278 



THE A H Tin LA TIONS 



external cimeiforin to a groove on tlie outer edge of tlie second metatarsal bone 

 between the two lateral facets. 



The synovial membrane is jirolonged forwards from that of the scapho-cunei- 

 form and inter-cuncifonn articulations. 



((•) The Cubo-metatarsal Joint 

 Class. — Dinrthrosis. Subdivision. — Arthrod'm. 



The bones comprising this joint are the fourth and fifth metatarsal, and the 

 anterior surface of the cul)oid, iirmly connected on all sides by 



Dorsal. 



Plantar. 



Interosseous ligaments. 



The plantar cubo-metatarsal ligament is a broad, Avell-marked ligament, 

 Avhich extends from tlic cuboid behind to the bases of tlie fourth and fifth meta- 



FiG. 258. — Section to show the Synovial Cavities of the Foot. 



1. Posterior calcanco-astragaloid. 

 4. Tarsal. 



2. Calcaneo-cuboid. 

 5. Cubo-metatarsal. 



3. Anterior calcaiieo-astragalo-scaphoid. 

 6. First metatarso-cuneiforin. 



tarsal bones in front. It is continuous along the groove at the base of tlie fifth 

 metatarsal bone ■v\nth the dorsal ligament, ancl as it passes round the outer border 

 of tlie foot it is somewhat thickened, and may be described as the external cubo- 

 metatarsal ligament. On its inner side it joins the interosseous ligaments, thus 

 (•om|ik'tiiig tlie cajjsule below. It is not a thick structure, and to see it the long 

 plantar ligament, the peroneus longus, and external slip of the tibialis posticus 

 must be removed; the attachment of these structures to the fourth and fifth meta- 

 tarsal bones considera})ly assists to unite them with the tarsus. 



The dorsal cubo-metatarsal ligament is composed of fibres which pass 

 o])liquely outwards and forwards from the cuboid to the bases of the fourth and 

 fifth metatarsal hones. They complete the cajisule above, and are continuous 

 externally with the external cubo-metatarsal ligament. 



The interosseous ligament shuts off the cubo-metatarsal from the middle tarso- 

 metatarsal joint. It is attached to the external cuneiform behind, and to the 

 whole depth of the fourth metatarsal Ix'hind its internal lateral facet, and to the 

 apposed surfaces of the third and fourth bones lielow their articular facets. It is 

 continuous Ijclow witli the ]ilaiitar ligament. 



The synovial membrane is separate from the other synovial sacs of the tarsus, 

 and is continued between the fourth and fifth metatarsal bones. 



