754 MAMMALIAN ANATOMY 







plane ; it is slightly concave, and articulates with the tibial side of the 

 head of the astragalus. The region about the fibulo-plantar angle is 

 separated from the large facet by an oblique line, the continuation of 

 the plantar border of the tuberosity, dorsally and to the fibular side; the 

 region is rough for the attachment of the astragalo-scaphoid ligament. 



The dorsal surface is not so long as it is wide. It has its proximal 

 and distal borders sharp and parallel, diverging slightly on the tibial 

 side. Its fibular margin, although rounded, is well defined ; on the 

 tibial side the surface passes regularly into the tibial surface. It is 

 convex from side to side, slightly concave in the proximo-distal direc- 

 tion. It is smooth, and in some specimens gives origin to a part of 

 the extensor brevis digitorum muscle. 



FIG. 569. 



Dorsal Side. 



With Cuboid. 



Distal Side. \\J^L Proximal Side. 



With Calcaneum. f^m. 



//' ^wSP/MKsnfiL 



j -Tuberosity. 

 With Astragalus. 



Plantar Side. 



LEFT SCAPHOID, FIBULAR SURFACE. 



The tibial surface (Fig. 561) presents no articular facets; it is 

 oblong, slightly rough, and convex in both directions. The plantar 

 proximal part is produced into the tuberosity. Its proximal margin 

 is sharp and emarginate, with its plantar third bent nearly at right 

 angles to the dorsal part, limiting the proximal surface of the tuber- 

 osity. Its plantar margin is parallel with this part of the proximal 

 margin, forming also the tibial margin of the plantar surface of the 

 tuberosity. Its distal margin is well defined, and almost straight in a 

 dorso-plantar direction ; it is somewhat irregular, because it limits the 

 irregular facets on the distal surface. 



o 



The plantar surface (Fig. 587) is L-shaped, one branch of the L 

 running in a proximal direction and representing the plantar surface 

 of the tuberosity, the other branch passing transversely as the surface 

 of the bone itself. Its margins are all rounded, and it is convex for 

 the attachment of the plantar ligaments. 



