INFERIOR TURBINATED BONE. 



91 



Fig. 53. Right Inferior Turbinated Bone. Inner 

 Surface. 



Attachment of Muscles. The Tensor palati, Azygos uvulae, Internal and External 

 pterygoid. 



\ 



THE INFERIOR TURBINATED BONES. 



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

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

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

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

 antrurn. Bach bone presents two surfaces, two borders, and two extremities. 



The internal surface (fig. 53) is convex, perforated by numerous apertures, and 

 traversed by longitudinal grooves 

 and canals for the lodgment of arte- 

 ries and veins. In the recent state it 

 is covered by the lining membrane of 

 the nose. The external surface is con- 

 cave (fig. 54), and forms part of the 

 inferior meatus. Its upper border is 

 thin, irregular, and connected to vari- 

 ous bones along the outer wall of the 

 nose. It may be divided into three 

 portions; of these, the anterior arti- 

 culates 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 lachry- 

 mal process, for it articulates with the ante- 

 rior inferior angle of the lachrymal bone, 

 and by its margins with the groove on 

 the back of the nasal process of the supe- 

 rior maxillary, and thus assists in forming 

 the lachrymal canal. At the junction of 

 the two middle fourths of the bone, but en- 

 croaching on the latter, 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 downwards and outwards, hooking over the lower edge of 

 the orifice of the antrum, which it narrows below ; it is called the maxillary pro- 

 cess, and fixes the bone firmly on to the outer wall of the nasal fossa. The infe- 

 rior border is free, thick and cellular in structure, more especially in the centre 

 of the bone. Both extremities are more or less narrow and pointed. If the bone 

 is held so that its outer concave surface is directed backwards (i. e., towards the 

 holder), and its superior border, from which the lachrymal and ethmoidal pro- 

 cesses project, upwards, the lachrymal process will be directed to the side to which 

 the bone belongs. 



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

 of fcetal 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. 



Fig. 54. Right Inferior Turbinated Bone. 

 Outer Surface. 



