THE BONES OF THE LOWER LIMB 



259 



bones. It is compressed from before backwards, and its long 

 axis is directed inwards and downwards. The anterior surface 

 presents a large convex articular surface, divided into three facets 

 by two ridges which converge inferiorly. The inner facet, for the 

 internal cuneiform, is pyriform, with the narrow end upwards. 

 The middle facet, for the middle cuneiform, is triangular, with the 

 truncated apex downwards. The outer facet, for the external cunei- 

 form, resembles the middle, except that it is rather shorter and has 

 a rounder apex. The posterior surface is characterized by a large 

 concave, pyriform facet for the front of the head oi the astragalus, 

 its narrow end being directed downwards and inwards. The 



Dorsal Surface 



Tuberosity. 



For External Cuneiforin._l| — 



Posterior Surface for 

 Head of Astragalus 



Spring Tubercle on 

 Plantar Surface 



For Middle Cuneiform 



_^For Internal Cuneiform 



Spring Tubercle 



Fig. 151. — The Right Navicular Bone. 

 A, Postero-superior View ; B, Antero-inferior View. 



dorsal surface, extensive and rough, is sloped downwards and 

 inwards. The plantar surface, narrow and rough, gives attachment 

 to the inferior calcaneo-navicular or ' spring ' ligament, and about 

 its centre there is usually a knob-like projection, called the spring 

 tubercle. The external surface is broad and rough, and it sometimes 

 presents a small facet for the cuboid, contiguous to the outer 

 facet on the anterior surface. The inner extremity (prow of the 

 boat) is inclined downwards, and forms a stout, round projection 

 on the inner side of the sole, called the tuberosity, which gives 

 insertion to the principal portion of the tendon of the tibialis 

 posticus. 



