342 



THE ARTICULATIONS, OR JOINTS 



The posterior inferior ligament (ligamentum malleoli lateralis posterius) (Fig. 

 277), smaller than the preceding, is disposed in a similar manner on the posterior 

 surface of the articulation. 



The inferior transverse ligament lies under cover of the posterior ligament, 

 and is a strong, thick band of yellowish fibres which passes transversely across 

 the back of the joint, from the external malleolus to the posterior border of 

 the articular surface of the tibia, almost as far as its malleolar process. This 

 ligament projects below the margin of the bones, and forms part of the articulating 

 surface for the astragalus. 



The inferior interosseous ligament (Fig. 275) consists of numerous short, strong, 

 fibrous bands which pass between the contiguous rough surfaces of the tibia and 

 fibula, and constitute the chief bond of union between the bones. This ligament 

 is continuous above with the interosseous membrane. 



Synovial Membrane. The synovial membrane lining the articular surface is derived from 

 that of the ankle-joint (Fig. 275). 



Movements. The movement permitted in these articulations is limited to a very slight 

 gliding of the articular surfaces one upon another. 



IV. The Tibiotarsal Articulation, or Ankle-joint (Articulatio Talocruralis) 



(Figs. 274, 275). 



The ankle is a ginglymus or hinge-joint. The bones entering into its forma- 

 tion are the lower extremity of the tibia and its malleolus and the external malleolus 

 of the fibula, which forms a mortise (Fig. 273) to receive the upper convex surface 



T ' arsometatarsal 

 articulations. 



Tarsal articulations. 



FIG. 274. Ankle-joint; tarsal and tarsometatarsal articulations. Internal view. Right side. 



of the astragalus and its two lateral facets. The bony surfaces are covered by 

 hyaline cartilage and interconnected by a capsule (capsula articularis), which in 

 places forms thickened bands constituting the following ligaments: 



Anterior. 

 Posterior. 



Internal Lateral. 

 External Lateral. 



