M. LATISSIMUS. 229 



633. Upon Figures 68-71 are represented the insertion areas or lines of the following 

 muscles ; the list includes all which are inserted upon the huraerus : 



Acromio ddtoideus (68), 676 ; coracoideus, caput breve (70), capnt longum (71), 688; 

 ectopectoralis, Im. ectalis (68, 63), 649 ; ectopectoralis, Im. entails, do. caudalis (69), 653 ; 

 ectopectomlis, Im. entali*, dv. cephalica (68, 69), 651 ; entopectoralis, dv. caudalis (69, 70), 

 656 ; entopectoralis, dv. cephalica (69, 70), 658 ; infraspinatus (68), 678 ; micostalis 

 (63), 679 ; spino-deltoideus (68), 674 ; supraspinatus (68, 69), 675 ; teres (69, 70), 680 ; 

 xipid-humcralis (69), 660. 



As stated in 670, the insertion of the coracoideus, caput hngum, is so variable that 

 the area is here indicated on Fig. 71 by an interrogation point. 



634. The origin areas or lines of the following 13 muscles are represented upon 

 Fig. 68-71 : 



Brachial's (68, 71), 692; entotriceps, dv. breris (70, 71), 688, dv. caudalis (70, 71), 

 637, dv. cephalica (71), 689, dv. intermedia (68, 71), 686 ; extensor digitorum corn- 

 munis (68, 71), 697 ; extensor minimi (68, 71), 698 ; extensor radialis brevior (68), 696 ; 

 ext. rad. longior (63, 71), 694 ; extensor ulnaris (68), 699 ; flexor radialis (70), 702 ; 

 pronator teres (70, 71), 701 ; supinator longus (71), 690. 



M. LATISS1MUS. 



635. Synonymy. Latissimus dorsi, Q., A, 1,189; G., A, 374; "grand dorsal," 

 S.-D., A, II, 339 ; " grand dorsal," Ch., A, 217, Fig. 90 ; great dorsal, Ch. (Fl.), A, 203; 

 latissimus dorsi, Miv., B, 137. 



Figures. Ectal aspect (66, 67, 74) ; ental aspect (72, 73, 75) ; insertion area (69, 70) . 

 tran section (99, 100). 



Posture. Latericumbent, the venter toward the dissector; a 

 block transversely under the thorax just caudad of the elbows. 



Exposure. Most of the muscle has been exposed by the re- 

 moval of the spino-trapezius and dermo-humeralis, and needs only 

 to have its ectal surface cleared. If the caudal region of the body 

 has not been removed, the corresponding part of the latlssimus 

 may be exposed by dividing the skin and the dermo-humeralis 

 along a dorso-caudal line from the already exposed caudo-ventral 

 border of the latissimus to the crista ilii ( 230, Fig. 51) of the op- 

 posite side, and reflecting the flap so formed across the dorsimeson. 



General Description. A large triangular sheet, covering rather 

 more than the dorso-cephalic half of the abdomen and thorax, ex- 

 cepting so much of the latter as is between the scapulae. It arises 

 at the dorsimeson between the pelvis and the 5th thoracic spine, 

 and is inserted upon the humerus, forming part of the bicipital 

 arch (Fig. 73). 



Dissection. Lift the caudo-ventral border where it crosses the 

 7th rib (which is also the 7th counting from the last), and trace it 

 both ways for 2-3 cm. Trace the cephalic border from the vertebral 



