THE ARTICULATIONS OF THE FOOT. 



193 



menfc run from the inner extremity of the sustentaculum, in a radiating manner 

 forwards and upwards, to be fixed to the back of the tuberosity and the inner part 

 of the upper surface of the navicular bone, being joined by the anterior fibres of the 

 deltoid ligament of the ankle-joint, which descend from the internal malleolus. The 

 deep surface of the ligament is smooth and forms a part of the articular socket for 

 the head of the astragalus. On the superficial aspect of the upper portion of the 

 ligament is another smooth surface where the tendon of the tibialis posticus is in 

 contact with it. The ligament occasionally contains an ossification. The external 

 or superior calcaneo-navicular ligament (fig. 222, 8 ; 223) forms the external boundary 

 of the socket just mentioned, and lies deeply at the anterior part of the fossa (sinus 

 tarsi) between the astragalus and os calcis. Its fibres, very short, are directed 



Fig. 221. LIGAMENTS OF THE FOOT, FROM THE INNER SIDE. (Allen Thomson.) \ 



1, internal lateral ligament of the ankle ; x , below the sustentaculum tali, showing part of the 

 internal lateral ligament descending upon it ; 2, internal, and 3, posterior astragalo-calcaneal ligaments ; 

 4, part of the long and short plantar ligaments seen from the inside ; 5, astragalo -navicular ligament ; 

 6, superior part of the internal calcaneo-navicular ligament, with the cartilaginous surface for the 

 tibialis posticus tendon ; 7, 8, first, 9, second dorsal naviculo-cuneiform ligaments ; 10, intercuneiform, 

 or trasverse dorsal cuneiform, between the first and second cuneiform bones ; 11, first dorsal tarso- 

 metatarsal ligament ; 12, first plantar tarso-metatarsal ; 13, internal lateral metatarso-phalangeal ; the 

 internal sesamoid bone is seen below ; 14, internal lateral interphalangeal ligament of the first toe. 



from behind forwards and inwards between the contiguous extremities of the bones. 

 They are attached posteriorly to the foremost part of the upper surface of the os 

 calcis between the articular surfaces for the astragalus and cuboid, and anteriorly to 

 the outer side of the navicular bone. 



The astragalo-navicular ligament, a membranous band situated on the 

 dorsum of the foot, consists of two portions which converge as they pass forwards 

 from the head of the astragalus to the upper surface of the navicular bone, and com- 

 pletes the fibrous capsule of the astragalo-calcaneo-navicular joint, formed in the 

 rest of its extent by the internal and external calcaneo-navicular ligaments. 



The two synovial cavities of these articulations are separated by the interosseous 

 ligament (fig. 223): the posterior belongs to the astragalo-calcaneal joint, the ante- 

 rior to the astragalo-calcaneo-navicular articulation. 



CALCANEO-CUBOID ARTICULATION. The calcaneum is united to the cuboid bone 

 by a synovial joint with surrounding ligaments. 



