REGIONAL ANATOMY 21 
Action.—This muscle flexes the second phalanx on the 
first, the first on the metacarpus, and the entire foot on the 
forearm. Mechanically, it acts as a stay when the animal 
is standing by maintaining the metacarpo-phalangeal angle. 
Tse Fuexor Prpis PERFoRANS, oR THE DEEP FLEXOR OF 
THE Puanances.—This muscle consists of three easily- 
divided portions: an ulnar, a humeral, and a radial, and has 
Fic. 18.—MeEp1an Section oF Foot. 
A, Os suffraginis ; B, os corone ; C, os pedis: D, navicular bone; ZH, tendon 
of the extensor pedis; F, insertion of the extensor pedis into the 
pyramidal process of the os pedis ; G, the tendon of the flexor perforatus ; 
H, insertion of perforatus into the os corone; J, tendon of the flexor 
perforans; J, its passing attachment to the os corone; KX, its final 
insertion into the semilunar crest of os pedis; a, section of coronary 
cushion ; 4, section of plantar cushion ; c, semilunar sinus of os pedis. 
for points of origin the olecranon process of the ulna, the 
inner condyloid ridge of the humerus, and the posterior sur- 
face of the radius. These portions are continued by a common 
tendon which enters the carpal sheath with the tendon of 
the perforatus, and continues with it through the synovial 
