22(5 



Eversion. 



Condition of 

 foot in 

 standing ; 



effect of 

 inversion. 



Astragalus 

 with 



navicular 

 bone: 



dorsal 

 ligament. 



To lay bare 

 the cal- 

 caneo-navi- 

 cular liga- 

 ments. 



Internal and 



external 

 ligament. 



Synovial 

 sac. 



Surfaces of 

 bone. 



DISSECTION OF THE LE(J. 



and the arch increased ; the toes are moved inwards ; and the outer 

 border of the foot sinks, turning the sole in. 

 In eversion the above movements are reversed. 

 In the ordinary mode of standing the foot is everted to the 1 

 utmost, or nearly so, by the weight of the body ; if then inversion 

 is practised, the inner side of the foot is raised from the ground, 

 and the part is supported on its outer edge. 



ASTRAGALUS WITH THE NAVICULAR BONE. The head of the 

 astragalus is received into the hollow of the navicular bone, and is 

 united to it by a dorsal ligament ; but the place of plantar and 



lateral ligaments is supplied by strong 

 bands between the os calcis and the 

 navicular bone. 



The astragalo - navicular ligament 

 (fig. 87, d) is attached to the astra- 

 galus close to the articulation, and to 

 the dorsal surface of the navicular 

 bone : its attachments will be better 

 seen when it is cut through. 



Dissection. The external ligament 

 of the articulation may be seen on the 

 dorsum of the foot in the hollow 

 between the os calcis and the navi- 

 cular bone, and if the tendon of 

 the tibialis posticus be removed, the 

 internal ligament will be exposed, 

 covering the head of the astragalus 

 on the inner side and below. 



The internal or inferior calcaneo- 

 navicular ligament (fig. 89, c, p. 227) 

 is attached behind to the inner and 

 fore parts of the sustentaculum tali of 

 the os calcis, and in front to the inner 

 extremity and lower border of the 

 navicular bone. This ligament is 

 partly fibro- cartilaginous ; its inner 

 side is crossed by the tendon of the 



tibialis posticus muscle ; and its deep surface forms part of the 

 socket for the head of the astragalus. 



The eternal calcaneo-navicular ligament (fig. 87, e) is placed 

 outside the head of the astragalus, and is about three-quarters of an 

 inch deep. Behind, it is fixed to the upper part of the os calcis, 

 between the articular surfaces for the cuboid bone and astragalus ; 

 and in front it is inserted into the outer side of the navicular bone. 

 The synovial cavity of this articulation is continued backwards 

 into the joint between the front of the os calcis and the astragalus. 

 Articular surfaces. The head of the astragalus has three convex 

 articular surfaces, a large one in front, elongated transversely and 

 broader externally than internally, for the navicular bone ; a narrow 

 oblique surface below for the os calcis ; and a small intermediate 



FIG. 88. PLANTAR LIGAMENTS 

 OF THE FOOT (BOURGERY). 



1. Long plantar ligament. 



2. Inner part of the short 

 plantar ligament. 



3. Tendon of the peroneus 

 longus muscle. 



