256 ANATOMICAL TBOBNOLOQT. 



glenoid border of the scapula and the dorsal border of the bra- 

 chium. Here it is easily separated from the subjacent muscles, but 

 nearer both ends it adheres very closely. Dissect the muscle up 

 toward the tip of the metacromion. Lift the overlapping border of 

 the acromio-deltoideus , which lies just ventrad of it near the hu- 

 merus. At the side of the metacromion toward the tip of the acro- 

 mion will be exposed the short, free, ventral border of the muscle. 

 Connect the two borders and reflect the ends. In reflecting the 

 scapular part, avoid cutting into the subjacent infraspinatus, some 

 fibers of which take their origin from the ental surface of the spinx)- 

 deltoideus. The humeral end passes entad of the acromio-deltoi- 

 deus, most of the fibers of which are inserted upon its ectal surface. 



§ 675. Origin. — By short tendinous fibers along the infraspinous 

 border of the mesoscapula and metacromion, from the tuberosity 

 of the former to the glenoid angle of the latter, and from a tendinous 

 raphe between this muscle and the acromio-trapezius. 



Insertion. — By a tendon 1-1.5 cm. long tipon the deltoid ridge 

 of the hameriis ; this extends obliquely distad along the proximal 

 half of the shaft from the middle of the cephalic surface to the ven- 

 tral border. The ectal surface of the tendon is wholly covered by 

 the acromio-trapezius, and the line of insertion is nearly parallel 

 with that of the insertion of the ectal lamina of the ectopectoralis. 



M. ACROMIO-DELTOIDEUS. 



§ 676. Synonymy. —The acromial, or intermediate, part of the human deltoideus, Q., 

 A, 404, Q. , A, I, 199 ; " delto-aeromial," S.-D., A, II, 338 ; part of the " long ahdveUwr du 

 bras," C'h., A, 263 ; part of the long abductor of the arm, or scapular portion of the deltoid, 

 Ch. (Fl.), A, 249 ; part of deltoid, Miv., B, 147. 



Figures, Posture and Exposure.— As with the M. spino-del- 

 toideus. 



General Description. — A short band, from the acromion to the 

 deltoid ridge of the humerus. 



Dissection. — The dorsal — and longer — border was lifted in order 

 to expose the tendon of the spino-deltoideus. The shorter — or ven- 

 tral — border may be traced from the tip of the acromion to a point 

 near the proximal end of the line of insertion of the same muscle, 

 and forms the dorsal limit of the subcutaneous area of the trochiter 

 (marked ce in Fig. 74). 



§ 677. Origin. — By short tendinous fibers along the infraspinous 



