PELVIC LIMBS 



753 



FIG. 568. 



tibial side of the cuboid. It may be recognized by its shape, which is 

 wholly different from that of any of the carpal or other tarsal bones. 

 It is flat and rectangular ; its vertical or dorso- 

 plantar diameter is one-fifth larger than the trans- 

 verse or tibio-fibular; its greatest length, between 

 the proximal and distal borders, is only one-half 

 the length of the dorso-plantar diameter. The 

 tibio-plantar angle of the proximal surface is pro- 

 duced into a prominent blunt process called the 

 tuberosity. The scaphoid has the six surfaces 

 common to tarsal bones. 



The proximal surface may be recognized at 

 once by its deep cup shape. Its general outline 

 is oblong, the tibio-fibular diameter being about 

 one-fourth less than the dorso-plantar. Its dorsal 

 margin is arcuate, and passes into the tibial and 

 fibular margins; the tibial border is slightly emar- 

 ginate, and directed somewhat toward the tibial 

 side for its dorsal half; it then becomes arcuate, 

 and is continued in a tibial, plantar, and proxi- 

 mal direction as the tibial margin of the tuber- 

 osity. The outer or fibular border is emarginate 

 and forms a rounded angle with the plantar 

 border. Near the angle and partly on the fib- 

 ular surface (Fig. 569) is a small convex facet, 

 which faces proximally and to the fibular side, 

 and articulates with a concavity on the tibial 



*/ 



margin of the distal end or greater process of 

 the calcaneum. The plantar border runs from this angle to the root 

 of the tuberosity, where it may be said to end, since the plantar margin 

 of the tuberosity, which is continuous on the inside with the tibial 

 margin, runs dorsally, distally, and to the fibular side, and is lost in 

 the lower plantar part of the proximal surface proper. 



The proximal surface presents three more or less distinct parts. 

 The largest is the oblong, concave, cup-shaped facet for the distal end 

 of the head of the astragalus. It occupies nearly all the surface 

 except the plantar third. The region around the tibio-plantar angle 

 is the dorso-fibular surface of the tuberosity, and lies in a different 



48 



POSITION OF SCAPHOID. 



