386 



THE MUSCLES AND FASCIA 



other, at their origin, by a triangular cellular interval, but become graduall; 

 blended, below the middle of the neck, into a thick, rounded muscle, which i 

 inserted, by a strong tendon, into the outer surface of the mastoid process of th 

 temporal bone, from its apex to its superior border, and by a thin aponeurosi 

 into the outer half of the superior curved line of the occipital bone. The Sterno 

 mastoid varies much in its extent of attachment to the clavicle; in one case th 

 clavicular may be as narrow as the sternal portion; in another, the former, may bi 

 as much as three inches in breadth. When the clavicular origin is broad, it i 

 occasionally subdivided into numerous slips separated by narrow intervals 

 More rarely, the corresponding margins of the Sternomastoid and Trapeziu 

 have been found in contact. 





vOO. Muscles of the neck and boundaries of the triangles. 







*. The Sternomastoid muscle divides the quadrilateral area of the side 



([ngles, an anterior and a posterior. The boundaries of the anterioi 



ie median line of the neck; above, the lower border of the body of the 



iary line drawn from the angle of the mandible to the mastoid process: 



der of the Sternomastoid muscle. The apex of the triangle is at the 



mm. The boundaries of the posterior triangle are, in front, the pos- 



' ' " fhird of the clavicle; behind, the anterior 



the ( 'ding of the Sternomastoid ;tnd 



and ['' orn which it is 



; .al branches of the cervical r ; 



i in relation with the 



>i, Ster no- 



nius and 



; i ternal 





