162 



Muscles of the Thorax. 



A. mammar. int. 



V.V mammar. ink 



216. Muscidus triangularis sterni seu sterno-costalis. 



The Thoracic Muscles, third Lave r : 



Muscidi intcrcostcdcs cxterni. Orig. : Lower borders of the eleven upper 

 ribs. Insert. : Each into the upper border of the rib below up to the com- 

 mencement of the costal cartilages ; beyond these points at which the 

 muscles cease, the spaces are occupied by the aponeurotic Lirjamentum 

 coruscans. 



MuscuU mtcrcostalcs intcrni. Orig. : Lower borders of the eleven upper 

 ribs and costal cartilages. Insert. : Each into the upper border of the rib 

 below throughout its entire length. " 



J/. triangular is sterni at the posterior surface of the sternum and 

 the costal cartilages. Orig. : Xiphoid appendix and body of the sternum. 

 Insert. : By fleshy digitations into the posterior surface of the third to 

 the sixth costal cartilages. 



All these muscles act in respiration. 



