MYOLOGY 35 



arising from the hyoid, and it is inserted upon the thyroid 

 cartilage. At first glance this might be mistaken for an 

 anterior extension of the sternothyroid, as it is of about the 

 same width as that muscle. 



M. geniohyoideus (figs. 8, 24) lies deep to the mylo- 

 hyoid and close to its fellow along the medial line. Origin 

 is from the medial surface of the mandibular ramus just 

 caudad to the symphysis. The fibers run caudad and are 

 inserted onto the cranial border of the hyoid deep to the 

 insertion of the mylohyoid. 



Innervation of these two muscles is by means of the 

 hypoglossal nerve. 



3. Deep lateral and sub vertebral group 



Under this heading belong the 



Mm. scalenus longus capitis 



longus colli rectus capitis anterior 



M. scalenus (figs. 7, 8, 9). This, with some difficulty, 

 is divisible into three parts. The portion corresponding 

 to the scalenus anticus arises from the first rib about where 

 this joins its cartilage, and is inserted upon the transverse 

 processes of several of the cervical vertebrae. 



The medial division lying superficial to the original 

 portion of the levator scapulae has origin from the third 

 and fourth ribs. Extending craniad from beneath the 

 caudal slip of the levator scapulae, insertion is by muscle 

 fibers and investing aponeurosis chiefly upon the atlas, but 

 to a slight extent upon the transverse processes of most if 

 not all of the remaining cervical vertebrae as well. 



In Neotoma, origin is from the fourth and fifth ribs, 

 while in Teonoma, it is from the fifth and sixth. 



The third and most ventral division of the scalenus 

 has origin by slips from the third, fourth and fifth ribs. 

 These at once unite and the resulting muscle band emerges 



