THE ANATOMY OF THE INDIAN ELEPHANT. 17 



Anconceiis arises chiefly from the back of the external condy- 

 loid ridge; some of the upper fibres taking origin from the 

 posterior border of the elastic ligament of the fore-arm, and some 

 of the deeper fibres from the superior tendon of extensor carpi 

 ulnaris. From this origin the muscle spreads out, and is inserted 

 into a triangular surface on the outer side of the ulna, imme- 

 diately beneath the olecranon. The apex of this triangle is 

 situated nearly half way down the shaft. Below, the muscle is 

 overlaid by extensor carpi ulnaris, and above by a dense fascia. 



C. and L.— 274-5 ; 276-7 ; 283, fig. 2 ; 284, fig. 2 (u). 



Extensor pollicis arises from nearly the whole anterior surface 

 of the radius, with the exception of a small part towards the 

 lower end of the bone, from the interosseous membrane and 

 from the adjacent surface of the ulna. At the lower part of the 

 radius the muscle is twisted upon itself, so that the external 

 fibres become anterior, and ultimately internal. The tendon 

 passes through a special sheath on the inner side of the end of 

 the radius, and is inserted into the base of the 1st digit. The 

 tendon is connected by a lateral expansion with that of the 

 extensor indicis. A large vein and the posterior interosseous 

 nerve pass between the radial and ulnar origins of the muscle. 

 Several large veins, communicating with the plexus in front of 

 the elbow-joint, lie in the interosseous space beneath the muscle. 



C. and L.— 274-5 ; 276-7 ; 283, figs. 1, 2 ; 284, fig. 1 {t). 



Extensor indicis. — Small and pointed above, where it arises 

 from the front of the ulna close to the head of the radius, and 

 below this from the intermuscular septum on the outer side 

 between it and extensor minimi digiti, and on the inner side 

 between it and extensor pollicis. The extensor indicis passes over 

 the wrist in a separate synovial sheath, but in the same groove 

 with extensor communis digitorum, and to its inner side. The 

 tendon passes obliquely to the inner side of the manus, crossing 

 the tendon of extensor carpi radialis. It then spreads out, and 

 is inserted iato the inner (radial) side and front surface of the 

 1st phalanx of the 2d digit. An expansion connects this tendon 

 with that of extensor pollicis, close to their insertion. 



C. and L.— 274-5 ; 276^7 ; 284, fig. 1 (e^). Shown as con- 

 nected with the inner side of the tendon of extensor communis 

 digitorum, not with extensor pollicis. 



