THE PALATE BONES. 37 
consists of a horizontal and a vertical plate, united to each other like the limbs of 
the letter L. At their point of union there is an irregular outstanding process, 
called the tuberosity, whilst capping the summit of the vertical plate and separated 
by a deep cleft are two irregular pieces of bone, called the sphenoidal and orbital 
processes. 
The horizontal plate (pars horizontalis) has two surfaces and four borders. 
As its name implies, it is horizontal in position, and forms the posterior third of 
Sphenoid Orbital process hi 
Sp ( tal process Orbital process 
~Ethmoid 
COE Orbital surface . 
sS Yi Orbital surface b 
SEES, -Orbital sur f 
y Wit We, Ethmoid ey UB 
Sphenoidal |_ 4 
process eae 
Ethmoidal crest 
ae 
Eicioaccielia “aid 
notch |}; 
Wet 
Spheno- 
§ Sphenoid 
maxillary fossa *I 
Sphenoidal 
~Z process 
For superior maxilla “Superior 
meatus 
Spheno-palatine noteh— 
Middle meatus 
Inferior 
>>,/Antral surface turbinated 
3 crest 
For internal _\ 
pterygoid plate 
Maxillar Inferior meatus 
process 
Maxillary 
Pterygoid fossa / 
4 process 
‘or external 
pterygoid 
plate ( 
, Pterygoid fossa 
ashe 
i Vac 9} ——— ‘em Mi) Ee 
Tuberosity Nasal crest 5p Tuberosity 
i : Horizontal ae 
urface for ac Surfs eteniGn ating { 
poe eae Shae Eqaverior ge an Ne pa plate Posterior Internal 
pterygoideus for superior nasal spine pterygoid plate 
externus maxilla 
A B 
Fic. 108.—RicgHT PALATE BONE. 
A, As seen from the Outer Side ; B, As viewed from the Inner Side. 
the hard palate. Its upper surface, which is smooth, is slightly concave from side 
to side, and forms the floor of the hinder part of the nasal fosse. Its anferror 
surface, rougher, is directed towards the mouth, and near its posterior edge often 
displays a transverse ridge for the attachment of a part of the aponeurosis of the 
tensor palati muscle. The anterior border articulates by means of an irregular 
suture with the hinder edge of the palatal process of the superior maxilla. The 
posterior margin is free and concave from side to side; by its sharp edge it furnishes 
attachment to the aponeurosis of the soft palate. The internal border is upturned, 
and when it articulates with its fellow of 
the opposite side it forms superiorly a 
central crest continuous in front with the Sphenoid__ Oxbital 
nasal crest of the superior maxilla; it surface 
supports the hinder part of the lower — spnenoidal process 
Orbital process 
Spheno- 
mnaxillary 
border of the vomer, and projecting be- Ptsryeq Gabune IPS” fossa 
yond the line of the posterior border forms i 7 ive Splenorpals 
the posterior nasal or palatine spine Middle meatus-—- | 1 
9 si : { Posterior palatine 
(spina nasalis posterior). The external 7 canal 
border fuses with the vertical plate, form- Inferior turbinated 
ing with it a right angle. The hinder Hela 
: : : nferior meatus 
extremity of this edge is grooved by the Nasal erest 
lower end of the posterior palatine canal. For external 
pterygoid 
The vertical plate (pars perpen- eke plate 
dicularis) is very much broader below spine \ 
than above. Composed of thin bone, it is Horvontalplate — MLL 
liable to be broken in the process of dis- For internal pterygoid plate fossa 
articulation, particularly at its upper 
part, so that 1t is somewhat uncommon to 
meet with a perfect specimen. It may be As seen from Behind. 
described as possessing two surfaces and 
four borders. Its inner surface, which is directed towards the cavity of the nose, 
is crossed horizontally about its middle by the inferior turbinated crest (crista 
Fic. 109.—RicHt PALATE BONE. 
Vertical plate 
