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THE MUSCLES OF THE OX 



IV. MUSCLES OF THE FOREARM 

 A. Extensor Division 

 The extensor carpi radialis is like that of the horse. There is sometimes a 

 small muscle lying along its inner border, which may represent the extensores 

 pollicis. 



There are three digital extensors : 1. The common or anterior digital extensor 

 (M. extensor digitalis communis) arises by two heads from the extensor epicondyle 

 and the ulna. The heads fuse about the middle of the forearm, and terminate 

 soon on a tendon which passes over the carpus and metacarpus, gradually inclining 



Fit;. 215. — Right Carpus of Ox with BuRS-iE and Fig. 216. — Right Carpus of Ox with Burs/E and 

 Synovial, Sheaths Injected, Extern.\l View. Synovial Sheaths Injected, Internal, View. 



1, Extensor carpi radialis, with synovial sheath (V) and bursa {1")\ 2, extensor carpi obliquus, with synovial 

 sheath (2') and bursa {2") ; S, extensor digiti tertii proprius; 4, extensor digitalis communis; 3' , common synovial 

 sheath of 3 and 4\ 5, extensor digiti quarti proprius, with synovial sheath (5'); 6, 6' , flexor c^rpi externus, with 

 bursa (.6"); 7, flexor carpi interims, with synovial sheath; 8, deep digital flexor, with synovial sheath {8')\ 9, 

 flexor carpi medius; 10, superficial digital flexor, with synovial sheath 10'; a, radius; b, carpus; c, metacarpus; 

 d, cut edge of aninihir ligament. (After Sciimidtchen.) 



forward. At the fetlock joint it divides into two branches, which are inserted 

 into the third phalanges. 2. The internal digital extensor (M. extensor digiti 

 tertii proprius) arises on the extensor epicondyle, and is inserted by two branches 

 into the second and third phalanges of the inner digit. The tendon receives two 

 reinforcing slips from the suspensory ligament. 3. The lateral digital extensor 

 (M. extensor digitalis lateralis s. digiti quarti proprius) arises from the external 

 lateral ligament of the elbow joint, the external tuberosity of the radius, and the 

 ulna. The t(>ndon terminates like that of the preceding muscle. 



The extensor carpi obliquus r(>s(>nil)lcs that of the horse. 



The (>xt('iisor leiidoiis are bound down at the carpus by an annular ligament, 

 and are furnished with synovial sheaths (Figs. 215, 216). 



