SCAPHOID AND CUNEIFORM BONES. 



125 



surface is a projecting process (sustentaculum tali), Fig. Gi * 



which supports the anterior articulating surface of the 

 astragalus, and serves as a pulley to the tendon of the 

 flexor longus digitorum. Upon the anterior extremity 

 is a flat articular surface, surmounted by a rough pro- 

 jection, which affords one of the guides to the surgeon 

 in the performance of Chopart's operation. The pos- 

 terior extremity is prominent and convex, and consti- 

 tutes the posterior tuber o sity ; it is smooth for the 

 upper half of its extent, where it corresponds with a 

 bursa; and rough below, for the insertion of the 

 tendo Achillis ; the lower part of this surface is bound- 

 ed by the two inferior tuberosities. 



Articulations. With two bones; the astragalus 

 and cuboid. In their articulated state a large oblique 

 canal is situated between the astragalus and calcaneus, 

 being formed by the apposition of the two grooves 

 sulcus tali and calcanei. This groove is called the 

 sinus tarsi, and serves to lodge a strong interosseous 

 ligament which binds the two bones together. 



Attachment of Muscles. To nine ; by the poste- 

 rior tuberosity, to the tendo Achillis and plantaris ; by the inferior tube- 

 rosities and under surface, to the abductor pollicis, abductor minimi 

 digiti, flexor brevis digitorum, flexor accessorius, and to the plantar fascia ; 

 and by the external surface, to the extensor brevis digitorum. 



The SCAPHOID bone may be distinguished by its boat-like figure, con- 

 cave on one side, and convex with three facets upon the other. It pre- 

 sents for examination an anterior and posterior surface, a superior and 

 inferior border, and two extremities, one broad, the other pointed and 

 thick. The anterior surface is convex, and divided into three facets, to 

 articulate with the three cuneiform bones ; and the posterior concave, to 

 articulate with the rounded head of the astragalus. The superior border 

 is convex and rough, and the inferior somewhat concave and irregular. 

 The external extremity is broad and rough, and the internal pointed and 

 prominent, so as to form a tuberosity. The external extremity sometimes 

 presents a facet of articulation with the cuboid. 



If the bone be held so that the convex surface with three facets look 

 forwards, and the convex border upwards, the broad extremity will point 

 to the side corresponding with the foot to which the bone belongs. 



Articulations. -^N \\hfour bones j astragalus and three cuneiform bones, 

 sometimes also with the cuboid. 



Attachment of Muscles. To the tendon of the tibialis posticus. 



The INTERNAL CUNEIFORM may be known by its irregular wedge-shape, 

 and by being larger than the two other bones bearing the same name. It 



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

 articular surface. 2. The anterior extremity of the, astragaltis, which articulates with 

 (4) the scaphoid bone. 3. The os galcis. 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\he great toe. 11. The second phalanx of the great toe. 12. The firs* 

 phalanx of the second toe. 13. Its second phalanx. 14. Its third phalaax, 



11* 



