SCAPHOID. 103 



cess (sustentaculum tali,) 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 arti- 

 cular surface, surmounted by a rough projection, which affords one of 

 the guides to the surgeon in the performance of Chopart's operation. 

 The posterior extremity is prominent and convex, and constitutes the 

 posterior tuberosity ; it is smoooth 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 bounded 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 posterior tuberosity, to 

 the tendo Achillis and plantaris ; by the inferior tuberosities 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, 

 concave on one side, and convex with three facets upon the other. 

 It presents for examination an anterior and posterior surface, a supe- 

 rior 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 pos- 

 terior 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 



Articulations. With four bones; 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 presents for examination a convex and a concave sur- 

 face, a long and a short articular border, and a small and a large 

 extremity. 



Place the bone so that the small extremity may look upwards and 



