MYOLOGY 85 



Insertion. Passes obliquely upward in front of the spinal column 

 to the inner tubercle on the basal ridge of the basi-temporal bone, 

 by a subcompressed tendon. 



Shape. A somewhat thick fasciculus. 



Relations. Superiorly with the tracheio-mastoideus, inferiorly 

 with the longus colli anterior, and externally with the skin. 



Action. Singly, pulls the head down and to one side; acting with 

 its fellow, pulls the head downwad. 



Tracheio-mastoideus (Fig. 19, No. 16). (Synonym. Longissi- 

 mus capitis et atlantis.) 



Location. Laterally on the anterior portion of the neck. 



Origin. Semitendinous from the diapophyses of the second, the 

 third, the fourth, and the fifth cervical vertebrae. 



Insertion. By subcompressed tendon to the base of the cranium, 

 at the outer tubercle of the basal ridge of the basi-temporal. 



Shape. Flattened from side to side; broad at the posterior por- 

 tion, becomes angular at the anterior portion. 



Action. Singly, pulls the head down and to one side; acting with 

 its fellow, pulls the head downward. 



Interspinales (Fig. 17, A, No. 2). Location. Superior to the 

 vertebra. 



Origin and Insertion. A series of muscles connecting the superior 

 neural spines of the cervical vertebrae. 



Shape. Thin, flat. 



Relations. Anteriorly the posterior border of the vertebrae in front 

 and posteriorly the anterior border of the succeeding vertebrae, 

 inferiorly by the vertebrae. 



Action. To approximate the spinous portion of the vertebrae. 



Interarticulares (Fig. 17, No. A, 4). Location. Supero-laterally 

 to the vertebrae. Between the postzygapophysis. 



Origin and Insertion. From the posterior margin of the ring of 

 the atlas to the postzygapophysis of the axis. Then in the suc- 

 ceeding vertebrae from the postzygapophysis of the vertebra to 

 the same of the succeeding vertebra. 



Shape. Muscular bundle. 



Relations. Inferiorly with the vertebrae. Supero-laterally with 

 the obliquo-transversales. 



Action. Aids in approximating the vertebrae in a supero-lateral 

 direction. 



