ANTERIOR THORACIC REGION. 



295 



the middle, and the middle the lower portion, the fibres of the lower portion being 

 folded backwards upon themselves ; so that those fibres which are lowest in front, 

 become highest at their point of insertion. They all terminate in a flat tendon, 

 about two inches broad, which is inserted into the anterior bicipital ridge of the 

 humerus. This tendon consists of two laminae, placed one in front of the other, 

 and usually blended together below. The anterior, the thicker, receives the cla- 

 vicular and upper half of the sternal portion of the muscles ; the posterior lamina 



Fig. 109. Muscles of the Chest and Front of the Ann. Superficial View. 



receiving the attachment of the lower half of the sternal portion. From this 

 arrangement it results, that the fibres of the upper and middle portions of the 

 muscle are inserted into the lower part of the bicipital ridge ; those of the lower 

 portion, into the upper part. The tendon, at its insertion, is connected with that 

 of the Deltoid ; it sends up an expansion over the bicipital groove to the head of 

 the humerus, another backwards, which lines the groove, and a third to the fascia 

 of the arm. 



