ARTICULATION OF ASTKAU ALL'S AND OS CALCIS. 



The posterior ligament (fig. 87, a) consists of a few fibres between posterior, 

 he 1 'ones, where they are grooved by the tendon of the flexor 

 liallucis ; the internal liijamtnt is a small band passing from the internal, 

 ^[internal tubercle of the astragalus to the sustentaculum tali ; and 



he i.'.'.-ti.rital ligament (6) is connected to the sides of the astragalus external, 

 and os calcis, near the middle piece of the external lateral ligament 

 the ankle-joint. 



The inttrosseov.s ligament (fig. 87, c) consists of strong vertical and int-eros- 

 ind oblique fibres, which are attached above and below to the mentis! 18 * 

 depressions on the opposed surfaces of the two bones. This 

 .nd extends across between the bones, and its depth is greatest 

 |at the outer side. 



In a subsequent stage of the dissection (p. 228) the articular Articular 



If* 



Fn;. 87. VIEW OF THE DORSAL LIGAMENTS OF THE TARSUS. 



a. Posterior. I. external, and c, 

 iateroBaeoaa ligaments between astra- 

 galus and os calcis. 



d. Astragalo-navicular. 



f. External calcaneo-navicular. 



/. Internal, and g, upper caleaneo- 

 cuboid ligaments. 



h. Dorsal naviculo-cuboid band. 



/. k, I, Dorsal external, middle, 

 and internal naviculo-cuneiform longi- 

 tudinal bands. 



//. Dorsal transverse bands between 

 the cuneiform and cuboid bones. 



surfaces of the bones will be seen, viz., one behind the interosseous 

 ligament, and one in front of it, with two synovial cavities. 



oi-i-im-Ht*. It is between the astragalus and os calcis that the 



, 



important movements of the foot known as inversion and eversion 



chiefiy take place. The motion is one of rotation about an oblique 

 axis, which is directed from the upper and inner part of the head 

 of the astragalus, backwards, downwards, and outwards to the lower 

 and outer part of the posterior extremity of the os calcis. Supposing 

 the astragalus fixed between the malleoli, and the rest of the foot 

 free to move, then in 'inc'-r*ion the outer part of the os calcis moves 

 I'm' wards an^down wards, and the sustentaculuin tali in the opposite 

 direction, whrte-4^ie anterior end of the bone is carried somewhat 

 inwards. As a result of this, aided by corresponding movements 

 of the anterior tar sal bones, the fore part of the foot is depressed, 

 D.A. Q 



synpvial 



^ 

 Movement 



between as- 



axis of 

 motion. 



Inversion. 



