APPLIED ANATOMY. 



Semilunar Cartilages, Coronary and Transverse Ligaments. The semilunar 

 cartilages are used to deepen the joint in the same manner as the cotyloid of the hip 

 and glenoid of the shoulder. It is their method of attachment that is important. The 

 external is nearly circular, the internal is semi-elliptical. The ends are fibrous and 

 are attached in front of and behind the spine of the tibia. The transverse ligament 

 is a band passing across the front from one semilunar cartilage to the other (Fig. 

 549). As Macalister has pointed out, there is no true coronary ligament. It is 

 the part of the capsular ligament running from the semilunar cartilages to the tibia. 



The semilunar cartilages are attached by their outer edges to the capsular liga- 

 ment. This attachment is less in extent in the case of the external, because its 

 outer surface is obliquely grooved by the tendon of the popliteus muscle, but it has 

 an additional attachment in the ligament of Wrisberg, as stated under the posterior 



crucial ligament. Humphry ( ' ' Hu- 

 man Skeleton, ' ' 546) has pointed out 

 that the semilunar cartilages in flexion 

 and extension move with the tibia, but 

 in pronation and supination (rotation) 

 move with the femur. 



Ligamenta Alaria and Muco- 

 sum. Below the patella is a pad of 

 fat extending under the upper portion 

 of the tendo patellae ; a bursa is under 

 the lower portion. Passing up from 

 this pad to the intercondyloid notch 

 and crucial ligaments is the ligamen- 

 tum mucosum; below, it is continu- 

 ous with the synovial fringes at each 

 side of the lower edge of the patella 

 which form the ligamenta alaria. 

 We would suggest that it is possible 

 that these ligaments perform for the 

 knee-joint what Allis has suggested 

 the ligamentum teres does for the hip, 

 viz. : act as a swab to distribute the 

 synovia over the articular surfaces. 



Bursae of the Knee. There 

 are a number of bursae about the 

 knee-joint, but they are not all of im- 

 portance. Anteriorly there are the 

 prepatellar, suprapatellar, and deep 

 and superficial infrapatellar. 



The prepatellar bursa lies in the 

 subcutaneous tissue between the skin 

 and patella. It is often enlarged, con- 

 stituting "housemaid's knee" (Fig. 

 550). The bursa is almost always 



present, but often irregular in shape and character. Injuries frequently cause it to 

 inflame, as do also rheumatoid affections. Sometimes the tendon of the quadriceps 

 over the patella is ossified clear to the surface, which is often irregular and rough, 

 and is felt immediately beneath the skin with apparently no subcutaneous tissue 

 intervening. In these cases the bursa may be very irregular or loculated in shape, 

 or there may be more than one. The sac of the bursa is usually very thin, but be- 

 comes thick and distinct as the result of irritation. Excision is usually the quickest 

 way of curing housemaid's knee, but often the easier way of simple incision and 

 drainage with a wick of gauze is sufficient. 



The suprapatellar or subfemoral bursa extends from 5 to 7.5 cm. (2 to 3 in. ) 

 above the patella beneath the crureus muscle. It is liable to be injured by stabs or 

 punctures, and thereby infect the joint with which it communicates in 8 out of 10 

 cases. It becomes distended in intra-articular effusions. 



Subfemoral 

 bursa 



Ridge on 

 patella 



Ligamentum 

 alaria 



Ligamentum 

 mucosum 

 Transverse 

 ligament 

 Internal semi- 

 lunar cartilage 

 External semi- 

 lunar cartilage 

 Anterior cru- 

 cial ligament 



Posterior cru- 

 cial ligament 



Popliteus 



Head of fibula 



Semimem- 

 branosus 



FIG. 549. View of the interior of the knee-joint, looking 

 forward. 



