INTERCOSTAL MUSCLES. 



307 



Commencing at the anterior extremities of the cartih^gcs of the ribs, 

 they extend as far back as a point within the angles of those bones. 

 The fibres incline downwards and backwards, crossing- those of the 

 external intercostals ; they are, however, somewhat shorter and less 

 oblique in their direction. 



Relat'wnn. — The internal are separated from the external intercostal muscles at 

 the back of the spaces by the intercostal vessels and nerves ; they are Ikied 

 internally by the pleui-a. 



Fiff. 220. 



Fig. 220. — View op the Deep Muscles of the Anterior Wall of the Thorax, seek 

 FROM BEHIND (modified from Luschka). (A. T.) ^ 



a, back of the manubrium of the sternum ; h, clavicles ; I to XI, the anterior parts 

 of eleven ribs and costal cartilages ; 1, 1', stemo-thyroid muscles, that of the right side 

 being cftt short to show more fully the next muscle ; 2, 2', the sternodij'oids ; 3, trian- 

 gularis sterni ; 4, upper part of transversalis abdominis imited in 4', 4', the back of the 

 linea alba ; 5, attachments of the diaphragm to the lower ribs (the twelfth not represented 

 in the figure), indigitating Avith those of the transversalis ; 5', the two slips to the ensi- 

 form process ; 6, internal layer of intercostal muscles extending to the sternum, shown 

 in all the spaces on the right side, but only in the two uppermost of the left side ; 7, in 

 the lower spaces of the left side, indicates the external layer of intercostal muscles 

 exposed by removing the internal layer. 



X 2 



