356 



SYNDESMOLOGY 



part of the articular cavity in which it is received. The dorsal surface of the 

 ligament presents a fibrocartilaginous facet, lined by the synovial membrane, 

 and upon this a portion of the head of the talus rests. Its plantar surface is 

 supported by the tendon of the Tibialis posterior ; its medial border is blended with 

 the forepart of the deltoid ligament of the ankle-joint. 



Tibialis 

 posterior 



Interosseous 



talocalcaneal 



ligament 



Lateral 

 talocalcaneal 



ligament 



Anterior 

 talocalcaneal 



ligament 



FIG. 359. Talocalcaneal and talocalcaneonavicular articulations exposed from above by removing the talus. 



The plantar calcaneonavicular ligament, by supporting the head of the talus, is principally 

 concerned in maintaining the arch of the foot. When it yields, the head of the talus is pressed 

 downward, medialward, and forward by the weight of the body, and the foot becomes flattened, 

 expanded, and turned lateralward, and exhibits the condition known as flat-foot. This ligament 

 contains a considerable amount of elastic fibers, so as to give elasticity to the arch and spring 

 to the foot; hence it is sometimes called the "spring" ligament. It is supported, on its plantar 

 surface, by the tendon of the Tibialis posterior, which spreads out at its insertion into a number 

 of fasciculi, to be attached to most of the tarsal and metatarsal bones. This prevents undue 

 stretching of the ligament, and is a protection against the occurrence of flat-foot; hence muscular 

 weakness is, in most cases, the primary cause of the deformity. 



Cuneonavicular Articulation (articulatio cuneonavicularis; articulation of the 

 navicular with the cuneiform bones'). The navicular is connected to the three 

 cuneiform bones by dorsal and plantar ligaments. 



The Dorsal Ligaments (ligamenta navicularicuneiformia dorsalia). The dorsal 

 ligaments are three small bundles, one attached to each of the cuneiform bones. 

 The bundle connecting the navicular with the first cuneiform is continuous around 

 the medial side of the articulation with the plantar ligament which unites these 

 two bones (Figs. 354, 355) . 



The Plantar Ligaments (ligamenta navicularicuneiformia plantaria) . The plantar 

 ligaments have a similar arrangement to the dorsal, and are strengthened by slips 

 from the tendon of the Tibialis posterior (Fig. 358). 



Synovial Membrane. The synovial membrane of these joints is part of the great tarsal synovial 

 membrane (Fig. 360). 



Movements. Mere gliding movements are permitted between the navicular and cuneiform 

 bones. 



Cuboideonavicular Articulation. The navicular bone is connected with the 

 cuboid by dorsal, plantar, and interosseous ligaments. 



