MUSCLES OF THE ANTER10E LIMBS. 253 



which singularly augment the tenacity of the muscle ; the superficial fibres 

 are spread over the internal surface in glistening, nacrous layers. 



Attachments. The subscapularis takes its origin from the whole extent 

 of the fossa whose name it bears. Its movable insertion takes place on the 

 internal tubercle, by means of a voluminous tendon it offers at its inferior 

 extremity. A particular small synovial bursa facilitates the gliding of this 

 tendon over the eminence into which it is inserted. 



Relations. The external face of the muscle is in contact with the scapula. 

 Its internal face is applied against the great serratus, from which it is 

 separated by a thick layer of cellular tissue, as well as by the rudimentary 

 fascia covering the three muscles of the internal scapular region in common. 

 Its anterior border, margined by the superspinatus, adheres closely to that 

 muscle in its upper two-thirds, and forms with it, by its inferior third, the 

 intermuscular space that lodges the subscapular vessels and nerves. Its 

 posterior border responds to the adductor of the arm, with which it also 

 unites for the greater part of its extent ; it is isolated from this muscle, in 

 its inferior third, by the interspace lodging the subscapular vessels and 

 nerves. Its terminal tendon covers the capsule of the scapulo-humeral 

 articulation, which it powerfully binds ; it is in part covered by the tendon 

 of origin of the coraco-humeralis muscle, which glides over its surface as on 

 a pulley, by means of a synovial bursa. 



Action. This muscle is principally, and perhaps exclusively, an adductor 

 of the arm. It may be admitted, however, that it rotates the humerus 

 inwards. 



Adductor of the Arm, or Teres Major. (Fig. 121, 4.) 



Synonyms. Subscapulo-humeralis Girard. (Teres major Percivall. Great 

 scapulo-humeralis Leyh."j 



Form Situation Direction. A long muscle, flattened on both sides, 

 bulging in its middle, contracted at its extremities, thick at its anterior, and 

 thin at its posterior border. It is situated behind the preceding, in the 

 same oblique direction, and is parallel with the posterior portion of the 

 long abductor, which it appears to repeat in the internal scapular region. 



Structure. It is almost entirely muscular, showing only some tendinous 

 fibres at its external surface and upper extremity. Its inferior extremity is 

 terminated by a flat tendon, which also belongs to the great dorsal, an<J 

 which has been already described (see page 203). 



Attachments. -It arises from the dorsal angle of the scapula, and the 

 posterior border of the subscapular muscle origin ; it passes to the circular 

 imprint on the body of the humerus, to be attached by its inferior tendon 

 termination. 



Relations. Outwards, with the aponeurosis of the great dorsal and that 

 of the long extensor of the fore-arm, which isolates it from the large 

 extensor muscle ; inwards, with the great serratus, from which it is separated 

 by the fibrous and cellular layers mentioned in the description of the sub- 

 scapularis. Its inferior extremity covers the short flexor and middle extensor 

 of the fore-arm ; it is covered by the long branch of the coraco-humeralis, 

 and by the vascular and nervous trunks which send their ramifications to 

 the arm, fore-arm, and foot. 



Action. This muscle adducts the arm, and causes it to rotate inwards. 

 If it contracts at the same time as the long abductor, it directly flexes the 

 humerus. 



