TAKSO-METATAESAL JOINTS. 359 



ARTICULATIONES TARSOMETATARSE.E. 



The tarso-metatarsal joints are found between certain articular facets on the 

 cuboid and three cuneiform bones on the one hand, and others on the bases of the 

 five metatarsal bones. These articulations are associated with three distinct 

 synovial cavities namely, a medial, lateral, and intermediate. 



(1) The medial tarso-metatarsal articulation occurs between the anterior 

 convex reniform surface of the first cuneiform bone and the concavo-reniform surface 

 on the posterior aspect of the base of the first metatarsal bone. 



Ligaments which form the fibrous stratum of the articular capsule surround the 

 articulation. In the capsule the ligamenta tarsometatarsea dorsalia et plantaria 

 are its strongest parts, but it is not deficient either on the medial or on the lateral 

 aspects. 



A separate synovial stratum lines the fibrous stratum. 



(2) The intermediate tarso-metatarsal articulation is an elaborate joint. It 

 involves the three cuneiform bones and the bases of the second, third, and part of 

 the fourth metatarsal bones. 



The articulation presents the outline of an indented parapet both on its tarsal 

 and its metatarsal aspects. Thus, on its tarsal side, the first and the third cunei- 

 form bones project in front of the second cuneiform, so that the latter only presents 

 a distal surface to the articulation ; while the first cuneiform presents a portion of 

 its lateral surface, and the third cuneiform presents both its distal and portions of 

 its lateral and medial surfaces, since it projects in front of the cuboid bone. On its 

 metatarsal side the base of the second metatarsal bone fits into the indentation 

 between the third and first cuneiforms, to which it presents lateral and medial 

 articular facets, but its posterior facet rests upon the anterior facet of the second 

 cuneiform. The base of the third metatarsal bone rests its posterior facet upon the 

 third cuneiform. The fourth metatarsal base presents part of its medial facet to the 

 lateral side of the third cuneiform. In this way the indentations alternate on the 

 two sides of the articulation, and an extremely powerful interlocking of parts is 

 provided, which places any marked independent movement of these metatarsal bones 

 entirely out of the question. 



The ligamenta tarsometatarsea dorsalia are broad, flat bands which represent the 

 most distinct part of the fibrous stratum of an investing articular capsule. They 

 pass from behind forwards, and while the second metatarsal bone receives three, 

 i.e. one from each cuneiform, the third metatarsal only receives one from the third 

 cuneiform. 



The ligamenta tarsometatarsea plantaria correspond with the foregoing in their 

 general arrangement, but they are weaker. That for the second metatarsal is the 

 strongest. Oblique bands extend from the first cuneiform bone to the second and 

 third metatarsals. 



The ligamenta cuneometatarsea interossea are three in number. The medial 

 connects the lateral side of the first cuneiform with the medial side of the base of 

 the second metatarsal bone. The middle connects the medial side of the third 

 cuneiform with the lateral side of the base of the second metatarsal. The lateral 

 connects the adjacent lateral sides of the third cuneiform and third metatarsal. 



The stratum synoviale, which lines this articulation, sends a prolongation back- 

 wards between the first and second cuneiform bones, where it opens into the cuneo- 

 navicular joint. It is likewise prolonged forwards upon both sides of each of the 

 bases of the second and third metatarsal bones. 



(3) The lateral tarso-metatarsal articulation is found between the proximal 

 surfaces of the bases of the fourth and fifth metatarsal bones and the distal surface 

 of the cuboid. 



The fibrous stratum of the investing articular capsule may be resolved into the 

 following ligaments : 



The ligamenta tarsometatarsea dorsalia resemble those already described. The 

 base of the fourth metatarsal receives one from the third cuneiform and one from 

 the cuboid. The base of the fifth metatarsal receives one from the cuboid. 



