18 WINGS OF BIRDS. 



the bases of the. cubital quills, and on the anterior side with the palmaris longus, 

 17, and is inserted by a short tendon into the projecting point of the ulnar car- 

 pal bone, analogous to the os pisiforme. Its action is to bend the hand, or 

 bring it back towards the fore-arm. 



17. The palmaris longus arises from the inner condyle of the humerus, imme- 

 diately above the flexor carpi ulnaris, 16, and covering the flexor carpi radialis, 

 19, runs superficially over the flexor digitorum, 18, and is inserted partly into the 

 base of the posterior carpal bone, partly into the fascia which covers the lower 

 surface of the metacarpus, partly into the ulnar carpal bone, and sends a slen r 

 der tendon along the radial metacarpal bone and the first phalanx, to be inserted 

 into the base of the second phalanx. Its action is to bend or adduct the hand, 

 and at the same time extend the digit. 



18. The flexor digitorum is a small muscle arising under the palmaris longus 

 from the inferior and posterior surface of the ulna, along four-fifths of its length, 

 the upper-fifth excepted. Its fibres pass obliquely forwards, and it sends off a 

 very long tendon, running anterior and parallel to that of the palmaris longus^ 

 and having a similar insertion. Another tendon also passes to be inserted into 

 the base of the radial metacarpal bone, under that of the supinator radii longus. 



19. The flexor carpi radialis arises from the inner condyle, immediately 

 below the origin of the pronator radii teres, 21, and concealed by the palmaris 

 longus, 17. Its fibres pass obliquely forwards along the lower and posterior 

 edge of the radius, in contact anteriorly with the pronator radii teres, and pos- 

 teriorly with the flexor digitorum, 18. It is inserted fleshy along the posterior 

 edge of the radius. Its action is to draw the arm obliquely downwards and' 

 forwards. 



20. Under these muscles is a shorter one, which arises from the posterior 

 edge and lower surface of the ulna, for two-thirds of its length, and forms a 

 short strong tendon, which passes over the wrist joint, to be inserted into the 

 base of the radial matacarpal bone. Its use is to assist in extending the hand. 



A thin fleshy muscle extends obliquely forwards from the outer edge of the 

 ulna in nearly its whole length, to be inserted along two-thirds of the lower sur- 

 face of the radius. It is a pronator of the radius, which, though fixed when the 

 wing is extended, has considerable motion when bent, in which case it tends to 

 elevate the hand. This muscle is analogous to the pronator radii quadratus. 



21. The most anterior muscle of those that come from the inner or posterior 

 part of the lower extremity of the humerus, is the pronator radii teres. It arises 

 from the upper part ef the inner condyle of the humerus, at a considerable dis- 

 tance up the arm, by a tendinous origin, passes obliquely outwards, in contact, 

 first, with the insertion of the biceps flexor cubiti, then, on the same or anterior 

 side of the fore-arm, with the extensor carpi radialis longior, 1 5, and on the • 

 other side with the flexor carpi radialis, 19; and is inserted into two-thirds of 



