298 THE ARTICULATIONS OR JOINTS. 
fibula, whereas in dorsiflexion, as in raising the fore part of the foot from the ground, the widest 
nart of the astragalus is forced back between the tibia and fibula; but notwithstanding the dif- 
Pecnte between these two movements, the fibula remains in close contact with the astragalus by 
reason of the action of the transverse inferior fibro-fibular ligament and the posterior talo-fibular 
ligament, so that lateral movement is prevented, 
It is doubtful whether lateral movement at the ankle-joint can be obtained by any natural 
movement of the foot, although it is generally believed that in the position of partial extension 
a small amount of lateral movement may be produced by the application of external force. 
“This apparent play” of the ankle-joint during extension “is really due to oscillation of the 
small bones of the foot on each other, largely of the scaphoid on the astragalus, but also of the 
cuboid on the caleaneum. Excessive mobility of these latter is restrained by an important 
function of the posterior tubercle of the cuboid which locks into a notch in the os caleis” 
(Blake). 
INTERTARSAL JOINTS. 
These joints (articulationes intertarsez) are all diarthroses in which the gliding 
movement is characteristic, as in the carpus. With the view of obtaining a proper con- 
ception of the many beautiful mechanical principles involved in the construction of the 
foot, it is necessary to study these articulations with considerable attention to detail. 
Articulatio Talo-calcanea.—The astragalus and os calcis articulate with each 
other in the articulatio talo-calcanea. 
This joint is situated between the inferior facet on the body of the astragalus 
and a corresponding facet on the upper aspect. of the hinder part of the os calcis. 
On each bone the articulation is limited in front by a wide deep groove which 
runs obliquely across each bone from within outwards and forwards. 
The supporting and investing ligaments form a capsule, consisting for the most 
part of short fibres, but the joint derives additional strength from the external and 
Anterior ligament of ankle Ant. inf. tibio-fibular ligament 
Caleaneo-seaphoid ligament ! | Post. inf. tibio-fibular ligament 
Dorsal scapho-cuboid ligaments 
Dorsal scapho-cuneiform ligaments 
Dorsal intercuneiform ligaments 
\ 
Dorsal cubo-cuneiform ligament: \ 
Ant. fasciculus 
of ext. lat. ligament 
Middle fasciculus 
—<—-\ of ext. lat. ligament 
Dorsal tarso-metatarsal ligaments NK 
‘ \\ 
NS 
Dorsal inter- 
metatarsal ligaments “Ss 
o£ 
Internal caleaneo-cuboid Jigament 
\ / ae 
a : a \. “Ant. calcaneo-astragaloid ligament 
Dorsal calcaneo-cuboid ligament X 
\_ Interosseous caleaneo- 
Inferior calcaneo-cuboid ligament astragaloid ligament 
External calcaneo-cuboid ligament NN Ext. calcaneo-astragaloid ligament 
Fic, 229.—LIGAMENTS ON OUTER ASPECT OF ANKLE AND ON DoRSUM AND OuUTER ASPECTS OF Foot. 
internal lateral ligaments of the ankle-joint. The capsule is subdivided into the 
following astragalo-calcaneal or talo-caleaneal bands :— 
The anterior talo-calcaneal ligament (Fig. 229) consists of a band of short 
fibres placed immediately in relation to the anterior end of the deep groove which 
bounds the articular facets. They are attached to the antero-external aspect of 
the neck of the astragalus, from which they extend downwards to the adjacent 
superior surface of the os calcis. 
The external talo-calcaneal ligament (Fig. 229) is in continuity with the hinder 
border of the preceding ligament, and it is placed parallel to, but on a deeper 
plane than, the middle fasciculus of the external lateral ligament of the ankle- 
joint. It consists of short fibres passing between the adjacent rough outer margins 
of the two bones. 
The posterior talo-calcaneal ligament (Fig. 229) closes the joint cavity on its 
posterior aspect. It consists of fibres which radiate from the posterior aspect of 
y 
