50 ANATOMY OF THE RABBIT 



scapulae m. (ii), then between the rhomboideus major and 

 minor mm. (9) and on to insert into the scapula. 



6. Cleidomastoid m.: Mastoid process, fused with occipito- 

 scapularis (5); to clavicle. Rotates head, or depresses snout 

 when clavicle is fixed, or may raise sternum when head is fixed. 

 Transect. This and the next muscle (7) lie parallel, have 

 similar functions and represent the sternocleidomastoid m. of 

 man. 



7 . Sternomastoid m. : Manubrium sterni ; to mastoid process. 

 Transect. 



8. Pectoral mm.: All of the sternal bones; to superior limb. 

 Adduct and rotate superior limb. Probe, but do not attempt 

 to establish the insertions definitely until the clavodeltoid m. 

 (12) has been transected. Transect each muscle at a different 

 level or angle. This group of muscles is so loose in texture that 

 the probe will readily pass through at any point. However, 

 only three (Hyman) to five (Bensley) separate muscles are 

 described as comprising the entire group. In origin and in other 

 ways these muscles do not agree with the pectorals of man. 



8a. Pectoralis primus (p. tenuis) m.: Manubrium sterni, 

 with platysma m. (p. 72) and sternomastoid m. (7); to deltoid 

 ridge and cranial side of humerus, under clavodeltoid m. (12). 

 This narrow slip of muscle covers the cranial border of the 

 pectoraHs major (86). It is easily identified by being very 

 narrow, superficial, most anterior of the group, and usually more 

 reddish in color. 



8b. Pectoralis major (p. secundus) m.: Manubrium and 

 first two sternebrae; to proximal two-thirds of craniolateral 

 side of humerus, with pectoralis primus (8a). Adducts and 

 rotates superior limb. 



8c. Pectoralis minor (p. tertius) m.: Entire ventrolateral 

 surface of sternum; to proximal third of humerus and fascia 

 around shoulder joint and clavicle. Adducts superior limb. 

 This muscle forms the deep portion of the bicipital arch. As 

 here described it includes the pectoralis quartus of Bensley 

 (p. 211), and is much the largest of the group. 



