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 conche (Fig. 64, 6), 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 (1) glands. 
Inner surface with the sternohyoid (Fig. 65, ¢), sternothyroid 
(g’), internal jugular vein, longus capitis muscle, the cleido- 
mastoid (4), levator scapule ventralis (z), a large lymphatic 
gland ventrad of the ear, and the splenius (Fig. 73, 4). 
Action.—One muscle turns the head and depresses the 
snout. Both together depress the snout. 
M. sternohyoideus (Fig. 65, ¢).—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, m) 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, 2). 
Relations.—Outer surface with the sternomastoid (Fig.. 
