756 MAMMALIAN ANATOMY 



the cuboid on the fibular surface by a rough triangle. It is slightly 

 concave from side to side, and convex from above downward, and artic- 

 ulates with the proximal surface of the ectocuneiform. 



The second facet lies along the tibial margin below the facet for the 

 ectocuneiform. It is vertically oval, and slightly convex, and articu- 

 lates with the proximal end of the mesocuneiform. 



The third facet lies also on the tibial border, just below the pre- 

 ceding, from which it is separated by an elevated line. It is small, 

 nearly round, and convex in both directions ; it faces toward the 

 plantar aspect as well as distally, and articulates with the proximal 

 surface of the entocuneiform. 



Nomenclature. The scaphoid is often known as the navicular. 

 Both terms are inflections of the Greek and Latin words meaning a 

 boat, whence our words skiff and navy. The Germans call it das 

 Kahnbein, and the French le scapho'ide. 



Determination. The scaphoid is easily recognized by its shape 

 and by the presence of the tuberosity. If the smooth dorsal surface 

 be held upward, and the irregular distal surface toward the student, 

 the tuberosity will be on the side to which the bone belongs. 



Articulation. The scaphoid articulates on the proximal side with 

 the astragalus and slightly with the calcaneum, on the distal side with 

 the cuneiforms, and on the fibular side with the cuboid. 



Ossification. The scaphoid is developed from a single centre of 



ossification. 



THE ENTOCUNEIFORM. 



General Description. With the exception of the mesocunei- 

 form, the Entocuneiform is the smallest bone of the tarsus. It lies 

 distal to the scaphoid, proximal to the rudimentary first metatarsal, 

 and on the tibial and plantar sides of the mesocuneiform and the base 

 of the second metatarsal (Fig. 571). It is an elongated, flat bone, 

 twice as long as it is wide. When the tarsus is seen squarely from the 

 front or dorsal side, only a narrow strip of the entocuneiform is visible 

 as the tibial edge. It presents five surfaces, the dorso-tibial, the 

 plantar, the fibular, the proximal, and the distal. 



The dorso-tibial surface (Fig. 561) is the only one which is visible 

 on the back and inner side of the tarsus. The proximal part of its 

 dorsal margin is oblique, meeting the distal straight part in an obtuse 

 angle ; the proximal and distal margins are straight and nearly parallel, 



