230 ARTICULATIONS. 



1. ARTICULATION OF THE FIRST Eow OF TARSAL BONES. 



The articulation between the astragalus and os calcis is an arthrodial joint 

 connected together by three ligaments : 



External Calcaneo-astragaloid. Posterior Calcaneo-astragaloid. 



Interosseous. 



The External Calcaneo-astragaloid Ligament (fig. 144) is a short, strong fasci- 

 culus, passing from the outer surface of the astragalus, immediately beneath its 

 external malleolar facet, to the outer edge of the os calcis. It is placed in front 

 of the middle fasciculus of the external lateral ligament of the ankle-joint, with 

 the fibres of which it is parallel. 



The Posterior Calcaneo-astragaloid Ligament (fig. 143) connects the posterior 

 extremity of the astragalus with the upper contiguous surface of the os calcis ; it 

 is a short narrow band, the fibres of which are directed obliquely backwards and 

 inwards. 



The Interosseous Ligament forms the chief bond of union between these bones. 

 It consists of numerous vertical and oblique fibres, attached, by one extremity, 

 to the groove between the articulating surfaces of the astragalus; by the other, 

 to a corresponding depression on the upper surface of the os calcis. It is very 

 thick and strong, being at least an inch in breadth from side to side, and serves 

 to unite the os calcis and astragalus solidly together. 



The Synovial Membranes (fig. 146) are two in number ; one for the posterior 

 calcaneo-astragaloid articulation ; a second for the anterior calcaneo-astragaloid 

 joint. The latter synovial membrane is continued forwards between the contigu- 

 ous surfaces of the astragalus and scaphoid bones. 



2. ARTICULATIONS OF THE SECOND Eow OF TARSAL BONES. 



The articulations between the scaphoid, cuboid, and three cuneiform are effected 

 by the following ligaments : 



Dorsal. Plantar. 



Interosseous. 



The Dorsal Ligaments are small bands of parallel fibres, which pass from each 

 bone to the neighboring bones with which it articulates. 



The Plantar Ligaments have the same arrangement on the plantar surface. 



The Interosseous Ligaments are four in number. They consist of strong trans- 

 verse fibres, which pass between the rough non-articular surfaces of adjoining 

 bones. There is one between the sides of 'the scaphoid and cuboid; a second 

 between the internal and middle cuneiform bones ; a third between the middle and 

 external cuneiform ; and a fourth between the external cuneiform and cuboid. 

 The scaphoid and cuboid, when in contact, present each a small articulating facet, 

 covered with cartilage, and lined either by a separate synovial membrane, or by 

 an offset from the common tarsal synovial membrane. 



3. ARTICULATIONS OF THE Two Eows OF THE TARSUS WITH EACH OTHER. 



These articulations may be conveniently divided into three sets. ]. The arti- 

 culation of the os calcis' with the cuboid. 2. The os calcis with the scaphoid. 

 3. The astragalus with the scaphoid. 



1. The ligaments connecting the os calcis with the cuboid are four in number : 



y. 1 j Superior Calcaneo-cuboid. 



j Internal Calcaneo-cuboid or Interosseous. 



Long Calcaneo-cuboid. 

 Plantar, j Sho Calcaneo . cuboicL 



