140 THE MUSCLES. 



The origin extends from the cranial end of the manubrium 

 along the midventral line as far as the caudal border of the 

 cricoid cartilage, and is in two parts. The caudal portion 

 arises from the lateral surface of the manubrium along the 

 dorsal half of its cranial end, and from the median raphe for 

 about one centimeter craniad of the manubrium. Its fibres are 

 parallel and tend to diverge into two layers. The cranial 

 portion arises by means of fibres which cover the median line 

 and interdigitate with the fibres of the opposite muscle between 

 the cricoid cartilage and a point a few millimeters craniad of 

 the manubrium. Its caudal border is thus overlaid by the 

 caudal portion. Its fibres converge and join those of the 

 caudal portion. The muscle passes dorsocraniad and is 



Inserted by means of a flat tendon into the lateral half of 

 the lambdoidal ridge and into a continuation of the ridge onto 

 the mastoid portion of the temporal bone as far as the mastoid 

 process. The thickest part of the tendon is inserted into the 

 mastoid process. 



Relations. Outer surface at the caudal end with the pec- 

 toralis major (Fig. 65, /); in the middle part with the platysma, 

 the depressor conchse (Fig. 64, b}, and with the external jugu- 

 lar vein (Fig. 65, 5), which crosses it obliquely; at the cranial 

 end with the submaxillary (Fig. 65, 2) and parotid (i) glands. 

 Inner surface with the sternohyoid (Fig. 65, e), sternothyroid 

 ('), internal jugular vein, longus capitis muscle, the cleido- 

 mastoid (/), levator scapulae ventralis (z), a large lymphatic 

 gland ventrad of the ear, and the splenius (Fig. 73, b]. 



Action. One muscle turns the head and depresses the 

 snout. Both together depress the snout. 



M. sternohyoideus (Fig. 65, e). A slender muscle on the 

 midventral line of the neck close to the opposite muscle. 



Origin from the cranial border of the first costal cartilage. 

 The muscle passes craniad closely united near its caudal end 

 to the sternothyroid (g'}. 



Insertion (Fig. 67, ?;/) into the outer half of the ventral sur- 

 face of the body of the hyoid bone caudad of the origin of the 

 geniohyoid (Fig. 67, g). 



Relations. Outer surface with the sternomastoid (Fig. 



