244 A MANUAL OF ANATOMY 



below the level of the upper surface of the head. It is divisible 

 into two nearly equal parts, upper and lower. The lower division 

 is rough, and is usually strongly ridged in the vertical direction 

 for the attachment of the ligamentum patellae. The upper division 

 is smooth, and is separated from that ligament by a synovial 

 bursa. 



The superior surface of the head presents the two condylar 

 articular surfaces, separated from each other by an irregular interval, 

 which, amongst other markings, presents the bifid tibial spine. 

 Each surface surmounts the corresponding lateral tuberosity. 

 The external condylar surface is broad from side to side, and is 

 almost circular. It is concave from side to side, and concavo- 

 convex from before backwards. Its cartilage rises towards the 

 middle line to coat the external surface of the outer tubercle of the 

 tibial spine, and posteriorly it dips down for a little on the outer 

 part of the back of the external tuberosity, where the tendon of 

 the popliteus glides over it. It is in this situation where the carti- 

 lage is occasionally continuous with that of the fibular facet. The 

 internal condylar surface is oval and concave, being elongated from 

 before backwards, but narrow from side to side. The cartilage of 

 this surface rises towards the middle line to coat the internal 

 surface of the inner tubercle of the tibial spine. Each condylar 

 surface is deepened by a semilunar fibro-cartilage, which is placed 

 round its peripheral part. 



The interspace between the condylar surfaces presents the 

 spine, which is distant from the posterior border about one-third 

 of the antero-posterior measurement. The spine is formed by an 

 upward rising of the contiguous borders of the condylar surfaces, 

 and is bifid, ending in two tubercles, of which the inner is the 

 better marked and longer of the two. The interspace between 

 these tubercles gives attachment to the posterior cornu of the 

 external semilunar fibro-cartilage, which continues to be attached 

 to a depression behind the outer tubercle. The surfaces of the 

 tubercles which face each other are free from cartilage, but the other 

 surfaces have each a cartilaginous covering. 



In front of the spine there is a rough depression where important 

 structures are attached as follows : in front of the outer tubercle 

 of the spine the anterior cornu of the external semilunar fibro- 

 cartilage is attached, and in front of the inner tubercle the anterior 

 crucial ligament is attached to the bone. At the extreme anterior 

 and inner part there is an impression for the anterior cornu of the 

 internal semilunar fibro-cartilage. On the outer side of the im- 

 pression for the anterior crucial ligament, and in front of that for 

 the anterior cornu of the external semilunar fibro-cartilage, there 

 is a depression which is partially occupied by a small collection 

 of fat. At its outer part, however, there is a groove which receives 

 a portion of the external semilunar fibro-cartilage in extension of 

 the knee-joint. The immediately adjacent portion of the external 

 condylar surface is specially facetted for the play of part of the 



