ARTICULATIONS 329 



The distal part of the posterior ligament forms a strong 

 narrow band of yellowish fibres, which takes a transverse 

 course on the back of the joint and is firmly attached to 

 both tibia and fibula, filling up the interval between them. 

 It constitutes a part of the tibio-fibular socket for the 

 talus at the ankle-joint (Figs. 120 and 121); and on the 

 proximal aspect of the articular surface of the talus, the 

 area over which it plays is usually easily distinguished. This 

 portion of the posterior ligament is called the inferior trans- 

 verse ligament. 



Dissection. To see the interosseous ligament of the tibio-fibular syndes- 

 mosis the bones of the leg may be sawn through about two inches proximal 

 to the distal end of the tibia, and then divided with the saw from above 

 downwards in a vertical-transverse, or frontal direction. This cut should 

 be planned so as to pass through the inferior tibio-fibular joint. The short 

 strong fibres of the interosseous ligament will then be seen, and also the 

 short narrow articular interval between the lower portions of the opposing 

 surfaces of the bones when the latter is present. If a cavity is present in 

 the distal part of the joint the synovial membrane of the capsule of the 

 ankle-joint is prolonged proximally over the inner surface of those parts of 

 the ligaments of the tibio-fibular syndesmosis which help to form the 

 boundaries of the cavity. 



ARTICULATIONS OF THE FOOT. 



The articulations of the foot are very numerous. They 

 consist of: 



1. Articulationes intertarsse, tarsometatarsce, and intermetatarsse. 



2. Articulationes metatarso-phalangeae. 



3. Articulationes digitorum pedis. 



The bones which enter into these articulations are the 

 seven tarsal bones, the metatarsal bones, and the phalanges. 

 The tarsal and metatarsal bones are bound together by inter- 

 osseous, plantar, and dorsal ligaments, and are disposed in the 

 form of two arches, viz. a longitudinal and a transverse. The 

 integrity of these arches is maintained: (i) partly by the 

 forms of the bones ; (2) partly by the tension of the liga- 

 ments ; (3) partly by supporting tendons ; and (4) partly by 

 the tension of the plantar aponeurosis. 



The longitudinal arch presents a greater height and a wider 

 span along the medial than along the lateral side of the foot. 

 The talus is placed on the summit of this arch and forms 

 its keystone. The posterior pillar of the longitudinal plantar 

 arch is short and solid, being formed by the calcaneus alone ; 

 the anterior pillar, much longer, is composed of several bones, 



