244 ANATOMICAL TECHNOLOGY. 



insertion of the entire entopectoralis in some monkeys and — more 

 commonly — in man. As to the frequency of the humeral insertion 

 of the human M. entopectoralis, see Macalister, Proc. Roy. Irish 

 Acad., X, 142. 



M. XIPHI-HDMEBALIS. 



§ 660. Synonymy. — " Le second chef du grand pectoral" S.-D., A, II, 341 ; pectoralis, 

 part 4, Miv„ B, 147. 



Figures. — Part of ectal aspect (73) ; humeral end, reflected (73) ; insertion spots (69). 



Exposure. — By the reflection of the other portions of the pec- 

 toral mass. 



General Description. — The longest and most slender member 

 of the pectoralis group ; from the median raphe at the epigastrium 

 to the proximal end of the humerus. The length of the cephalic 

 border is sometimes 20 cm., while the width at the middle is only 

 4 mm. 



Dissection and Origin. — The caudal border was exposed during 

 the dissection of the MM. latissimus and dermo-humeralis ; the 

 cephalic border during the dissection of the caudal division of the 

 M. entopectoralis. Transect the muscle near the middle. 



In reflecting the proximal part, note that, 1-2 cm. from the 

 meson, the loose connective tissue between it and the thoracic parie- 

 tes is sometimes replaced by a firm tendinous attachment to the 8th 

 costal cartilage and to the fascia covering the M. rectus ; the mus- 

 cular fibers cease at about the same point, and the thin, wide tendon 

 is connected with its platetrope by a median raphe, the position of 

 which, as regards the xiphisternum, is quite variable. 



§ 661. Insertion. — The humeral connections are complex and 

 variable. In passing the latissimus, it. is usually connected, by 

 tendinous fibers, with the ental surface of that muscle, then, indi- 

 rectly, with the entopectoralis and the other elements of the bicipital 

 arch. Just beyond this connection the narrow muscle is replaced 

 by a tendon which usually widens as it nears the humerus. In the 

 broad sheet so formed may usually be detected three more or less 

 distinct bands with attachments as follows (Fig. 66, 71, 73) : (A) 

 upon the bicipital border of the trochin, just cephalad of the inser- 

 tion of the M. subscapularis ; (B) and (C) just caudad of the inser- 

 tions of the cephalic and caudal divisions of the entopectoralis. As 

 a whole, therefore, the tendon spans the bicipital groove. 



