156 TARSOMETATARSAL ARTICULATIONS. 



its fibres being continued onwards to the bases of the third and fourth 

 raetatarsal 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 situ- 

 ated 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 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 cakaneo-astraya- 

 loid, 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 astra- 

 galus solidly together. The second interosseous ligament, also very 

 strong, is situated between the sides of the scaphoid and cuboid bone ; 

 while the three remaining interosseous ligaments connect strongly 

 together the three cuneiform 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 calcaneo-astragaloid and astragalo-scaphoid articulation. Occa- 

 sionally an additional small synovial membrane is found in the an- 

 terior calcaneo-astragaloid joint ; a third, for the calcaneo-cuboid arti- 

 culation ; 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 between the internal and 

 middle cuneiform bones. A small synovial membrane is sometimes 

 met with between the contiguous surfaces of the scaphoid and cuboid 

 bone. 



Actions. The movements permitted by the articulation between 

 the astragalus and os calcis, are a slight degree of gliding, in the direc- 

 tions forwards and backwards and laterally from side to side. The 

 movements of the second range of tarsal bones is very trifling, being 

 greater between the scaphoid and three cuneiform bones than in the 

 other articulations. The movements occurring between the first and 

 second range are the most considerable ; they are adduction and abduc- 

 tion, and, in a minor degree, flexion, which increases the arch of the 

 foot, and extension which flattens the arch. 



6. Tarso-metatarsal Articulation. The ligaments of this articula- 

 tion are, 



Dorsal, 



Plantar, 



Interosseous. 



