96 



Its action is to rotate the arm inwards, and extend it upon the* body ; 

 and it also serves mechanically, to keep the posterior angle of the 

 scapula close to the ribs, for in 



passing to its insertion in the hu- 16, 

 merus, it overlaps the scapula over 

 the space marked (a) in Fig. 17, 

 which also represents the origin of 

 the teres inferior muscle. 



The second part of the true la- 

 tissimus dor si muscle, (2) called 

 scapulo-costalis, has an abdominal 

 origin (with indigitations), corre- 

 sponding to the dorsal origin of the 

 humero-dor salts, beneath which it 

 passes to be inserted on the inner 

 face of the cartilaginous prolonga- 

 tion of the vertebral edge of the 

 scapula marked a in Fig. 16. These 

 two muscles form a portion of an 

 inner elliptical plane of converg- 

 ing fibres, corresponding to the 

 outer plane of the superficial latis- 

 simus dorsi, whose function as a 

 swimming muscle has been already 

 noticed. 



11. II. teres inferior, . . ^ oz, 



Origin ; marked a in Fig. 17. 

 Insertion ; by tendon common 

 to it and latissimus dorsi hu~ 

 mero-dorsalis into line marked 

 I, in Fig. 16. 



12. M. teres superior, . 1*47 oz. 



Origin ; triangular space on 

 outer side of scapula, marked 

 c, Fig. 1 7, and from spine of 

 scapula. 



Insertion ; outer side of pec- 

 toral ridge, along line marked 

 e, Fig. 17. 



13. M. supraspinous, . 1-85 oz. 



1 4. Infraspinatus, . . 0-47 oz. 



Inserted just above the teres 



superior, on the humerus. 

 lb. M. subscapular is, . . 5*5 oz. 

 16. M. triceps, . . . . 5*0 oz. 



This muscle has two scapular and one humeral head ; one of the 

 scapular heads is marked b, Fig. 17, the other is near the glenoid cavity, 

 and the humeral head is as usual in all mammals. 



INNER SIDE OF LEFT ANTERIOR LIMB OF SEAL. 



a, Insertion of M. latissimus dohi sccqmlo- 

 costalis. 



„ 31. latissimus dorsi himero- 



dorsalis, and M. tares infe- 

 rior. 



