THE PALATE BONE 109 



angle of junction of the sphenoidal and maxillary portions a short, rounded, non- 

 articular margin is generally seen; this forms the anterior boundary of the spheno- 

 maxillary fissure; occasionally no such nonarticular margin exists, the fissure 

 being completed by the direct junction of the maxilla and sphenoid bones or by 

 the interposition of a small Wormian bone in the angular interval between them. 

 On the super o-internal surface of the orbital process are seen a single or double tem- 

 poromalar foramen (foramen zygomaticoorbitale) , the entrance of the temporomalar 

 canal. This canal may be bifurcated, or there may be two canals from the begin- 

 ning; one of these usually opens on the posterior surface, the other (occasionally 

 two) on the facial surface; they transmit filaments (temporomalar) of the orbital 

 branch of the superior maxillary nerve. 



The zygomatic process (processus temporalis), long, narrow, and serrated, artic- 

 ulates with the zygomatic process of the temporal bone. 



Borders. The antero-superior (orbital border} is smooth, arched, and forms 

 a considerable part of the circumference of the orbit. The antero-inferior or 

 maxillary border is rough, and bevelled at the expense of its inner table, to articu- 

 late with the maxilla, affording attachment by its margin to the Levator labii 

 superioris proprius, just at its point of junction with the maxilla. The postero- 

 superior (temporal border) curved like an italic letter /, is continuous above with 

 the commencement of the temporal ridge; below, with the upper border of the 

 zygomatic arch; it affords attachment to the temporal fascia. The postero-inferior 

 (masseteric border) is continuous with the lower border of the zygomatic arch, 

 affording attachment by its rough edge to the Masseter muscle. 



Development. The malar bone ossifies generally from three centres, which appear about the 

 eighth week one for the zygomatic and two for the orbital portion and which fuse about the 

 fifth month of fetal life. The bone is sometimes, after birth, seen to be divided by a horizontal 

 suture into an upper and larger and a lower and smaller division. In some primates the malar 

 bone consists of two parts, an orbital and a malar. 



Articulations. \Yith four bones three of the cranium, frontal, sphenoid, and temporal; and 

 one of the face, the maxilla. 



Attachment of Muscles. To four the Levator labii superioris proprius, Zygomaticus 

 major and minor, and Masseter. 



The Palate Bone (Os Palatinum). 



The palatal bones 1 are situated at the back part of the nasal fossae ; they are wedged 

 in between the maxilla and the pterygoid processes of the sphenoid (Fig. 78). 

 Each bone assists in the formation of three cavities the floor and outer wall of the 

 nose, the roof of the mouth, and the floor of the orbit and enters into the formation 

 of two fossae, the sphenomaxillary (fossa pterygopalatina) and pterygoid fossae 

 (fossa pterygoidea)] and one fissure, the sphenomaxillary fissure (fissura orbitalis 

 inferior). In form the palate bone somewhat resembles the letter L, and may be 

 divided into an inferior or horizontal plate and a superior or vertical plate. 



The Horizontal Plate (pars horizontalis) (Figs. 79 and 80) is of a quadrilateral 

 form, and presents two surfaces and four borders. 



Surfaces. The superior or nasal surface (fades uasalis), concave from side to 

 side, forms the back part of the floor of the nasal cavity. 



The inferior or palatine surface (fades palatina), slightly concave and rough, forms 

 the back part of the hard palate. At its posterior part may be seen a transverse 

 ridge, more or less marked, for the attachment of part of the aponeurosis of the 



1 The word palate is frequently used as an adjective. Palatal is the correct form (from palatum, the palate), 

 but usage sanctions palatine in certain compounds, despite the fact that palatine is derived from palatium, a 

 palace. This is another example of what is charitably called a ' 'late Latin" form, akin to hallur and hallucis. 

 [EDITOR.] 



