THE KXEE-JOIXT. 155 



external articular vessels. The tendon of the biceps flexor cruris muscle 

 is frequently divided into two by this ligament, and between the ligament 

 and the tendon there is a synovial bursa. Further back is another baud, 

 the short external lateral ligament, the arrangement of which is more variable, 

 often connected with the tendon of the popliteus muscle, and occasionally 

 terminating in the capsular membrane. 



The posterior ligament is a flat fasciculus of fibres passing from behind 

 the inner tuberosity of the tibia upwards and outwards to the external 

 condyle of the femur, and is in part continuous at its inner end with the 

 tendon of the semimembrauosus muscle. 



The ligamentum patella is a strong flat band, of a tendinous nature, 

 attached superiorly to the lower extremity of the patella, and the 

 depression beneath its articular surface, and inferiorly to the anterior 

 tubercle of the tibia. Between the tibia and the ligament, near its insertion, 

 is placed a synovial bursa. If the patella be considered a sesamoid bone, this 

 ligament may be regarded as part of the tendon of the rectus femoris muscle. 



The crucial ligaments, placed in the centre of the joint, pass from the 

 sides of the intercondyloid fossa to the spaces in front of and behind the spine 

 of the tibia. They decussate somewhat like the lines of the letter X. The 

 anterior or external ligament is fixed by its lower extremity to the inner 

 part of the pit before the spine of the tibia, and by its upper extremity it 

 is inserted into the inner and hinder part of the external condyle of the 

 femur ; hence its direction is upwards, backwards, and outwards. The 

 posterior or internal ligament is attached inferiorly to the back of the pit 

 behind the tibial spine, and superiorly to the fore part of the intercondyloid 

 hollow, as well as slightly to the side of the inner condyle of the femur ; its 

 fibres are directed upwards and a little forwards. 



The semilunar cartilages are two crescent-shaped iuterarticular fibro- 

 cartilages, placed on the articulating surfaces of the head of the tibia, and 

 interposed between these and the condyles of the femur. They have each a 

 synovial surface above and below, and a convex border, which is thick, 

 while the concave border is thinned to a fine edge, and the part of the 

 articular surface of the tibia within the concave border of each cartilage is 

 left uncovered. At their extremities they are fibrous, and are firmly fixed 

 to the head of the tibia, whilst by the circumference they are connected 

 with the fibrous capsule of the joint. 



Fig. 142. VIEW OP THE INTERARTICULAR FIBRO- Fig. 142. 



CARTILAGES OP THE RIGHT KNEE-JOINT, PROM 

 ABOVE, AS THEY LIE ON THE UPPER SURFACE 



OP THE TlBIA, WITH THE CRUCIAL LlGAMENTS 

 DIVIDED, AND THE LlGAMENTUM PATELL.E TURNED 

 FORWARDS. ^ 



1, ligamentum patellae ; 2, the inner, or semicircular 

 fibre -cartilage ; 3, the outer, or nearly circular one ; 

 4, is placed above the anterior tuberosity of the tibia 

 in front of the transverse ligament ; 5, the cut end 

 of the anterior crucial ligament directed obliquely 

 towards the outer side and backwards; 6, the cut 



end of the posterior crucial ligament, from which fibres are seen descending to the outer 

 fibro-cartilage ; b'', tibial attachment of the posterior crucial ligament; 7, the head of 

 the fibula; 8, the synovial surface of the tibia, which extends for some way downwards 

 towards the tibio-fibular synovial sac, with which it is sometimes continuous. 



The internal semilunar cartilage, elongated from before backwards, is 

 nearly of a semicircular form: its anterior cornu is small and pointed, and 

 is inserted into an impression at the fore and outer part of the internal 



