BONES OF LOWER LIMB 45 



position is placed obliquely i.e., the upper extremities being 

 widely separated by the pelvis while the lower extremities are 

 in apposition to one another, the inferior surfaces normally 

 are in the same horizontal plane ; whereas if the femur is held 

 vertically, the inner condyle projects downwards below the 

 outer one. The inner surface of the inner condyle and the 

 outer surface of the outer condyle are subcutaneous, and each 

 possesses a pronounced tuberosity for the attachment of 

 ligaments. 



The Inferior Surface of the femur is cartilage covered for 

 articulation with the head of the tibia. It is more or less 

 crescentic in form, the convexity being forwards. The anterior 

 part is called the trochlea, and articulates with the patella. 

 The inferior surfaces of the condyles are convex in both direc- 

 tions. That of the outer one is wider than the inner, and 

 rises to a higher, point on the anterior surface of the shaft. 

 They each articulate with the tibia by means of a meniscus 

 of cartilage, which separates the bones from one another. 



Ossification. There is one primary centre for the shaft before 

 birth, secondary centres appearing for the head, trochanter and 

 lower extremity. (This latter may appear just before birth.) 

 The whole bone is fused together by the twenty-second year. 



The Patella is the largest sesamoid bone in the body, and 

 is formed in the tendon of the quadriceps extensor in front 

 of the knee-joint. It is triangular in shape, with the apex 

 downwards. The anterior surface of the bone is slightly convex . 

 The posterior surface is much more rounded, and has a ridge 

 which divides it into two parts longitudinally, of which the 

 inner one is the smaller. This ridge glides between the two 

 condyles of the femur. 



Ossification. The patella does not begin to ossify till about 

 the third year, and is complete at puberty. 



The Tibia is the inner bone of the leg. It is a long bone 

 with a shaft and two extremities, and articulates above with 

 the condyles of the femur and the upper end of the fibula ; 

 below, with the lower end of the fibula and one tarsal bone, the 

 astragalus. 



The Upper Extremity is much expanded, and forms two 



