INTERMETATARSAL JOINTS 



309 



continuous along the groove at the base of the fifth metatarsal bone with the dorsal ligament, 

 and as it passes round the lateral border of the foot it is somewhat thickened, and may be de- 

 scribed as the lateral cubo-metatarsal ligament. On its medial side it joins the interosseous 

 ligaments, thus completing the capsule below. It is not a thick structure, and to see it the long 

 plantar ligament, the peroneus longus, and lateral slip of the tibiahs posterior must be removed; 

 the attachment of these structures to the fourth and fifth metatarsal bones considerably assists 

 to unite them with the tarsus. 



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

 and forward from the cuboid to the bases of the fourth and fifth metatarsal bones. They com- 

 plete the capsule above, and are continuous laterally with the lateral cubo-metatarsal hgament. 



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

 joint. It is attached to the third cuneiform behind, and to the whole depth of the fourth meta- 

 tarsal behind its medial facet, and to the apposed surfaces of the third and fourth bones below 

 their articular facets. It is continuous below with the plantar ligament. 



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

 tinued between the fourth and fifth metatarsal bones. 



Relations.— The line of the tarso-metatarsal joints is crossed dorsally by the tendons of 

 the long and short extensor muscles of the toes and the tendon of the peroneus tertius. On 

 the plantar aspect it is in relation with the obhque adductor of the great toe, the short flexor 

 of the great toe, the lateral plantar artery, and the tendon of the peroneus longus. Its medial 

 end is subcutaneous except that it is crossed, near the plantar surface, by a slip of the tendon 

 of the tibialis anterior, and its lateral end is crossed by the tendon of the peroneus brevis. 



Fig. 337. — Section to show the Synovial Cavities of the Foot. 



1. Posterior talo-calcaneal. 

 4. Tarsal. 



2. Calcaneo-cuboid. 

 5. Cubo-metatarsal. 



3. Anterior talo-calcaneo-navicular. 

 6. First metatarso-cuneiform. 



7. THE INTERMETATARS.IL ARTICULATIONS 



Class. — Diarthrosis. 



Subdivision. — Arthrodia. 



The bases of the metatarsal bones are firmly held in position by dorsal, plantar, 

 and interosseous ligaments, supplementing the articular capsules. The first 

 occasionally articulates by means of a distinct facet with the second metatarsal 

 (figs. 245 and 246). 



The dorsal ligaments are broad, membranous bands passing between the four lateral toes 

 on their dorsal aspect; but in place of one between the first and second metatarsal bones, a 

 ligament extends from the first cuneiform to the base of the second metatarsal bone. 



The plantar ligaments are strong, thick, well-marked ligaments which connect the bones on 

 their plantar aspect. 



The interosseous ligaments are three in number, very strong, and are situated at the points 

 of union of the shaft with the bases of the bones, and fiU up the sulci on their sides. They limit 

 the synovial cavities in front of the synovial facets. 



The common synovial membrane of the tarsus extends between the second and third, and 

 third and fourth bones; that of the cubo-metatarsal joint extending between the fourth and fifth. 



The arterial and nerve-supply is the same as for the tarso-metatarsal joints. 



The movements consist merely of gliding, so as to allow the raising or widening^of the 

 transverse arch. Considerable flexibility and elasticity are thus given to the anterior part of 

 the foot, enabling it to become moulded to the irregularities of the ground. 



The Union of the Heads of the Metatarsal Bones 



The heads of the metatarsal bones are connected on their plantar aspect by 

 the transverse ligament [Ligg. capitulorum transversa], consisting of four bands 



