338 INFERIOR EXTREMITY 



which pass between the non-articular portions of the basal 

 parts of the bones, and they constitute the chief bonds of 

 union. 



In addition to these basal ligaments, the strong transverse 

 metatarsal ligament of the heads of the metatarsal bones unites 

 the distal extremities of the bones together. This ligament 

 has been previously described (p. 305). 



Joint Cavities of the Foot. There are six separate 

 joint cavities in connection with the tarsal, tarso-meta- 

 tarsal, and intermetatarsal articulations, viz. (i) the cavity 

 between the posterior facets of the talus and calcaneus ; 

 (2) the calcaneo-cuboid joint cavity; (3) the cavity of the 

 joint formed by the head of the talus, the navicular, the sus- 

 tentaculum tali, and the two calcaneo-navicular ligaments ; (4) 

 a complicated cavity which extends between the navicula- 

 cuneiform articulation, and is prolonged forwards between the 

 cuneiforms, and also between the cuboid and lateral cuneiform 

 bones. This cavity, however, is not confined to the tarsus, 

 but is continuous with the cavity between the second and 

 third metatarsal bones and the tarsus, as well as with the 

 cavities of the joints between the bases of the second, third, 

 and fourth metatarsal bones ; x (5) a separate cavity lies between 

 the first metatarsal and the medial cuneiform ; (6) a distinct 

 cavity for the articulations between the cuboid and the 'two 

 lateral metatarsal bones. This is prolonged distally into the 

 joint between the bases of these two metatarsals. 



Metatarso-phalangeal and Digital Joints. These joints 

 are constructed upon a plan almost identical with that 

 of the corresponding joints of the upper extremity. For the 

 detailed description the student is therefore referred to p. 

 163. In the metatarso-phalangeal joint of the great toe the 

 thick plantar accessory ligament or fibrous plate holds two large 

 sesamoid bones, which slide upon grooved surfaces on the 

 head of the metatarsal bone. 



Movements. The movements which take place in the tarso-metatarsal, 

 intermetatarsal, and in the majority of the tarsal joints, are of a gliding 

 character. In the joints between the talus and navicular, and also 

 between the calcaneus and the cuboid, movements of a wider range are 



1 The lateral interosseous tarso-metatarsal ligament, which passes from 

 the lateral cuneiform bone (frequently from the cuboid 'bone) to the base of 

 the fourth metatarsal bone, separates the cavity between the fourth and fifth 

 metatarsal bones and the cuboid from the general tarsal articular cavity. 



