BONES OF THE FOOT. 



53 



innermost of which is sharp for the attachment of the interosseus mem- 

 brane. The shaft arches backwards, and gives attachment to 8 of the 12 

 muscles of the leg. 



Nutrient Canal, opens about the centre of the shaft posteriorly, its orifice 

 looking downwards. 



External Malleolusfi is the lower extremity of the bone. It is larger and 

 longer than the internal, articulates with the astragalus by a triangular 

 facet, and is grooved posteriorly for the tendons of the peroneus longus 

 and brevis muscles. Its edge affords attachment to the external lateral 

 ligament of the ankle-joint. 



THE FOOT. 



How are the bones of the Foot divided? Into the tarsus (7), meta- 

 tarsus (5), and phalanges (14). Total, 26 bones. 



Name the bones of the Tarsus. They are placed in 2 rows side by side, 

 2 bones in the external row, 5 in the internal, as follows- viz. 

 Internally, Astragalus.^ ScaphoidX 3 Cuneiform.?^ 



Externally, Os calcis. <? Cuboid.^ 



How many Articulations are in the Tarsus ? 28, each bone articulating 

 with 4 others, except the os calcis, which articulates 

 with 2, and the external cuneiform with 6 bones. 



What Peculiarities have the Tarsal Bones ? 

 They may be divided transversely at the astragalo- 

 scaphoid-calcaneo-cuboid articulation, the site of 

 Chopart's operation. 



The Astragalus,* has a rounded head, a convex 

 surface on which is a broad articular facet, and 

 on its inferior surface a deep groove between 

 2 articular facets. 



The Os Calcis f is a large bone, having on its upper 

 surface a deep groove for the interosseous liga- 

 ment, between 2 articular surfaces; anteriorly 

 a large irregular portion, the head; and pos- 

 teriorly an elongated portion forming the Heel. 

 On its internal surface is a projection, the Susten- 

 taculum Tali, which supports the internal articu- 

 lating surface ; below which process the bone is 

 deeply grooved for the plantar vessels and nerves 

 and the flexor tendons. To the os calcis are at- 

 tached 8 muscles and the plantar fascia. 

 5* 



