434 THE INFERIOR EXTREMITY 



by a small facet on the medial surface of the cuboid as 

 well. The articular surface of the navicular is divided by 

 prominent ridges into areas or facets corresponding with the 

 different parts of the socket in which it lies. The synovial 

 stratum, which lines this joint, is prolonged forwards into the 

 intercuneiform joints. 



Cubo-navicular and Cubo-cuneiform Articulations. It has 

 been noted that the anterior pillar of the longitudinal arch of 

 the foot consists of a lateral and a medial column. The 

 tarsal portions of these are connected together by the cubo- 

 navicular and the cubo-cuneiform articulations. 



It is only occasionally that the navicular touches and 

 articulates directly with the medial surface of the cuboid. 

 When it does so, the facet on the cuboid lies in series 

 with the articular surfaces on the posterior ends of the cunei- 

 form bones, and forms with them the socket for the anterior 

 surface of the navicular. The ligaments which bind the 

 navicular to the cuboid are disposed transversely, and 

 consist of (i) a series of short strong interosseous fibres 

 which bind the opposed surfaces together ; (2) a dorsal band ; 

 and (3) a plantar band. 



The dorsal band has previously .been divided in exposing 

 the interior of the cuneo-navicular joint and in defining the 

 lateral calcaneo-navicular ligament, but the interosseous and 

 plantar ligaments may be readily displayed. 



The cuboid, by an oval facet on its medial surface, 

 articulates with the third cuneiform bone, forming thereby 

 the cubo-cuneiform joint. The two bones are bound together 

 by interosseous, dorsal, and plantar ligaments. By dividing 

 the dorsal ligament and insinuating the knife between the 

 two bones the interosseous ligament may be detected. It is 

 the strongest of the three ligaments. 



The synovial layer which lines the cuneo-navicular articula- 

 tion is prolonged into the cubo-cuneiform joint and also 

 into the naviculo-cuboid joint, when that exists. 



Tarso-metatarsal Articulations. The bases of the five 

 metatarsal bones articulate with the three cuneiform bones 

 and the cuboid bone, and are very firmly attached to them 

 by dorsal, plantar, and interosseous ligaments. It is particu- 

 larly important to note that the line of articulation is irregular, 

 and that the base of the second metatarsal bone is wedged 

 between the first and third cuneiform bones. 



