DISSECTION OF THE HEAD AND NECK. 199 



lower extremity. It extends along the side of the tongue to near its 

 tip, where its fibres are confounded on the middle line with those of the 

 opposite muscle. 



Action.~To retract the tongue, and at the same time to incline it 

 laterally if only one muscle acts. 



The Great Hyo-glossus {Hyo-glossus hrevis of Percivall) (Plate 31). 

 To expose this muscle fully, the stylo-glossus should be cut near its 

 origm and reflected. The great hyo-glossus arises from the lateral 

 aspect of the glossal process, body, and thyroid comu of the hyoid bone. 

 Its fibres extend obliquely forwards and downwards across the side of 

 the fixed portion of the tongue, and turn inwards on reaching the 

 dorsum. 



Action. — To retract and depress the tongue. 



Directions. — Incise the origin of the foregoing muscle, and raise it 

 forwards after the manner of Plate 32. This will expose more fully the 

 other muscles of the tongue, and also the lingual artery and the 9th 

 nerve. 



The Middle Hyo-glossus Muscle* (Plate 32) arises from the front of 

 the articxilation between the great and the small comu of the hyoid bone. 

 In passing downwards beneath the great hyo-glossus it crosses over the 

 lingual artery. Its fibres are confounded in front with those of the 

 palato-glossus. 



Action. — It is a feeble retractor of the tongue. 



The Palato-glossus (Plate 32). This is a small, thin muscle arising 

 from the edge of the soft palate. It passes downwards beneath the 

 great hyo-glossus and over the lingual artery, and reaches the root of the 

 tongue. 



Action. — To narrow the fauces. 



Directions. — The next two muscles lie internal to the small comu. To 

 expose them, the middle hyo-glossus should be cut, and the intercomual 

 joint pulled outwards. 



The Hyoidbus Teansveesus is peculiar in that it is an unpaired 

 muscle without a median raphe. It extends transversely across the 

 middle line, being attached at its extremities to the small cornua in the 

 whole of their extent. When relaxed it passes between its points of 

 attachment with a curve whose concavity is directed upwards and 

 forwards. 



Action. — To raise the root of the tongue. 



The Small Hyo-Glossus. This is a muscle of small size arising from 

 the lower extremity of the small comu and from the body of the hyoid 

 bone. It passes forwards over the preceding muscle and terminates in 

 the root of the tongue. 



* This, apparently, is the muscle first described by Brflhl, in 1S50, as the viiddle descending stylo- 

 glossus. 



