40 



HORSESHOEING. 



Fig. 24. 



The plantar cushion (Figs. 21, 22, 23) is composed almost 

 entirely of yellow elastic and white fibrous tissues, with adipose 

 (fat) cells distributed throughout their substance. It is similar 



in form to the horny frog, and 

 lies between it and the perforans 

 tendon (Fig. 24, a). The bulbs 

 are formed by the posterior 

 thicker portion which lies be- 

 tween the lateral cartilages and 

 is divided into two parts by the 

 cleft or median lacuna (Figs. 

 21, a, and 23, d). The summit 

 is attached to the plantar face 

 of the OS pedis in front of the 

 semilunar crest, and the bulbs 

 are attached to the lateral car- 

 tilages. It is covered inferiorly 

 by the velvety tissue of the frog 

 (pododerm). 



Right forefoot viewed from below, behind, 

 and the external side. This figure shows 

 clearly the position of the plantar cushion. 

 The external lateral cartilage and the tissues 

 covering the plantar cushion and under sur- 

 face of the OS pedis (velvety tissue of the sole 

 and fleshy frog) have been removed: a, fleshy 

 frog or plantar cushion; a', bulbs of plantar 

 cushion; the remaining visible parts belong to 

 the so-called "fleshy frog;" a", groove (median 

 lacuna) in the lower surface of the fleshy frog, 

 in which lies the frog-stay of the horny frog; 

 h, suspensory ligament of the plantar cushion 

 passing out of the bulbs; 6', small elastic cords 

 passing to the lateral cartilage; c, elastic liga- 

 ment coming from the lateral cartilage and 

 uniting with the suspensory ligament of the 

 plantar cushion; d, small tendinous cord be- 

 ginning in the skin behind the fetlock-joint 

 and ending on the os suffraginis in common 

 with 6 and e; e, tendinous reinforcing sheath of 

 the perforans tendon; /, reinforcing stay of the 

 perforatus tendon; g, perforatus tendon; h, 



perforans tendon; i, suspensory ligament of the fetlock; k, plantar surface of the os pedis, to 



which the plantar cushion is joined by fibrous bands. 



