OF THE HEAD AND NECK GENERALLY. 207 



lower jaw. There are two fleshy belUes to this muscle, one 

 at either end, divided by an intervening tendon ; which 

 plays through a synovial loop upon the sides of the body of 

 the OS hyoides. 



Genio hyoideus. Origin. By tendon from the symphy- 

 sis of the lower jaw. Insertion. Into the spur process of 

 the OS hyoides by tendon. Action. To draw forward the 

 OS hyoides. 



Hyoideus magnus. Origin. From behind the large horn 

 of the OS hyoides. Insertion Into the side of the body of 

 the OS hyoides by tendon, which forms the loop the digas- 

 tricus plays through. Action. To raise the body of the os 

 hyoides, and with it the larynx. 



Hyoideus parvus. Origin. From the border of the 

 large horn of the os hyoides, near to its lower articulation. 

 Insertion. Into the body of the lesser cornu, and into the 

 body of the os hyoides. Action. To raise the lower cornu 

 of the OS hyoides. 



Stylo hyoideus. Origin. From the styloid process of 

 the occiput. Insertion. Into the large horn of the os 

 hyoides. Action. To pull the large horn backward, down- 

 ward, and outward. 



No one can have attentively read the description of the 

 foregoing muscles, or have any idea concerning them, but 

 must have seen the much greater power of those wdiich 

 close, than those which lower, the jaw. The difference 

 is such as to admit of no comparison ; hence during 

 tetanus, when all the muscles are spasmodically affected, 

 the mouth is locked, not because the feebler muscles that 

 lower the jaw escape from morbid contraction, but because 

 these can offer no opposition to the powerful and enduring 

 masses which shut fast the cavity. 



Another fact must strike every one ; that is, the large 

 number of muscles which go to the os hyoides, and there- 

 fore indirectly to the larynx. Yet the last organ is spoken 

 of by most teachers as though it were fixed ; while its situa- 

 tion is as loosely pendent, and its motor power as multi- 

 farious, as that of any part in the entire body. 



OF the head and neck generally. 

 The common integuments of the neck and face are similar 



