THE KNEE-JOINT 



333 



Femur. 



The external lateral or long external lateral ligament (ligamentum collaterale 



fibulare) (Figs. 267 and 271) is a strong-, rounded, fibrous cord situated nearer 



to the back than the front of the joint. It is attached, above, to the back part 



of the outer tuberosity of the femur; below, 



to the outer part of the head of the fibula. 



Its outer surface is covered by the tendon 



of the Biceps femoris, which divides at its 



insertion into two parts, separated by the 



ligament. The' ligament has, passing be- 

 neath it, the tendon of the Popliteus muscle 



and the inferior external articular vessels 



and nerve. 

 The short external lateral ligament 



(ligamentum laterale externum breve sen 



posticum) (Fig. 267) is not a constant 



structure. It is an accessory bundle of 



fibres placed behind and parallel with the 



preceding, attached, above, to the lower 



and back part of the outer tuberosity of the 



femur; below, to the summit of the styloid 



process of the fibula. This ligament is in- 

 timately connected with the capsular liga- 

 ment, and has, passing beneath it, the 



tendon of the Popliteus muscle and the 



inferior external articular vessels and nerve. 

 The crucial ligaments (ligamenta cru- 



ciata genu) (Figs. 268 and 269) are two 



interosseous ligaments of considerable 



strength situated in the interior of the joint, 



nearer its posterior than its anterior part. 



They are called crucial because they cross 



each other somewhat like the lines of the 



letter X; and have received the names anterior crucial and posterior crucial, from 



the position of their attachment to the tibia. 

 The anterior or external crucial ligament (ligamentum cruciatum anterius) (Fig. 



268) is attached to the depression in front of the spine of the tibia, being blended 



with the anterior extremity 

 of the external semilunar 

 fibrocartilage, and, passing 

 obliquely upward, backward, 

 and outward, is inserted into 

 the inner and back part of 

 the outer condyle of the 

 femur. 



The posterior or internal 

 crucial ligament (ligamen- 

 tum cruciatum posterius) is 

 stronger, but shorter and 

 less oblique in its direction 

 than the anterior. It is at- 

 tached to the back part of 

 the depression behind the 



spine of the tibia, to the popliteal notch, and to the posterior extremity of the 



external semilunar fibrocartilage; and passes upward, forward, and inward, to 



FIG. 268. Right knee-joint, 

 ligaments. 



Showing internal 



FIG. 269. Head of tibia, with semilunar cartilages, etc. 

 above. Right side. 



Seen from 



