THE CALCANEO-ASTRAGALOID JOINT. 445 



The plantar calcaneo-cuboid ligaments are the long and the short. The 

 former, known as the long plantar ligament (Fig. 461), arises from the perios- 

 teum of the under side of the calcaneum in front of the posterior tubercles, and runs 

 forward as a flat band, at first some two centimetres broad, to the whole length of 

 the ridge of the cuboid, except its inner end. It passes beyond this to the bases of 

 the outer three metatarsals in a somewhat broken and weak layer of fibres forming 

 a bridge over the groove for the tendon of the peroneus longus. The short 

 plantar ligament (Fig. 461) is in part hidden by the longer, but is seen at its 

 inner side. It arises from the anterior tubercle of the calcaneum and the bone in 

 front of it and goes to the under side of the cuboid, between the posterior border 

 and the ridge. The inner fibres run obliquely forward and inward. 



The inferior calcaneo-scaphoid ligament (Fig. 460) fills the gap on the 

 plantar side of the foot between the sustentaculum and the scaphoid. It is more or 

 less divisible into two parts, which have a common origin from the anterior border 

 of the sustentaculum. The inner and stronger part runs obliquely forward and 

 inward to the lower border of the scaphoid near the tuberosity. The outer part 

 runs more nearly straight forward to the outer part of the same border. There is 

 generally a small interspace between them. The upper surface of the inner portion 

 of the ligament is covered by a coating of articular cartilage completing the joint 

 for the head of the astragalus. This cartilage is usually wanting at the anterior 

 outer angle of the space between the bones. Beneath and to the inner side of the 

 ligament runs the tendon of the tibialis posticus. On the inner side of the foot 

 this ligament is continuous with a part of the superior astragalo-scaphoid and with 

 the termination of the deltoid ligament. 



The inferior scapho-cuboid ligament (Fig. 461) is an insignificant group 

 of fibres. 



The inferior scapho-cuneiform ligaments (Fig. 461) are three distinct 

 bands, of which the inner is the broadest, the others being more cord-like, diverging 

 from the under side of the scaphoid to the three cuneiform bones. They are all 

 continuous with the fibres of the tendon of the tibialis posticus. 



On the plantar side there is a very irregular arrangement of fibres passing from 

 the tarsus to the metatarsus and a considerable system of oblique fibres running 

 inward and forward from the cuboid and the fifth metatarsal to the external cunei- 

 form and to the bases of several metatarsal bones. 



The joints of the phalanges are on the same plan as in the hand and require no 

 further description. The sesamoid bones at the tarso- metatarsal joint of the great 

 toe are very large and connected by the glenoid ligament. 



THE POSTERIOR CALCANEO-ASTRAGALOID JOINT. 



This joint (Fig. 460) is separated from the anterior by the interosseous ligament, 

 which is continuous with the capsule that completely surrounds the articulation. 

 This capsule is in most parts weak, but is strengthened behind by the posterior 

 astragalo-calcaneal ligament. 



THE ANTERIOR CALCANEO-SCAPHO-ASTRAGALOID JOINT. 



This articulation (Fig. 460) may be called a ball-and-socket joint, although the 

 head of the astragalus is not a part of the surface of a sphere. The articular surfaces 

 have been described with the bones. The socket is made by the anterior articular 

 facet or facets of the calcaneum, by the posterior facet of the scaphoid, by the inter- 

 osseous ligament joining these externally, and by the inferior calcaneo-scaphoid liga- 

 ment, with its cartilaginous plate, which fuses on the inner side with the superior 

 calcaneo-scaphoid and the deltoid ligament, all of which make a capsule around the 

 head, completed by the interosseous astragalo-calcaneal ligament. A fold of syno- 

 vial membrane,^ variously developed, which may contain fibrous tissue, is generally 

 found on the floor of this socket, extending back from the interruption of the anterior 

 facet on the calcaneum, or from a corresponding place when it is simple, to the inferior 



^ E. Barclay Smith : Journal of Anatomy and Physiology, vol. xxx., 1896. 



