122 OSTEOLOGY. 
area (facies temporalis), concavo-convex from before backwards. It slopes inwards 
below, where it is separated from the zygomatic area by a well-marked muscular 
ridge, ‘the infra- temporal crest or pterygoid ridge (crista infratemporalis). Behind, 
the temporal surface is bounded by the margin of the great wing which articulates 
with the squamous temporal, and above by the edge which unites it with the 
anterior inferior angle of the parietal and the frontal bone. The temporal surface 
enters into the formation of the floor of the fossa of the same name, and affords an 
extensive attachment to the fibres of origin of the temporal muscle. The zygomatic 
surface (facies infratemporalis), situated below the infra-temporal crest, corresponds 
to the under surface of the posterior half of the great wing; 1t extends as far back 
as the alar spine and posterior border. Opening on it are seen the orifices of the 
foramen spinosum and ovale. It is shghtly concave from side to side, and is 
confluent internally with the outer surface of the external pterygoid plate. In 
front it is bounded by a ridge which curves upwards and outwards from the fore 
part of the external pterygoid plate to joi the infratemporal crest. In the 
articulated skull this ridge forms the posterior boundary of the pterygo-maxillary 
fissure. The zygomatic surface overhangs the zygomatic fossa, and atfords origin 
to the upper head of the external pterygoid muscle. 
The pterygoid processes (processus pterygoidel) spring from the [inferior 
surface of the lateral aspect of the body as well as the under side of the root of 
the great wings, and pass vertically downwards. Hach consists of two lamine, the 
external and internal pterygoid plates, fused together anteriorly, and enclosing 
between them posteriorly the pterygoid fossa (fossa pterygoidea). The external 
pterygoid plate (lamina lateralis processus pterygoidei), thin and expanded, is 
directed obliquely backwards and outwards, its lower part being often somewhat 
everted. Its hinder edge is sharp, and often has projecting from it one or two 
spines, to one of which (processus pterygo- spinosus) the pterygo-spinous lgament 
which stretches towards the alar spine is attached. Externally it furnishes an 
origin for the lower head of the external pterygoid muscle, and on its inner side, 
where it forms the lateral wall of the pterygoid fossa, it supplies an attachment for 
the internal pterygoid muscle. 
The internal pterygoid plate (lamina medialis processus pterygoidei) 1s narrower 
and somewhat stouter. By its inner aspect it forms the posterior part of the 
lateral wall of the nasal fosse; externally it is directed towards the pterygoid 
fossa. Its posterior edge ends below in the hook-like hamular process (hamulus 
pterygoidei), which, reaching a lower level than the external plate, curves back- 
wards and outwards, furnishing a groove in which the tendon of the tensor palati 
muscle glides; superiorly, the sharp posterior margin of the inner plate bifurcates, 
so as to enclose the shallow scaphoid fossa from which the tensor palati muscle 
arises, and wherein may occasionally be seen the inferior aperture of the foramen 
Vesalii. To the inner edge of this fossa, as well as to the posterior border of the 
internal pterygoid plate, the pharyngeal aponeurosis is attached. Here, too, the 
cartilage of the Eustachian tube is supported on a shght projection, and the palato- 
pharyngeus muscle receives an origin, whilst the superior constrictor of the pharynx 
arises from the lower third of the same border and from the hamular process. 
Superiorly and internally the inner plate forms an incurved lamina of bone, the 
vaginal process (processus vaginalis), which is applied to the under surface of the 
lateral aspect of the body reaching inwards, towards the root of the rostrum, from 
which, however, it is separated by a groove, in which, in the articulated skull, the 
ala of the vomer is lodged. The angle formed by the vaginal process and the 
internal edge of the scaphoid fossa forms a projection called the pterygoid tubercle, 
immediately above which is the posterior aperture of the Vidian canal (canalis 
pterygoideus), through which the Vidian nerve and artery are transmitted. On its 
under surface the vaginal process displays a groove (sulcus pterygo- -palatinus) 
which in the ar bioulated skull is converted fa, the pterygo-palatine canal by its 
union with the palate bone. In front, at its root, the pterygoid process displays a 
broad smooth surface (facies spheno- maxillaris), which is confluent above with the 
root of the great wing around the foramen rotundum, and forms the posterior wall 
of the spheno- maxillar y fossa. Here, to the inner side of the foramen rotundum, 
