102 OSTEOLOGY, OR ANATOMY OF OSSEOUS SYSTEM 



The inferior surfaces of the two condyles are on the same 

 level in the natural position of the femur. Opposite in front 

 of the intercondylar notch the whole articular surface is divided 

 by a faint transverse groove on either side into three parts 

 a convex surface on either condyle for the tibia and a grooved 

 anterior surface for the patella. 



The patellar surface is trochlear in form, marked by a vertical 

 hollow and two lips; the external portion is wider, more prom- 

 inent, and rises higher. The tibial surfaces are nearly parallel, 

 but the internal one turns outward anteriorly to meet the 

 patellar surface. The exposed lateral surface of each condyle 

 presents a tuberosity or epicondyle for ligamentous attachment. 

 The external is the smaller; above it is the impression for 

 the outer head of the gastrocnemius ; below and behind it is 

 an oblique groove ending inferiorly in a pit from which rises 

 the popliteus muscle; its tendon sinks fully into the groove 

 only when the knee-joint is flexed. The inner head of the 

 gastrocnemius rises from the upper part of the inner condyle. 



The intercondylar fossa presents two impressions for crucial 

 ligaments; that for the anterior ligament is on the posterior 

 part of the inner surface of the external condyle; that for the 

 posterior ligament is on the forepart of the external surface 

 of the inner condyle. 



The angle of the neck with the shaft is open in the fetus and 

 child, then lessens under the weight of the body, but under- 

 goes no change after growth is completed. The upper part 

 of the gluteal ridge may form a third trochanter. 



The Patella 



The patella, or knee-pan, is a sesamoid bone developed 

 in the tendon of the quadriceps extensor cruris. It is some- 

 what triangular, with its apex below. Its anterior surface 

 is convex and striated, and pierced by vascular foramina. 

 The superior border is broad and sloped from behind down- 

 ward and forward, and gives attachment to the rectus and 

 crureus portions of the quadriceps extensor. 



The posterior surface of the bone presents two vertical and 

 two transverse ridges; one vertical ridge is close to the inner 

 margin; the other is distinct and divides the surface into two 

 parts, the external of which is the larger and transversely 

 concave, the inner smaller portion is convex. 



