302 THE ARTICULATIONS OR JOINTS. 
with the tarsal articulations, viz.: (1) talo-calcaneal ; (2) talo-calcaneo-navicularis ; 
(5) caleaneo-cuboid; (4) scapho-cuneiform and its extensions; (5) occasionally 
cubo-cuneiform. 
TARSO-METATARSAL JOINTS. 
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, an inner, middle, and outer. 
(1) The inner tarso-metatarsal articulation occurs between the distal convex 
reniform surface of the internal cuneiform bone and the concavo-reniform surface 
on the proximal aspect of the base of the first metatarsal bone. 
Ligaments which form a capsule (Figs. 228 and 230) surround the articulation. 
In the capsule the dorsal and plantar tarso-metatarsal bands are its strongest parts, 
but it is not deficient either on the inner or on the outer aspects. 
A separate synovial membrane lines the capsule. 
(2) The middle 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 tarsak 
and its metatarsal aspects. Thus, on its tarsal side, the inner and the outer cunei- 
form bones project in front of the middle cuneiform, so that the latter only presents 
a distal surface to the articulation; while the internal cuneiform presents. a portion 
of its external surface, and the external cuneiform presents both its distal and 
portions of its outer and inner surfaces, since it projects in front of the ewboid 
bone. On its metatarsal side the base of the second metatarsal bome: fits into the: 
indentation between the outer and inner cuneiforms, to which it presents external 
and internal articular facets, but its proximal facet rests upon the distal facet of the 
middle cuneiform. The base of the third metatarsal bone rests its proximal facet 
upon the outer cuneiform. The fourth metatarsal base presents part of its internal 
facet to the external side of the outer cuneiform. In this way the indentations: 
alternate on the two sides of the articulation, and an extremely powerful interlock- 
ing of parts is provided, which places any marked independent movement of these: 
metatarsal bones entirely out of the question. 
The dorsal tarso-metatarsal ligaments (Fig. 229) are broad flat bands whieh 
represent the most distinct parts of an investing capsule. They pass from: behindl 
forwards, and while the second metatarsal bone receives three, 7.e. one from eachi 
cuneiform, the third metatarsal only receives one—from the external cuneifornn. 
The plantar tarso-metatarsal ligaments (Fig. 230) eorrespond with the foregoing 
in their general arrangement, but they are weaker. That for the second metatarsal 
is the strongest. Oblique bands extend from the inner cuneiform bone to the: 
second and third metatarsals. 
The interosseous cuneo-metatarsal ligaments are three in number. The ¢nne7 
connects the outer side of the internal cuneiform with the inner side of the base of 
the second metatarsal bone. The middle connects the inner side of the external 
cuneiform with the outer side of the base of the second metatarsal. The outer 
connects the adjacent outer sides of the external cuneiform and third metatarsal. 
The synovial membrane, which lines this articulation, sends a prolongation back- 
wards between the inner and middle cuneiform bones, where it opens into the 
scapho-cuneiform joint. It is likewise prolonged forwards upon both sides of each 
of the bases of the second and third metatarsal bones. 
(5) The external 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 investing capsule may be resolved into the following ligaments :— 
The dorsal tarso-metatarsal ligaments (Fig. 229) resemble those already described. 
The base of the fourth metatarsal receives one from the external cuneiform and one 
from the cuboid. The base of the fifth metatarsal receives one from the cuboid. 
The plantar tarso-metatarsal ligaments (Fig. 230) are the weakest bands of the 
