192 



THE ARTICULATIONS OF THE LOWER LIMB. 



when the ligaments are least stretched, a limited degree of lateral motion is allowed under 

 the influence of external force, but it is probable that such movements do not occur naturally. 

 In the eiect attitude the line of gravity of the body falls slightly in front of the ankle-joint, 

 and a certain amount of muscular effort is required to maintain the position of the leg-bones ; 

 but stability is to some extent secured by the obliquity of the axis of the ankle-joint, which 

 forms with its fellow, owing to the outward direction of the foot, an angle, open backwards, 

 of about 130. 



THE ARTICULATIONS OF THE FOOT. 



ARTICULATIONS OF THE ASTRAGALUS WITH THE CALCANEUM AND NAVICULAR 

 BONE. The astragalus is connected with the calcaneum by two synovial articula- 

 tions, viz., by a posterior one peculiar to those two bones, and by an anterior one 

 common to them with the navicular bone. Two strong ligaments also unite the 

 navicular bone to the calcaneum. 



Astragalo-calcaneal ligaments. The interosseous ligament (fig. 223), broad 

 and strong, passes downwards from the groove between the anterior and posterior 



Fig. 220. LIGAMENTS OF THE FOOT, SEEN FROM BELOW. 

 (Allen Thomson. ) \ 



1 and 2, portions of the internal lateral ligament of the ankle- 

 joint ; 3, long, and 3', short plantar ligaments ; 4, internal cal- 

 caneo-navicular ligament ; 5, three naviculo-cuneiform ligaments ; 

 6, is placed upon the external cuneiform bone, towards which is 

 seen coming from behind a cubo-cuneiform ligament ; 7, is placed 

 upon the internal cuneiform bone ; from 6 and 7, are seen passing 

 forwards the plantar cuneo-metatarsal ligaments ; x , part of the 

 first dorsal cuneo-metatarsal ligament ; 8, plantar band from cuboid 

 to fifth metatarsal bone ; 9. fibres prolonged from the long plantar 

 ligament, forming the sheath of the peroneus longus tendon ; 10, 



10, between these figures the plantar intermetatarsal ligaments ; 



11, 11, transverse metatarsal ligament ; 12, intersesamoid liga- 

 ment ; 13, 13, between these figures are seen the five pairs 

 of internal and external lateral metatarso-phalangeal ligaments ; 

 14, 14, between these figures are seen the five pairs of in- 

 ternal and external lateral interphalangeal ligaments of the first 

 series ; those of the second series have no figure placed to mark 

 them ; 15, plantar ligament of the interphalangeal articulation of 

 the great toe. 



articular surfaces of the astragalus to the similar 

 groove between the corresponding articular surfaces 

 of the calcaneum. The posterior ligament (fig. 22 1 , 3), 

 thin and membranous, consists of short fibres which 

 radiate from the external tubercle of the astragalus to 

 the adjacent upper and inner part of the calcaneum. A 



small internal ligament (fig. 221, 2) runs forwards from the internal tubercle of the 

 astragalus to the back of the sustentaculum tali, its upper fibres being continued 

 into the internal calcaneo-navicular ligament. There is also an inconstant external 

 litjament (fig. 218, 6), a slight fasciculus of fibres, which descends from the outer 

 surface of the astragalus to the outer side of the calcaneum, parallel with the middle 

 division of the external lateral ligament of the ankle-joint. It may be farther ob- 

 served, that those portions of the lateral ligaments of the ankle-joint which pass 

 down over the astragalus to the os calcis assist in uniting these two bones. 



Calcaneo-navicular ligaments. The internal or inferior lif/ament is a broad 

 and thick band, in great part fibro-cartilaginous, which occupies the interval 

 between the sustentaculum tali and the navicular bone on the plantar aspect and 

 inner border of the foot. Its lower part springs from the anterior margin of the 

 sustentaculum tali, and is directed forwards and inwards to the inferior surface of 

 the navicular bone. Continuous with this, the fibres of the upper part of the liga- 



