MUSCULAR SYSTEM OF THE RED HOWLING MONKEY 



101 



border of the coracohiimeral ligament. Its lateral margin is covered 

 by the medial bundles of m. pectoralis abdominis. These two muscles 

 are closely joined by connective tissue, but still clearly differentiated 

 from each other. Sirena (1871) thought that they formed a single 

 pectoralis minor, but Campbell (1937) was able to identify them 

 separately in Alouatta palliata. 



Nerve supply: The medial pectoral nerve with contributions 

 from C VI and VII or VIII (fig. 26). 



Figure 31. — Ventral view of the thorax and shoulder (1, m. pectoralis minor; 2, m. pecto- 

 ralis abdominalis; 3, m. biceps brachii; 4, m. obliquus externus abdominis; 5, m. 

 brachialis; 6, m. pectoralis major; 7, m. deltoideus; 8, m. sternocleidomastoideus). 



M. jjectoralis abdominalis: This is also an elongated muscle broader 

 at its costal than at its humeral end. It arises by fleshy fibers from 

 the rectus sheath in front of approximately the sixth intercostal space 

 and cartilage. This origin is higher in the female. The ventrally com- 

 pressed belly reaches the shoulder where it changes into a progres- 



