648 DISSECTION OF THE LEG. 



Dissection. The calcaneo-cuboid joint may be opened to see the articu- 

 lar surfaces: and the student is to keep in mind that all the other articula- 

 tions of the foot are to be opened for the like purpose, even should directions 

 not be given. 



ARTICULATIONS OF THE SCAPHOID BONE. The scaphoid bone articu- 

 lates in front with the three cuneiform bones, and laterally with the os 

 cuboides. 



In the articulation with the cuneiform bones (fig. 223) there are three 

 longitudinal dorsal ligaments (i, &, /), one to each bone ; but the inner- 

 most is the strongest and widest, and extends round the inside of the 

 articulation into the sole of the foot (fig. 225, e). 



The place of plantar bands is supplied by processes of the tendon of 

 the tibialis posticus. 



A synovial membrane (common of the tarsus) lines the articulation, 

 and sends forwards prolongation between the cuneiform bones. 



In the articulation with the os cuboides there is a dorsal oblique band of 

 fibres (fig. 223, h~) between the contiguous surfaces of the bones ; a plantar 

 transverse band (fig. 225, ef), which is concealed by the tendon of the 

 tibialis posticus ; and a strong interosseous ligament. 



Where the bones touch, the surfaces are tipped with cartilage, and are 

 furnished with a prolongation from the common synovial membrane of the 

 tarsus. 



ARTICULATOIXS OF THE CUNEIFORM BONES. These bones are united 

 to one another by cross bands ; and the external one articulates with the 

 os cuboides after a similar manner. 



The three cuneiform bones are connected together by short transverse 

 dorsal bands (fig. 223, n) between the upper surfaces. Similar plantar 

 ligaments are wanting, except one between the two innermost (fig. 225,/). 

 There are also interosseous ligaments between the contiguous surfaces of 

 the bones. Laterally there are articular surfaces between the bones, with 

 offsets of the common synovial membrane. 



Where the external cuneiform touches the cuboid bone the surfaces are 

 covered with cartilage. A dorsal ligament (fig. 223, n} passes transversely 

 between the two ; and a plantar ligament (fig. 225, g) takes a similar 

 direction. Between the bones there is also an interosseous ligament. 



This joint is furnished either with a distinct synovial sac, or with a 

 prolongation of the common tarsal synovial membrane. 



The synovial membrane of the articulations of the cuneiform bones is 

 common to many of the bones of the tarsus. Placed between the scaphoid 

 and the three cuneiforms it sends one prolongation forwards between the 

 inner and middle cuneiform to the joints witli the second and third in eta - 

 tarsal bones; another, outwards, to the articulation of the scaphoid with 

 the cuboid bone ; and sometimes a third to the joint between the external 

 cuneiform and the os cuboides. 



Articular surfaces. On the scaphoid are three articular faces, the 

 inner being rounded, and the other two flattened. The three cuneiforms 

 unite in a shallow elliptical hollow, which is most excavated internally. 



Movement. The cuneiform bones glide up and out on the scaphoid in 

 inversion of the foot, and down and in in eversion ; and the inner one 

 moves more than the others in consequence of the shape of the articular 

 surfaces, and the attachment to it of the tibialis anticus. 



When the bones pass down the dorsal ligaments are made tight: and 



