170 / 7/ /. AltTICULA T10NS. 



a fibre-cartilaginous thickening, 00 which glides the performs tnidii. It 

 is attached, above, to the tibia, bi-lw, to (he; Mtngftlufl and nilc-is; at its 

 it is mixed with tho two superficial lateral ligaments, and the astragal i:in 

 fasciculus of tho middle internal ligament. Its internal face is lined by 

 articular synovial membrane ; tho external is covered and lubricated by tho 

 vaginal serous membrane which facilitates the gliding of tho perfonms 

 tendon in the tarsal sheath. 



Synovial membrane. This membrane is developed at tho internal face 

 of tho two capsular ligaments, nearly covers the three internal ligaments, 

 and linos tho external deep ligament. It communicates, in front an! below, 

 with tho synovial membrane proper to the articulation of the two rows of 

 tarsal bones. When it becomes the seat of dropsical effusion, it is al 

 distended forwards and inwards, because it is only sustained at that plan 

 by the anterior capsular ligament. But tho effusion may also raise tin- 

 posterior ligament and produce hernia in the hollow of the hock, behind tho 

 lateral ligaments. It is not, therefore, absolutely correct to attribute all the 

 synovial tumours in the hollow of tho hock to dilatation of the tarsal 

 tendinous sheath. 



Movements. Nothing can bo less complicated than the mechanism of the 

 tibio-tarsal articulation ; this joint only permitting two opposite movements, 

 those of flexion and extension, which are so simple and precise that we may 

 dispense with a description of the manner in which they are executed. It 

 may only be remarked that, in order to prevent contact between tho leg 

 and foot during flexion, tho latter fraction of the limb deviates a little 

 outwards, owing to the marked obliquity of the articular grooves. 



ARTICULATION OF THE BONES OF THE FIRST Row, OR CALOANEO- 

 ASTRAOALOID ARTICULATION. This is a compound arthrodial joint, resulting 

 from the coaptation of the three or four articular facets of the posterior face 

 of the astragalus with the analogous facets of the calcis. 



This joint is maintained by the lateral ligaments of tho tibio-tarsal 

 articulation, and by four calcaneo-astragaloid ligaments a superior, external, 

 internal, and the last interosseous. 



The superior calcaneo-astragaloid ligament is formed of short parallel 

 fibres thrown across from one bone to the other, and is situated towards the 

 superior extremity of the pulley of the astragalus ; it is lined superiorly by 

 the synovial membrane of the tibio-tarsal articulation. 



The lateral ligaments are two very thin fasciculi concealed by the 

 ligaments which bind, laterally, the tibia to the tarsal bone. 



The interosseous ligament is very strong, and occupies a great portion of 

 tfee rugged excavation which separates the articular facets. 



This articulation does not usually possess proper synovial capsules. 

 Two prolongations of tho synovial membrane of the two rows, in ascending 

 between tho calcis and astragalus, facilitate the gliding of tho two inferior 

 facets. An analogous prolongation of tho tibio-tarsal synovial membrane is 

 effected for the superior facets, and it is not rare to find this prolongation 

 form a distinct capsule. 



Movements nearly null. 



ARTICULATION OF THE BONES OF THE SECOND Row WITH EACH OTHER. 

 These bones, four in number, are brought into contact in tho following 

 manner : The cuboides responds to tho scaphoid by two facets, one anterior, 

 tho other posterior ; it articulates with tho great cuneiform by two similar 

 facets, tho posterior of which is not always present. Tho scaphoid is unitl 

 to the two cuneiforms by the largo convex facet occupying its entire lower 



