168 



THE SKELETON. 



form, concave, smooth, and forming the back part of the floor of the orbit, and 

 the external or zygomatic surface, directed outwards, backwards, and down- 

 wards, of an oblong form, smooth, lying in the spheno-maxillary fossa, and 

 looking into the zygomatic fossa. The latter surface is separated from the 

 orbital by a smooth rounded border, which enters into the formation of the 

 spheno-maxillary fissure. 



The Sphenoidal Process of the palate bone is a thin compressed plate, much 

 smaller than the orbital, and directed upwards and inwards. It presents three 

 surfaces and two borders. The superior surface, the smallest of the three, 

 articulates with the horizontal part of the sphenoidal turbinated bone ; it pre- 

 sents a groove which contributes to the formation of the pterygo-palatine canal. 

 The internal surface is concave, and forms part of the outer wall of the nasal 

 fossa. The external surface is divided into an articular and a non-articular 

 portion ; the former is rough for articulation with the inner surface of the 

 Dterygoid process of the sphenoid; the latter is smooth, and forms part of the 

 zygomatic fossa. The anterior border forms the posterior boundary of the 

 spheno-palatine foramen. The posterior border, serrated at the expense of the 

 outer table, articulates with the inner surface of the pterygoid process. 



The orbital and sphenoidal processes are separated from one another by a 

 deep notch, which is converted into a foramen, the spheno-palatine, by articu- 

 lation with the sphenoidal turbinated bone. Sometimes the two processes are 

 united above, and form between them a complete foramen, or the notch is 

 crossed by one or more spicula? of bone, so as to form two or more foramina. 

 In the articulated skull this foramen opens into the back part of the outer wall 

 of the superior meatus, and transmits the spheno-palatine vessels and nerves. 



Development. From a single centre, which makes its appearance at the angle 

 of junction of the two plates of the bone. From this point ossification spreads 

 inwards to the horizontal plate, downwards into the tuberosity, and upwards 

 into the vertical plate. In the foetus, the horizontal plate is much longer than 

 the vertical ; and even after it is fully ossified, the whole bone is at first re- 

 markable for its shortness. 



Articulations. With six bones ; the sphenoid, ethmoid, superior maxillary, 

 inferior turbinated, vomer, and opposite palate. 



Attachment of Muscles. The Tensor Palati, Azygos Uvula3, Internal and Ex- 

 ternal Pterygoid. 



THE INFERIOR TURBINATED BONES. 



The Inferior Turbinated Bones are situated one on each side of the outer 

 wall of the nasal fossae. Each consists of a layer of thin spongy bone, curled 

 upon itself like a scroll, hence its name "turbinated;" and extends horizontally 

 along the outer wall of the nasal fossa, immediately below the orifice of the 

 antrum. Each bone presents two surfaces, two borders, and two extremities. 



Fig. 120. Right Inferior Turbinated Bone. 

 Inner Surface. 



Fig. 121. Right Inferior Turbinated 

 Bone. Outer SuH':i<-r. 



The internal surface (Fig. 120) is convex, perforated by numerous apertures, 

 and traversed by longitudinal grooves and canals for the lodgment of arteries 



