DISSECTING MAM AL. 



intercondylic notch, divide the articular surface into three 

 areas. The anterior area (trochlea) lies on the inferior surface 

 of the coalescence of the condyles ; it is convex vertically and 

 presents a shallow groove between two convex surfaces, of 

 which the outer is the wider, more prominent, and higher in 

 front. The posterior areas (condyloid, or tibial surfaces) are 

 convex and curve spirally round the under surfaces and pos- 

 terior extremities of the condyles. From below, the inner 

 condyloid surface is the narrower and is curved round a verti- 

 cal axis while the outer surface runs backward and slightly 

 outward. [228] 



Patella. This sesamoid bone lies in the Quadriceps extensor 

 tendon in front of the knee. It is somewhat triangular and 

 presents a projecting lower angle (apex) and a broad upper 

 edge (base) , which is divided by a transverse line into two areas, 

 anterior and posterior; the latter is triangular. The borders, 

 inner and outer, are curved; the anterior surface is convex. 

 A vertical ridge divides the posterior (femoral articular) sur- 

 face into two parts; the outer is the larger and slightly con- 

 cave; the inner is slightly concave vertically but plane, or con- 

 vex, transversely; on the inner edge of the inner area there 

 may be a third vertical area. The deep surface of the apex is 

 rough and irregular. [230] 



Tibia. The upper extremity is expanded and comprises the 

 tuberosities, spine, and tubercle. On the top of each tuber- 

 osity is an articular condyle; the inner is slightly concave, 

 has a well-defined edge, and is oval, with its long axis antero- 

 posterior; the outer is the smaller and rounder, slightly concave 

 transversely and convex antero-posteriorly, and has a sharp 

 edge which becomes rounded off behind. Between the con- 

 dyles is a prominence (spine) whose summit is grooved and 

 capped on either side by a prolongation (tubercle) of the con- 

 dyle; the inner tubercle is higher, longer, and less pointed than 

 the outer. Between the condyles, in front of and behind the 

 spine, are two V-shaped surfaces (intercondylic fossae); the 



[252] 



