DISSECTION OF THE HEAD AND NECK. 205 



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 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 arising 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. 



Action. — To aid in retracting the tongue. 



The Genio-glossus, or Genio-hyo-glossus (Plates 31 and 32). This 

 muscle is fan-shaped. Its origin is from a depression on the inner 

 surface of the horizontal ramus of the lower jaw, near the sym- 

 physis. From this point, and from a tendon at the posterior edge 

 of the muscle, its fibres radiate into the tip, centre, and base of 

 the tongue, beneath those of the stylo-glossus and great hyo-glossus 

 muscles. 



Action. — The upper fibres protrude the tongue by pulling downwards 

 its base, the lower fibres retract the free portion of the tongue, and 

 the intermediate fibres (or the entire muscle) depress the tongue as a 

 whole towards the floor of the mouth. 



If the dissector will raise the posterior tendinous edge of the muscle, 

 he will find that he has now reached the middle plane of the tongue, 

 which is here occupied by a quantity of connective-tissue and fat 

 between the right and left genio-glossus muscles. 



The Genio-hyoideus (Plates 31 and 32). This is a muscle of the 

 hyoid bone, rather than of the tongue. It is elongated and fusiform 

 in shape, and is placed beneath the tongue, near the middle line. It 

 arises from the inner surface of the horizontal ramus, close to the 

 symphysis ; and, passing upwards along the inner edge of the mylo- 



