Fig. 178. Sagittal Section through the Left Knee-joint during 



Flexion. 



This preparation was made from a man aged 82 years. Formal was injected 

 into t/ie limb, and the knee, forthwith, flexed to its utmost limit, was kept in 

 that position. On the following day the section was made without freezing. 

 In spite of advanced age and a high amputation through the right leg this joint 



ivds quite normal. 



In contrast with the extended position (Fig. 177) this figure indicates the 

 relations during extreme flexion. As the section has been carried almost through 

 the middle of the joint, a larger part of the Intrinsic Ligaments is shewn than 

 in Fig. 177. 



As the Patella is fixed by the Ligament of the Patella to the Tibia, the 

 Patella leaves the Anterior Surface of the Femur during flexion, and comes to 

 lie in front of the Joint-slit, which it does not cover during extension. The Capsule 

 is folded backwards, and the Vessels and Nerves are extremely bent. To such 

 frequent bandings of an imperfect elastic arterial tube, is attributed the main cause 

 of the not-uncommon aneurysm of the Popliteal Artery. Of the 2 Crucial Ligaments, 

 the figure exhibits the Anterior : this extends from the depression in front of the 

 Spine of the Tibia (Anterior Intercondylar Fossa) upwards, outwards and back- 

 wards to the inner side of the External Condyle; its function, like the Posterior 

 Crucial Ligament, is to check excessive rotatory movements. The Plica Synovialis 

 Patellaris fills up the space between the Patella, Articular Surface of the Tibia, 

 and the Crucial Ligaments. 



One of the most striking changes which occurs in this joint during flexion, 

 is relaxation of the External Lateral Ligament — this is not seen in the figure — . 

 Attached to the Femur eccentric to the axis of flexion, this ligament becomes tense 

 during extension and prevents rotation, but during flexion it is relaxed and allows 

 inward rotation of the leg. These movements, however, are limited by the Crucial 

 Ligaments. A glance at the figure shews its complexity. Contrary to the other large 

 joints, which either have a free joint cavity or are at the outset traversed by one tendon 

 (e. g. Shoulder, by tendon of biceps. Hip-joint by Ligamentum Teres), the interior 

 of this joint contains a complicated arrangement of ligaments which lead to the 

 formation of numerous pouches. In cases of suppuration in the Knee-joint, the 

 purulent products, therefore, tend to remain in these recesses and clefts, and are 

 only removed with difficulty. 



