282 THE ARTICULATIONS. 



end of the tibia, not more than half an inch. If any diseased tissue still appears to be left in 

 the bones, it should be removed with the gouge rather than that a further section ot the bones 

 should be made. 



III. Articulations between the Tibia and Fibula. 



The articulations between the tibia and fibula are effected by ligaments which 

 connect both extremities, as well as the shafts of the bones. They may, con- 

 sequently, be subdivided into three sets : 1. The Superior Tibio-fibular articula- 

 tion. 2. The Middle Tibio-fibular ligament or interosseous membrane. 3. The 

 Inferior Tibio-fibular articulation. 



1. SUPERIOR TIBIO-FIBULAR ARTICULATION. 



This articulation is an arthrodial joint. The contiguous surfaces of the bones 

 present two flat, oval facets covered with cartilage, and connected together by the 

 following ligaments : 



Capsular. 



Anterior Superior Tibio-fibular. 



Posterior Superior Tibio-fibular. 



The Capsular Ligament consists of a membranous bag which surrounds the 

 articulation, being attached around the margins of the articular facets on the tibia 

 and fibula, and is much thicker in front than behind. 



The Anterior Superior Ligament (Fig. 185) consists of two or three broad and 

 flat bands which pass obliquely upward and inward from the front of the head of 

 the fibula to the front of the outer tuberosity of the tibia. 



The Posterior Superior Ligament (Fig. 184) is a single thick and broad band 

 which passes upward and inward from the back part of the head of the fibula to 

 the back part of the outer tuberosity of the tibia. It is covered by the tendon of 

 the Popliteus muscle. 



A Synovial Membrane lines this articulation, which at its upper and back part 

 is occasionally continuous with that of the knee-joint. 



2. MIDDLE TIBIO-FIBULAR LIGAMENT OR INTEROSSEOUS MEMBRANE. 



An interosseous membrane extends between the contiguous margins of the 

 tibia and fibula, and separates the muscles on the front from those on the back of 

 the leg. It consists of a thin, aponeurotic lamina composed of oblique fibres 

 which for the most part pass downward and outward between the interosseous ridges 

 on the two bones ; some few fibres, however, pass in the opposite direction, down- 

 ward and inward. It is broader above than below. Its upper margin does not 

 quite reach the superior tibio-fibular joint, but presents a free concave border, above 

 which is a large, oval aperture for the passage of the anterior tibial vessels forward 

 to the anterior aspect of the leg. At its lower part is an opening for the passage 

 of the anterior peroneal vessels. It is continuous below with the inferior inter- 

 osseous ligament, and is perforated in numerous parts for the passage of small vessels. 

 It is in relation, in front, with the Tibialis anticus, Extensor longus digitorum, 

 Extensor proprius hallucis, Peroneus tertius, and the anterior tibial vessels and 

 nerve ; behind, with the Tibialis posticus and Flexor longus hallucis. 



3. INFERIOR TIBIO-FIBULAR ARTICULATION. 



This articulation is formed by the rough, convex surface of the inner side of 

 the lower end of the fibula, connected with a concave rough surface on the outer 

 side of the tibia. Below, to the extent of about two lines, these surfaces are 

 smooth, and covered with cartilage,, which is continuous with that of the ankle- 

 joint. The ligaments of this joint are 



Anterior Inferior Tibio-fibular. Transverse or Inferior. 



Posterior Inferior Tibio-fibular. Inferior Interosseous. 



