THE HYOID OR LINGUAL BONE 



153 



removed. Occasionally in removing the maxilla it will be found that the orbital plate can be 

 spared, and this should always be done if possible. A horizontal saw-cut is to be made just 

 below the infraorbital foramen and the bone cut through with a chisel and mallet. Lockwood 

 has pointed out that in removing the maxilla the surgeon must be careful in dividing the nasal 

 process of the maxilla to preserve the internal o;bital or palpebral ligament (Tendo oculi), 

 because this ligament arises from the palpebral fascia, and if it is interfered with the eye will 

 inevitably drop downward. Removal of one-half of the mandible is sometimes required. If 

 possible, the section of the bone should be made to one side of the symphysis, so as to save the 

 genial tubercles and the origin of the Geniohyoglossus muscle, as otherwise the tongue tends to 

 fall backward and may produce suffocation. Having extracted the central or preferably the 

 lateral incisor tooth, a vertical incision is made down to the bone, commencing at the free margin 

 of the lip, and carried to the lower border of the bone; it is then carried along its lower border to 

 the angle and up the posterior margin of the ramus to a level with the lobule of the ear. The flap 

 thus formed is raised by separating all the structures attached to the outer surface of the bone. 

 The jaw is now sawed through at the point where the tooth has been extracted, and the knife 

 passed along the inner side of the mandible, separating the structures attached to this surface. 

 The mandible is then grasped by the surgeon and strongly depressed, so as to bring down the 

 coronoid process and enable the operator to sever the tendon of the Temporal muscle. The 

 mandible can be now further depressed, care being taken to not evert it nor rotate it outward, 

 which would endanger the internal maxillary artery, and the External pterygoid muscle is torn 

 through or divided. The capsular ligament is now opened in front and the lateral ligaments 

 divided, and the mandible removed with a few final touches of the knife. 



The antrum of Highmore occasionally requires tapping for suppuration. This may be done 

 through the socket of a tooth, preferably the first molar, the fangs of which are most intimately 

 connected with the antrum, or through the facial aspect of the bone above the alveolar pro- 

 cess. This latter method does not perhaps afford such efficient drainage, but there is less 

 chance of food finding its way into the cavity. The operation may be performed by incising the 

 mucous membrane above the second molar tooth, and driving a trocar or any sharp-pointed 

 instrument into the cavity. 



THE HYOID OR LINGUAL BONE (OS HYOIDEUM). 



The hyoid bone (Fig. 119) is a bony arch, shaped like a horseshoe, and consist- 

 ing of five segments a body, two greater cornua, and two lesser cornua. It 

 is suspended from the tips of the styloid processes of the temporal bones by 

 ligamentous bands, the stylohyoid ligaments. 



The Body, or basihyal (corpus ossei hyoidei), forms the central part of the 

 bone, and is of a quadrilateral form. 



Surfaces. Its anterior surface (Fig. 119), convex, directed forward and upward, 

 is divided into two parts by a vertical ridge which descends along the median 

 line and is crossed at right angles 

 by a horizontal ridge, so that this 

 surface is divided into four spaces 

 or depressions. At the point of 

 meeting of these two lines is a 

 prominent elevation, the tubercle. 

 The anterior surface gives attach- 

 ment to the Geniohyoid in the 

 greater part of its extent; above, 

 to the Geniohyoglossus; below, to 

 the Mylohyoid, Stylohyoid, and 

 the aponeurosis of the Digastric 

 (suprahyoid aponeurosis) ; and 

 between these to part of the Hyo- 

 glossus. The posterior surface is 

 smooth, concave, directed back- 

 ward and downward, and separated from the epiglottis by the thyrohyoid mem- 

 brane and by a quantity of loose areolar tissue. The lateral surfaces after middle 



FIG. 119. Hyoid bone. Anterior surface. (Enlarged.) 



