102 



CALCANEUS. 



a constriction somewhat resembling a neck ; and the posterior ex- 

 tremity is narrow, and marked by a deep groove, for the tendon of the 

 flexor longus pollicis. 



Hold the astragalus with the broad articular surface upwards, and 

 the rounded head forwards ; the triangular lateral articular surface 

 will point to the side to which the bone belongs. 



Articulations. With four bones ; tibia, fibula, calcaneus, and sca- 

 phoid. 



Fig. 45.*. 



The CALCANEUS (os calcis) may be known by its large size and 

 oblong figure, by the large and 

 irregular portion which forms the 

 heel, and by two articular surfaces, 

 separated by a broad groove upon 

 its upper side. 



The calcaneus is divisible into 

 four surfaces, superior, inferior, ex- 

 ternal, and internal ; and two ex- 

 tremities, anterior and posterior. 

 The superior surface is convex be- 

 hind and irregularly concave in front, 

 where it presents two, and some- 

 times three articular facets, divided 

 by a broad and shallow groove (sul- 

 cus calcanei), for the interosseous li- 

 gament. The inferior surface is con- 

 vex and rough, and bounded poste- 

 riorly by the two inferior tuberosi- 

 ties, of which the internal is broad 

 and large, and the external smaller 

 and prominent. The external sur- 

 face is convex and subcutaneous, 

 and marked towards its anterior 

 third by two grooves, often sepa- 

 rated by a tubercle, for the tendons 

 of the peroneus longus and brevis. 

 The internal surface is concave 

 and grooved, for the tendons and 

 vessels which pass into the sole of 

 the foot. At the anterior extremi- 

 ty of this surface is a projecting pro- 



* The dorsal surface of the left foot. 1. The astragalus ; its superior qua- 

 drilateral articular surface. 2. The anterior extremity of the astragalus, which 

 articulates with (4) the scaphoid bone. 3. The calcaneus. 4. The scaphoid 

 bone. 5. The internal cuneiform bone. 6. The middle cuneiform bone. 7. 

 The external cuneiform bone. 8. The cuboid bone. 9. The metatarsal bones 

 of the first and second toes. 10. The first phalanx of the great toe 11. The 

 second phalanx of the great toe. 12. The first phalanx of the second toe. 13. 

 Its second phalanx. 14. Its third phalanx. 



