144 



Bones of the Lower Extremity. 



Os cnneiforme 1 



Os cnneiforme II 



for the os 

 > cuneiforme 



n 



for the os naviculare 



for the 

 os cunei- 

 forme III 



for the os navieulare 



for the 

 os cunei 

 forme II 



for the os naviculare 



192194. The three cuneiform bones of the right 

 side, ossa cunei f or mia pnmum, secundum, tertium, from behind. 



The ossa Cuneiform] a prim inn. secundum, tertium (wedge bonesj (see also 

 Figs. 198 203 and 271) are wedge-shaped; they lie distal from the os naviculare and are 

 numbered beginning at the medial border of the foot. 



The OS cuneiforme primum (0. T. internal cuneiform bone) is the largest with the 

 base of the wedge directed plantarward; it is curved slightly lateralward at its upper extremity. 

 The posterior surface is triangularly rounded, flat and covered with cartilage (for the os navi- 

 culare). The medial surface, turned also upward, is rough and possesses in front and below 

 an oblique flat groove in which lies the tendon of the m. tibialis anterior (see Fig. 1 99) being 

 separated from the bone by the bursa subtendinea m. tibialis anterioris. The anterior 

 surface is covered with cartilage, bean-shaped (for the os metatarsale I); the lateral surface 

 has an anterior, small articular surface (for the os metatarsale II) and a posterior (for the 

 os cuneiforme II). 



The os cuneiforme secundum is the smallest with the base of the wedge directed 

 dorsalward. The posterior triangular surface, covered with cartilage, serves for the attachment 

 of the os naviculare, the anterior surface, covered with cartilage, for the os metatarsale II; 

 on the medial and lateral surfaces are small articular surfaces for the neighboring cuneiform bones. 



The os cuneiforme tertium has the base of the wedge looking dorsalward. Its 

 posterior, rounded surface, covered with cartilage, is attached to the os naviculare, the anterior 

 to the os metatarsale III; medianward it possesses a small, anterior articular surface for the 

 os metatarsale II and a larger, posterior for the os cuneiforme II; lateralward it supports a 

 small articular surface for the os cuboideum. 



