THE MUSCLES OF THE UPPER EXTREMITY. 139 



oberflachlichen Beugemiiskiilatur der Reptilien und Amphibien. ' 

 (Bronn's Klassendes Thier-Eeichs, vi. Band, pp. 278, 279.) 



It is a significant fact that neither Tiedemann nor 

 Prechtl, two very close observing anatomists, described 

 this muscle, nor had anything to say about it in their 

 works. 



82. Tlie Jiexor cUfjitorum profundus^ arises Heshy 

 by two strong heads from the proximal extremity of the 

 uhia. Between these heads the hrachialis anticus 

 muscle passes to be inserted upon the same bone. 



The radial head of the Jiexor digitorum profundus 

 comes off immediately in front of the articular humeral 

 facets and the tendon of the biceps, at about the middle 

 point on the shaft, while the remaining head arises from 

 the under side of the shaft as far over as tlie olecranon 

 process. These heads, as the fibres pass wristwards, 

 soon merge with each other, and the common muscle 

 thus formed is attached for some little distance to the 

 shaft of the ulna beneath it. After that, it rapidly con- 

 verges to a point, and near the middle of the shaft 

 becomes converted into its tendon. This passes to the 

 ulnar side of the carpus through the various fascia- 

 sheaths and fibrous loops there found, and once more 

 emerges below the first metacarpal. From this point 

 the strong tendon makes directly for the anterior aspect 

 of the superior margin of the proximal phalanx of the 

 index digit. Here it is again confined in a fibrous 



^ This muscle is designated also by this name in the works of 

 Selenka (Bronn's Klassen des Thier-Reichs, p. 136, No. 67), De Man, 

 Watson, and Carlsson ; likewise Gadow (foe. cit., p. 279) so defines 

 it for his muscle No. 91, presenting us with a synonymy of the same' 

 referring to the writers dating from Vicq d'Azyr, as well as with 

 a concise account bringing its history up to our present knowledge 

 of its anatomy in Aves. 



