134 TIBIO-FIBULAR ARTICULATION. 



put upon the stretch, serves to press the adipose mass into the vacuity 

 formed in the front of the joint. In extension all the ligaments are 

 put upon the stretch with the exception of the ligamentum patella?. 

 When the knee is semi-flexed, a partial degree of rotation is 

 permitted. 



3. Articulation between the Tibia and Fibula. The tibia and 

 fibula are held firmly connected by means of seven ligaments, viz. 



Anterior, ) , 



> above. 

 Posterior, } 



Interosseous membrane, 

 Interosseous inferior, 



Anterior, j ^ 

 Posterior, ) 

 Transverse. 



The anterior superior ligament is a strong fasciculus of parallel 

 fibres passing obliquely downwards and outwards from the inner 

 tuberosity of the tibia, to the anterior surface of the head of the 

 fibula. 



The posterior superior ligament is disposed in a similar manner 

 upon the posterior surface of the articulation. 



There is a distinct synovial membrane in this articulation. 



The interosseous membrane or superior interosseous ligament is a 

 broad layer of aponeurotic fibres passing obliquely downwards and 

 outwards, from the sharp ridge on the tibia, to the inner edge of the 

 fibula and crossed at an acute angle by a few fibres passing in the 

 opposite direction. The ligament is deficient above, leaving a con- 

 siderable interval between the bones, through which the anterior 

 tibial artery takes its course forwards to the anterior aspect of the 

 leg, and near its lower third there is an opening for the anterior 

 peroneal artery and vein. 



The interosseous membrane is in relation, in front, with the 

 tibialis anticus, extensor longus digitorum, and extensor proprius 

 pollicis muscle, with the anterior tibial vessels and nerve, and with 

 the anterior peroneal artery ; and behind with the tibialis posticus, 

 and flexor longus digitorum muscle, and with the posterior peroneal 

 artery. 



The inferior interosseous ligament consists of short and strong 

 fibres, which hold the bones firmly together, inferiorly, where they 

 are nearly in contact. This articulation is so firm that the fibula 

 is likely to be broken in the attempt to rupture the ligament. 



The anterior inferior ligament is a broad band, consisting of two 

 fasciculi of parallel fibres that pass obliquely across the anterior as- 

 pect of the articulation of the two bones at their inferior extremity, 

 from the tibia to the fibula. 



The posterior inferior ligament (fig. 64. 2) is a similar band upon 

 the posterior surface of the articulation. Both ligaments project 



