108 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM 



the os calcis, is a facet resting upon the inferior calcaneoscaphoid 

 ligament, the three forming one continuous surface. 



The posterior surface is small and narrow, and marked by 

 a groove for the flexor longus pollicis. Bounding the groove 

 are two tubercles, the external more prominent and giving 

 attachment to the posterior band of the external lateral liga- 

 ment. 



The Cuboid 



The cuboid (os cuboideum) is found on the lateral aspect 

 of the tarsus, between the os calcis and the fourth and fifth 

 metatarsal bones, external to the scaphoid and external cunei- 

 form bones. It is pyramidal in shape, its base directed inward 

 and its apex outward. It presents for examination six surfaces, 

 three non-articular dorsal, plantar, and external; three articular 

 posterior, anterior, internal. 



Articulations. The posterior surface with the os calcis, 

 the anterior surface (two facets) with the fourth and Jit'tii 

 metatarsal, the internal surface with the external cuneiform, 

 (occasionally) the scaphoid. 



Attachments of Muscles. Part of the flexor brevis hallucis 

 and a slip from the tendon of the tibialis posticus. It also 

 receives the attachments of several ligaments. 



Scaphoid or Navicular 



Is situated at the inner aspect of the tarsus, between the 

 astragalus and the three cuneiform bones. It presents for 

 examination anterior, posterior, dorsal, plantar, internal, and 

 external surfaces. 



Articulations. Astragalus and three cuneiform bones. 



Attachment of Muscle. Part of tibialis posticus. 



The Cuneiform 



The cuneiform bones are three in number internal, middle, 

 and external found between the scaphoid behind, the first, 

 second, and third (sometimes the fourth) metatarsal bones 

 in front, the cuboid externally. 



