166 TARSAL ARTICULATIONS. 



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

 band of ligament, which passes forwards from the anterior and inner bor- 

 der of the os calcis and scaphoid bone. In addition tu 

 connecting the os calcis and scaphoid, it supports the 

 astragalus, and forms part of the cavity in which the 

 rounded head of the latter bone 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 articu- 

 lation, are conditions favourable to the occasional disloca- 

 tion of the head of the astragalus. 



The long calcaneo-cuboid ligamentum, or longum plantce, 

 is a long band of ligamentous fibres, which proceeds from 

 the under surface of the os calcis to the rough surface on 

 the under part of the cuboid bone, its fibres being con- 

 tinued 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 in- 

 sertion in 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 sepa- 

 rated by adipose tissue ; it is broad and extensive, and ties the under 

 surfaces 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 second interosseous ligament, also very strong, is situated 

 between the sides of the scaphoid and cuboid bone ; while the three re- 

 maining interosseous ligaments connect strongly together the three cunei- 

 form bones and the cuboid. 



The synovial membranes of the tarsus are four in number ; one for the 

 posterior calcaneo-astragaloid articulation ; a second, for the anterior cal- 

 caneo-astragaloid and astragalo-scaphoid articulation. Occasionally an 

 additional small synovial membrane is found in the anterior calcaneo- 

 astragaloid joint ; a third^ for the calcaneo-cuboid articulation ; and a 

 fourth, the large tarsal synovial membrane, for the articulations between 

 the scaphoid and three cuneiform bones, the cuneiform bones with each 

 other, the external cuneiform bone with the cuboid, and the two external 

 cuneiform bones with the bases of the second and third metatarsal bones. 

 The prolongation which reaches the metatarsal bones passes forwards be- 

 tween the internal and middle cuneiform bones. A small synovial mem- 

 brane is sometimes met with between the contiguous surfaces of the 

 scaphoid and cuboid bone. 



* 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. Tlio 

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

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

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



