200 



THE SKELETON. 



is much longer than the vertical, and even after it is fully ossified the whole bone 

 is at first remarkable for its shortness. 



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

 inferior turbinated, vomer, and opposite palate. 



Attachment of Muscles. To four : the Tensor palati, Azygos uvulae, Internal 

 pterygoid, and Superior constrictor of the pharynx. 



The Inferior Turbinated Bones. 



The Inferior Turbinated Bones (turbo, a whirl) 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 hori- 

 zontally 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. 



The internal surface (Fig. 163) is convex, perforated by numerous apertures, 

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



FIG. 163. Right inferior turbinated bone. Internal 

 surface. 



FIG. 164 Right 

 External surface. 



inferior turbinated bone. 



veins. In the recent state it is covered by the lining membrane of the nose. The 

 external surface is concave (Fig. 164), and forms part of the inferior meatus. Its 

 upper border is thin, irregular, and connected to various bones along the outer 

 wall of the nose. It may be divided into three portions : of these, the anterior 

 articulates with the inferior turbinated crest of the superior maxillary bone ; the 

 posterior with the inferior turbinated crest of the palate bone ; the middle portion 

 of the superior border presents three well-marked processes, which vary much in 

 their size and form. Of these, the anterior and smallest is situated at the junction 

 of the anterior fourth with the posterior three-fourths of the bone : it is small and 

 pointed, and is called the lachrymal process ; it articulates by its apex with the 

 anterior inferior angle of the lachrymal bone, and by its margins with the groove 

 on the back of the nasal process of the superior maxillary, and thus assists in 

 forming the canal for the nasal duct. At the junction of the two middle fourths of 

 the bone, but encroaching on its posterior fourth, a broad, thin plate, the ethmoidal 

 process, ascends to join the unciform process of the ethmoid ; from the lower border 

 of this process a thin lamina of bone curves downward and outward, articulating 

 by its lower margin with the lower edge of the orifice of the antrum : it is called 

 the maxillary process, and fixes the bone firmly on to the outer wall of the nasal 

 fossa. The inferior border is free, thick, and cellular in structure, more especially 

 in the middle of the bone. Both extremities are more or less narrow and pointed, 

 the posterior being the more tapering. If the bone is held so that its outer con- 

 cave surface is directed backward (i. e. toward the holder), and its superior border, 

 from which the lachrymal and ethmoidal processes project, upward, the lachrymal 

 process will be directed to the side to which the bone belongs. 1 



Development. By a single centre, which makes its appearance about the 

 middle of foetal life. 



Articulations. With four bones : one of the cranium, the ethmoid, and three 

 of the face, the superior maxillary, lachrymal, and palate. 



No muscles are attached to this bone. 



1 If the lachrymal process is broken off, as is often the case, the side to which the bone belongs 

 may be known by recollecting that the maxillary process is nearer the back than the front of the bone- 



