254 THE SKELETON. 



tudinallj, and often subdivided into two by an elevated ridge; of these the 

 posterior articulates with the lesser process of the os calcis ; the anterior, with 

 the upper surface of the calcaneo-scaphoid ligament. The internal surface pre. 

 sents at its upper part a pear-shaped articular facet for the inner malleolus, 

 continuous above with the trochlear surface ; below the articular surface is a 

 rough depression, for the attachment of the deep portion of the internal lateral 

 ligament. The external surface presents a large triangular facet, concave from 

 above downwards, for articulation with the external malleolus ; it is continuous 

 above with the trochlear surface ; and in front of it is a rough depression for 

 the attachment of the anterior fasciculus of the external lateral ligament. The 

 anterior surface, convex and rounded, forms the head of the astragalus ; it is 

 smooth, of an oval form, and directed obliquely inwards and downwards; it is 

 continuous below with that part of the anterior facet on the under surface which 

 rests upon the calcaneo-scaphoid ligament. The head is surrounded by a con- 

 stricted portion, the neck of the astragalus. The posterior surface is narrow, 

 and traversed by a groove, which runs obliquely downwards and inwards, and 

 transmits the tendon of the Flexor Longus Pollicis. 



To ascertain to which foot it belongs, hold the bone with the broad articular 

 surface upwards, and the rounded head forwards ; the lateral triangular articu- 

 lar surface for the external malleolus will then point to the side to which the 

 bone belongs. 



Articulations. With four bones : tibia, fibula, os calcis, and scaphoid. 



THE SCAPHOID. 



The Scaphoid or Navicular Bone, so called from its fancied resemblance to 

 a boat, is situated at the inner side of the tarsus, between the astragalus behind 

 and the three cuneiform bones in front. This bone may be distinguished by 

 its form, being concave behind, convex and subdivided into three facets in front. 



The anterior surface, of an oblong form, is convex from side to side, and sub- 

 divided by two ridges into three facets, for articulation with the three cunei- 

 form bones. The posterior surface is oval, concave, broader externally than 

 internally, and articulates with the rounded head of the astragalus. The supe- 

 rior surface is convex from side to side, and rough for the attachment of liga- 

 ments. The inferior is somewhat concave, irregular, and also rough for the 

 attachment of ligaments. The internal surface presents a rounded tubercular 

 eminence, the tuberosity of the scaphoid, which gives attachment to part of 

 the tendon of the Tibialis Posticus. The external surface is broad, rough, and 

 irregular, for the attachment of ligamentous fibres, and occasionally presents a 

 small facet for articulation with the cuboid bone. 



To ascertain to which foot it belongs, hold the bone with the concave arti- 

 cular surface backwards, and the convex dorsal surface upwards ; the broad 

 external surface -will point to the side to which the bone belongs. 



Articulations. With four bones : astragalus and three cuneiform ; occasion- 

 ally also with the cuboid. 



Attachment of Muscles. Part of the Tibialis Posticus. 



THE CUNEIFORM BONES. 



The Cuneiform Bones have received their name from their wedge-like shape. 

 They form with the cuboid the most anterior row of the tarsus, being placed 

 between the scaphoid behind, the three innermost metatarsal bones in front, 

 and the cuboid externally. .They are called the first, second^ and third, counting 

 from the inner to the outer side of the foot, and, from their position, internal, 

 middle, and external. 



The Internal Cuneiform is the largest of the three. It is situated at the 

 inner side of the foot, between the scaphoid behind and the base of the first 

 metatarsal in front. It may be distinguished from the other two by its large 



