POSTERIOR ANTIBRACHIAL GROUP. 



2^9 



capsule of the navicular bone, termed the navicular sheath, forms 

 two cul-de-f^acs, one stretching upwards almost to the inferior 

 cul-de-sac of the sesamoid sheath, the other being situated under 

 the inferior navicular ligament. A broad strengthening sheath of 

 fibrous tissue covers the plantar aponeurosis and blends with it 

 inferiorly, being attached above by two bands to the sides of the 

 first phalanx. 



Action,— It flexes the joints below the carpus, and assists in 

 flexing the latter. 



Fig. 82. 



Longitudinal section through the digit of a Horse. 

 1, The skin ; 2, Extensor pedis tendon ; 3, Synovial cap- 

 sule of pastern joint ; 4, Metacarpus ; 5, Perforatus 

 tendon ; 6 (omitted in cut), Perforans tendon ; 7, Synovial 

 sheath ; 8, Projecting synovial cul-de-sac; 9, Inner aspect 

 of sesamoid bone ; 10, Tlie fetlock ; 11, The Y-ligament ; 

 12, The v-ligameut ; 13, Proximal phalanx ; 14, Terminal 

 portion of extensor tendon ; 15, Mesian phalanx ; 16, 

 Third sesamoid or navicular bone ; 17, The sensitive frog ; 

 18, Distal phalanx ; 19, The hoof ; 20, Sensitive laminae. 



ULNARIS ACCESSORIUS. 



{Flexor Accessorius Suhlimis.) 



(Fig. 81. c".) 



Situated on the posterior part of the fore-arm, between the 

 external and middle flexors of the metacarpus, it is triangular. 



