The Lower Extremity and Pelvis 149 



transference to the tibia. On the other hand, looking at them from below, the inner 

 is seen to be longer and curved ; this is probably in association with the terminal rotation 

 that occurs round the attachment of the anterior crucial ligament when the leg is fully 

 extended, when the inner part of the tibia moves forward on the femur or the femur 

 backward on the tibia, if the foot is on the ground while the outer condyle is held in 

 position by the attachment of the anterior crucial ligament to it. The attachments of 

 the two crucial ligaments are shown in Fig. 122, and the centre of the curve made by the 

 inner condyle is on the attachment of the anterior ligament to the outer condyle. 



The two condyles are on the same horizontal level when the bone is in its natural 

 position, so that a femur placed with its condyles on the table is in the inclined direction 

 that it occupied in the body. It makes in this way an angle of about 9 degrees with 

 the vertical, a little greater in woman, and at the same time sloping downward and 

 forward at an angle of about 4 degrees or 5 degrees with the transverse vertical plane. 



The popliteal surface is limited below by the intercondylic ridge to which the 

 posterior ligament is attached. It is covered in for the most part by the belly of Semi- 

 membranosus and externally by Biceps. Observe that the inner head of the Gastro- 

 cnemius encroaches on this space, there being a tuberculated roughness for it on the 

 bone, so that the inner superior articular artery crosses over this head, whereas the outer 

 vessels lie above the level of the origin of the outer head (Fig. 120). 



When the inner vessels have crossed the inner head they come to the tendon of Adductor 

 magnus on the supracondylar line : piercing this close to the bone they find themselves under 

 cover of Vastus internus, which we have seen arises from this tendon and not from the bone. The 

 outer vessels lie on bone all the way, passing deep to Biceps, Ilio-tibial band, and Vastus externus. 



The two heads (Fig. 120) of Gastrocnemius arise largely from the vertical capsular 

 fibres that cover the back of the condylar recesses of the joint, but they each reach 

 the bone above : the outer tendon is attached to the well-marked facet seen in Fig. 122, 

 and the inner tendon, in addition to the popliteal origin already mentioned, has a facet 

 of attachment in a corresponding situation behind and below the Adductor tubercle 

 (Fig. 122). There is usually a small sesamoid bone or cartilage to be found in the 

 tendinous origin of the outer head, and rarely one in the inner head in old people. 

 The " facets " may be looked on as representing the positions of small bursal prolonga- 

 tions from the joint deep to these sesamoids. 



Below the Gastrocnemius facet on the outer condyle is a tubercle for the external 

 lateral ligament, and below this again is a groove from the front end of which the 

 Popliteus arises. The inner condyle is prominent below the Adductor tubercle : the 

 internal lateral ligament is attached below the most prominent spot. 



The side of each condyle is covered below and in front by synovial membrane, 

 which is reflected on to the capsule along an oblique line directed downwards and back- 

 wards. The line passes to the under side of the attachment of each lateral ligament : 

 behind this it turns up to become continuous with the attachment of the condylar 

 portion of the capsule. Each condylar capsule extends up to the bone a little above the 

 articular surface, and is lost in the intercondylar fossa by becoming continuous with the 

 areolar tissue behind the crucial ligament and with the ligaments themselves. The 

 synovial sac of the condylar recesses does not extend further toward the intercondylar 

 fossa than the margin of the articular surface, but the main cavity extends back for 

 some distance from the trochlear surface on to the crucial ligaments and comes into 

 relation with the floor of the fossa between these ligaments (Fig. 122). The cartilage- 

 covered surfaces rest below on the interarticular (semilunar) fibre-cartilages, and the 



