122 THE MUSCLES. 



Relations. Its outer surface is covered caudad by the 

 cutaneus maximus, and craniad by the spinotrapezius (Fig. 

 68, /) and the long head of the triceps (Fig. 68, ). The 

 cranial border comes into relation with the spinotrapezius (_/) 

 and teres major (Fig. 77, r). The caudal border is in contact 

 at the ventral end with the xiphihumeralis (Fig. 65, /) and 

 pectoralis minor (Fig. 65, 0). The inner surface of the latissi- 

 mus covers near its cranioventral end parts of the xiphihumer- 

 alis (Fig. 68, ;/), pectoralis minor (Fig. 68, <?), teres major 

 (Fig. 77, r), and serratus anterior (Fig. 73, /). The caudal 

 border covers a portion of the obliquus externus abdominis 

 (Fig. 68, /); the dorsal and middle portions cover parts of the 

 longissimus dorsi (Fig. 69, /"), the spinalis dorsi (Fig. 69, g], 

 the serratus posterior superior (Fig. 73, /), and serratus pos- 

 terior inferior (Fig. 73, n). 



Action. Pulls the arm caudodorsad. 



M. serratus anterior and levator scapulae (Fig. 73, /'and //) 

 in the cat are continuous at both origin and insertion, and it is 

 barely possible to separate their contiguous borders without 

 cutting the fibres. The muscle extends from the transverse 

 processes of the last five cervical vertebrae and from the first 

 nine or ten ribs to the medial surface of the scapula near its 

 vertebral margin (Fig. 78, c and d). 



M. serratus anterior (or serratus magnus) (Fig. 73, z). 



Origin. From the first nine or ten ribs in as many sub- 

 divisions. The first subdivision arises from the whole or nearly 

 the whole of the caudal border of the first rib. The next four 

 or five arise either from the ribs or from the costal cartilages 

 near or at their junction with the ribs. The last four subdivi- 

 sions arise from the ribs at increasing distances from the carti- 

 lages. The fibres converge and the subdivisions join one 

 another. 



Insertion (Fig. 78, c] into a narrow area on the medial sur- 

 face of the scapula near the vertebral border. The glenoid 

 half of the insertion is by a short tendon, the remainder by 

 muscle-fibres. 



Relations. Outer (lateral) surface with the latissimus dorsi 

 (Fig. 68, z), teres major (Fig. 77, c). subscapularis (Fig. 



