THE FOOT. 



565 



front by short fibrous bands which help to form the capsule. The under surface of the sub- 

 astragaloid joint is formed first by the surface of the scaphoid, next by the inferior calca- 

 neoscaphoid ligament, then by the upper surface of the sustentaculum tali, then by the 

 interosseous ligament, and finally by the posterior surface of the os calcis. The infe- 

 rior calcaneoscaphoid ligament is the most important one in maintaining the integrity of 



Groove for flexor longus 

 hallucis 



Sustentaculum tali 



Internal lateral ligament 

 Anterior tibial tendon 



Posterior tibial tendon 

 Groove for posterior 

 tibial tendon on the 

 inferior calcaneo- 

 scaphoid ligament 

 Groove for flexor longus digitorum 



FIG. 583. View of inner side of ankle-joint, showing the internal lateral ligament. 



the arch (Fig. 582). In addition, in order to provide against luxation, which is favored 

 by the superincumbent body weight, the joint is strengthened by three ligaments, viz. : 



1. The interosseous astragalo-calcaneal ligament, which runs obliquely forward 

 and outward between the os calcis and astragalus and divides the subastragaloid joint 

 into an anterior and posterior portion. It is very strong (Fig. 582). 



2. The internal lateral {deltoid} ligament of the ankle, which sends fibres by 



Anterior fasciculus of external 

 lateral ligament 



Astragalocalcaneal ligament 



Anterior tibiofibular 

 ligament 



Posterior (transverse) tibio- 

 fibular ligament 



Posterior fasciculus of 

 sxternal lateral ligament 

 Middle fasciculus of 

 external lateral ligament 



Interosseous ligament 

 FIG. 584. Ligaments of the outer side of the ankle. 



its deep part from the tibia above to the side of the astragalus below and likewise to 

 the scaphoid in front, and by its superficial part to the sustentaculum tali (Fig. 583). 

 3. The external lateral ligament of the ankle, the anterior and posterior fascic- 

 uli of which are both attached to the astragalus and the middle fasciculus of which 

 goes to the os calcis below (Fig. 584). 



