TARSAL ARTICULATIONS. 137 



bones of the foot. It is the division of this portion of these liga- 

 ments that demands the especial attention of the surgeon in per- 

 forming Chopart's operation. 



The plantar ligaments have the same disposition on the plantar 

 surface of the foot ; three of them, however, are of large size and 

 have especial names, viz. the 



Calcaneo-scaphoid, 

 Long calcaneo-cuboid, 

 Short calcaneo-cuboid. 



The inferior calcaneo-scaphoid ligament is a broad and fibro- 

 cartilaginous band of ligament, which passes for- 

 wards from the anterior and inner border of the os Fi S- 64.* 

 calcis to the edge of the scaphoid bone. In addition 

 to connecting the os . calcis and scaphoid, it sup- 

 ports the astragalus, and forms part of the cavity in 

 which its rounded head is received. It is lined 

 upon its upper surface by the synovial membrane of 

 the astragalo-scaphoid articulation. 



The firm connexion of the os calcis with the 

 scaphoid bone, and the feebleness of the astragalo- 

 scaphoid articulation are conditions favourable to 

 the occasional dislocation of the head of the astra- 

 galus. 



The long calcaneo-cuboid, or ligamentum longum jffi 



plantfB, is a long band of ligamentous fibres, which 

 proceeds from the under surface of the os calcis to the rough sur- 

 face on the under part of the cuboid bone, its fibres being continued 

 onwards to the bases of the third and fourth metatarsal bones. 



This ligament forms the inferior boundary of a canal in the 

 cuboid bone, through which the tendon of the peroneus longus 

 passes to its insertion into the base of the metatarsal bone of the 

 great toe. 



The short calcaneo-cuboid, or ligamentum breve plantce, is situated 

 nearer to the bones than the long plantar ligament, from which it 

 is separated by adipose tissue ; it is broad and extensive, and ties 

 the under surface of the os calcis and cuboid bone firmly together. 



The interosseous ligaments are five in number; they are short 

 and strong ligamentous fibres situated between adjoining bones, 

 and firmly attached to their rough surfaces. One of these, the 

 calcaneo-astragaloid, is lodged in the groove between the upper 

 surface of the os calcis, and the lower of the astragalus. It is 

 large and very strong, consists of vertical and oblique fibres, and 

 serves to unite the os calcis and astragalus solidly together. The 



* A posterior view of the ankle joint. 1. The lower part of the interosseous mem- 

 brane. 2. The posterior inferior ligament connecting the tibia and fibula. 3. The 

 transverse ligament. 4. The internal lateral ligament. 5. The posterior fasciculus 

 of the external lateral ligament. 6. The middle fasciculus of the external ligament. 

 7. The synovial membrane of the ankle joint. 8. The os calcis. 



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