Synovial Membrane of Knee 473 



The inter-articular fibro -cartilages are attached by their 

 cornua in front of, and behind the tibial spine, and their convex borders 

 are connected with the margin of the tuberosities of the tibia by short, 

 vertical fibres, which constitute the coronary ligament. The in- 

 ternal semilunar cartilage is firmly connected with the internal lateral 

 ligament, but the outer disc is separated from the external lateral liga- 

 ment by the tendon of origin of the popliteus which lies in a groove 

 upon it. The inner cartilage is, therefore, far less movable than the 

 outer ; still, if one of the discs become loosened and interfere with 

 the working of the joint, it is most likely the inner. I cannot explain 

 this paradox, except on the theory that the outer one is so movable 

 that it escapes injury from a wrench 

 which loosens the inner. Both sur- 

 faces of the semilunar cartilages are 

 covered with synovial membrane. 



The synovial membrane, the 

 largest in the body, lines the capsule, 

 and, having ascended as a pouch for 

 about the width of four ringers, be- 

 neath the quadriceps, turns down over 

 the front of the femur. It forms also 

 shallow pouches on either side of the 

 patella and its ligament, and sends 

 a collar round the tendon of the pop- 

 liteus as it passes out of the joint. 

 A cushion of fat intervenes between 

 the ligamentum patella? and the mem- 

 brane which, in that region, sends a 

 pouch on to the crucial ligaments 

 (ligamentum mucosum) ; the free 

 borders of this pouch are the liga- 

 menta alaria. In the neighbourhood 

 of the crucial ligaments the membrane 

 has rudimentary fringes. When the 

 knee is extended, the top of the syno- 

 vial pouch is drawn up by the sub- 

 crureus working in harmony with the 

 crureus. This part of the cavity is apt 

 to communicate with a bursa higher 

 up the shaft of femur under the quad- 

 riceps ; that bursa may suppurate 

 without the membrane of the knee 

 being implicated. 



It is sometimes remarked that, because the synovial pouch ascends 

 higher under the crureus when the knee is extended, one ought to keep 

 the limb bent in operating upon the front of the femur near the joint. 



Vertical section of knee of young sub- 

 ject. (After THOMSON, from QUAIN.) 

 i, i, synovial membrane ; 2, lig. 

 mucosum ; 3, lig. patellae with, 4, 

 bursa behind it ; 5 and 6, crucial ligts. 

 Bursae are also shown in front of 

 tubercle of tibia, in front of patella, 

 and beneath crureus (z>. p. 478). 



