222 



DISSECTION OF THE LEG. 



Interosse- 

 ous mem- 

 brane be- 

 tween the 

 shafts : 



attach- 

 ments ; 



apertures. 



Motion 

 slight, 



in upper, 

 and lower 

 articula- 

 tion. 



The INTEROSSEOUS MEMBRANE fills the interval between the 



bones of the leg, and serves as an aponeurotic partition between! 



the muscles on the front and back of the limb. Its fibres are! 



directed for the most part downwards from the tibia to the fibula ;| 



but a few cross in the opposite direction. 



Internally it is fixed to the outer edge of the tibia ; and externally, 



to the prominent interosseous ridge on the inner side of the fibula. 



In its upper part, close to the neck of the fibula, is an oval opening 



about an inch in length, which transmits the anterior tibial vessels ; 



and at the lower end, between the membrane and the inferior < 



articulation, is another 

 small opening for the an- 

 terior peroneal vessels. 



Movement. Very little 

 movement is allowed in 

 the tibio-libular articula- 

 tions, as the chief use of 

 the fibula is to give 

 strength and elasticity to 

 the ankle-joint, and attach- 

 ment to muscles of the 

 leg. 



In the upper joint there 

 is a slight gliding chiefly 

 from within out. In the 

 lower articulation the liga- 

 ments permit some yield- 

 ing of the fibula to the 

 pressure of the astragalus, 

 as when the weight of the 

 boc ^ ^ thrown on the 

 inner side ot the loot ; 

 but if the force is violent 

 the fibula will be fractured 



about the junction of the third and lowest fourths sooner than the 



ligaments give way. 



FIG. 85. INNER SIDE OP THE ANKLE 

 (ALTERED FROM BOURGERY). 



1. Posterior, 2, middle, and 3, anterior 

 fibres of the inner lateral ligament. 



4. Internal calcaneo-navicular ligament. 



Bones in 

 the ankle- 

 joint. 



Dissection 

 of the ankle- 

 joint. 



ARTICULATION OF THE ANKLE (figs. 85 and 86). 



The ankle is a hinge joint, in which the upper part of the 

 astragalus is received into an arch formed by the lower ends of the 

 tibia and fibula ; and the four ligaments belonging to this kind of 

 articulation connect together the bones. 



Dissection. To make the dissection required for the ligaments 

 of the ankle-joint, the muscles and the fibrous tissues and vessels 

 must be removed from the front and back of the articulation. 



For the purpose of defining the lateral ligaments, the limb must 

 be placed first on one side and then on the other. The internal 

 ligament is wide and strong, and lies beneath the tendon of the 

 tibialis posticus. The external is divided into three separate pieces ; 



