DISSECTION OF THE ANTERIOR LIMB. 



33 



The Tendon of the Extensor Pedis (Plate 7). This tendon, after 

 throwing oflf the slip to the extensor suffraginis, descends over the front 

 of the metacarpus and digit, and lies on the middle line. Its play over 

 the anterior ligament of the 

 fetlock is facilitated by a 

 small synovial bursa; while, 

 over the front of the inter- 

 phalangeal joints, the synovial 

 membrane is directly sup- 

 ported by the deep face of 

 the tendon, there being no 

 anterior ligament for these 

 joints. At the middle of the 

 first phalanx the tendon is 

 joined on each side by a 

 strong band which descends 

 obliquely over the side of the 

 fetlock from the suspensory 

 ligament. The tendon is 

 finally inserted into the pyra- 

 midal process of the os pedis. 



Action. — The first action of 

 the muscle is to extend the 

 third phalanx on the second, 

 and then the second on the 

 first. When contraction is 

 continued it produces suc- 

 cessively extension of the 

 fetlock and of the carpus. 



Directions. — The tendons on 

 the back of the metacarpus 

 and digit must next be dis- 

 sected ; and, as a preliminary 

 step, the carpal and meta- 

 carpo-phalangeal sheaths 

 formed in connection with 

 these tendons should be ex- 

 amined. 



Dissection of the Metacarpus and Digit, showing the Tendons and their Synovial 



Sheaths (Chauveau). 

 1. Synovial bursa of the extensor metacarpi magnus ; 2. Superior cvl-de-sac, or pouch, of the 

 synovial membrane of the carpal sheath ; 21, 21 Inferior part of the same ; 3. Pouch of the radio- 

 carpal synovial membrane, appearing as a hernia between the posterior common ligament and the 

 outermost radio-carpal ligament ; 4. Synovial bursa of the extensor pedis ; 5. Protrusion of the 

 synovial membrane of the fetlock -joint; 6, 7, 8. Superior, middle, and inferior pouches of the 

 synovial membrane of the metacarpo-phalangeal sheath ; 9. Inferior extremity of the same, exposed 

 by the removal of the reinforcing sheath of the perforans tendon ; E. ^. Extensor suffraginis ; S. L. 

 Subcarpai ligament ; E. P. Extensor pedis ; S. S. Superior sesamoidean (suspensory) ligament ; F. 

 Pa. Flexor Perforans ; F. Pt. Flexor perforatus. 



D 



'k-^ 



Fig. 



