the deeper canine fossa, the floor of which 
is formed in part by the projecting zygomatic process. Above this, and near the 
infraorbital margin, is the infraorbital foramen, the external opening of the 
infraorbital canal, which transmits the infraorbital nerve and artery. The postero- 
external or zygomatic surface is separated above from the orbital aspect by a 
‘rounded free edge, which forms the anterior margin of the spheno-maxillary fissure 
in the articulated skull. Inferiorly, and in front, it is separated from the facial 
surface by the zygomatic process and its free lower border. Internally it is limited 
by a sharp irregular margin with which the palate bone articulates. This surface 
