THE TARSO- METATARSAL 277 



Tlio arteries for the tarso-metatarsal joints are derived: (1) for the internal, 

 from the dorsahs pedis and internal plantar; (2; for the rest, twigs from the meta- 

 tarsal and deep plantar arches. 



The nerve-supply comes from the anterior tibial and plantar nerves. 



The movements permitted at these joints are flexion and extension of the 

 metatarsus on the tarsus; and at the inner and outer divisions, slight addtiction and 

 abduction. In the outer, the lateral motion is freer than in the inner joint, and 

 freest between the fifth metatarsal bone and the cuboid. In the inner joint, flexion 

 is combined with slight abduction, and extension with adduction. 



There is also a little gliding, which allows the transverse arch to be increased 

 or diminished in depth ; the inner and outer two bones sliding downwards, and the 

 two middle a little upwards, when the arch is increased; and vice verm when the 

 arch is flattened. 



(a) The Internal Tarso-metatarsal .Joint 

 Class. — Diarthrosis. Subdivision. — Arthrodia. 



A complete capsular ligament unites the first metatarsal with the internal 

 cuneiform, the fibres of which are very thick on the under and inner aspects; 

 those on the outer side pass from behind forAvards in the interval between the 

 interosseous ligaments which connect the two bones forming this joint with the 

 second metatarsal. The ligament on the plantar aspect is by far the strongest, and 

 blends at the cuneiform bone with the scapho-cuneiform ligament. 



(b) The Middle Tarso-metatarsal Joint 

 Class. — Diarthrosis. Subdivision. — Arthrodia. 



Into tins union there enter the three cuneiform and second and third metatarsal 

 Ijones, which are bound together by the following ligaments: dorsal, plantar, inter- 

 osseous. 



The dorsal ligaments. — 1. Some short fibres cross obliquely from the outer 

 edge of the internal cuneiform bone to the inner border of the base of the second 

 metatarsal bone; they take the place of a dorsal metatarsal ligament wliich is 

 wanting between the first and second metatarsal bones. 



2. Between the middle cuneiform and the base of the second metatarsal bone 

 some fibres run directly forwards. 



3. The external cuneiform is connected with (1) the outer corner of the second 

 metatarsal bone by a narrow band passing obliquely inwards ; (2) with the third 

 metatarsal by fibres passing directly forwards ; and (3) with the fourth metatarsal 

 l)y a short band passing obli(|uely outwards to the inner edge of its base. 



The plantar ligaments. — A strong ligament unites the internal cuneiform and 

 the bases of the second and third metatarsal bones. The tibialis -posticus is 

 inserted into these bones close beside it. Other slender ligaments connect the 

 middle cuneiform Avith the second, and the external cuneiform with the third 

 metatarsal Ijones. 



The interosseous ligaments. — (1) A strong broad interosseous ligament 

 extends between the outer surface of the internal cuneiform, and the inner surface 

 of the base of the second metatarsal bone. It is attached to both bones below 

 and in front of the articular facets, and separates the middle from the internal 

 tarso-metatarsal joint. (2) A second band is attached behind to a fossa on the 

 anterior and outer edge of the external cuneiform and to the interosseous ligament 

 between it and the cuboid, and passes horizontally forwards to be attached to the 

 whole depth of the fourth metatarsal bone behind its internal lateral facet, and to 

 the opposed surfaces of the third and fcnirth below their lateral articular facets. It 

 separates the middle tarso-metatarsal, and intermetatarsal between the third and 

 fourth bones, from the cubo-metatarsal joint. It is more firmly connected with the 

 third bone than with the fourth. (3) A slender ligament composed only of a few- 

 fibres often passes from a small tubercle on the inner and anterior edge of the 



