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 tlie 

 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-glosstis hrevis of Percivall) (Plate 31). 

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

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

 aspect of the glossal process, body, and thyroid cornu 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 tlie tongue, and also the lingual artery and the 9th 

 nerve. 



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

 the articulation between the great and the small cornu 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 ariswig 

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

 great hyo-glossus and over the lingvial artery, and readies the root of the 

 tongue. 



Action. — To narrow the fauces. 



Directions. — The next two muscles lie internal to tlie small cornu. To 

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

 joint pulled outwards. 



The Hyoideus Transversus 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 arisiiu/ from 

 the lower extremity of the small cornu 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 Briihl, in 1S50, as tiie middle dcsceadhig sti/lo- 

 filon^a.''. 



