PATELLA. TIBIA. 103 



The tibial surfaces are nearly parallel, except in front, where the internal 

 turns obliquely outwards to reach the patellar surface. Above the condyles 

 are two rough tuberosities, one on each side of the bone, which give attach- 

 ment to the external and internal lateral ligaments of the knee joint. 

 Between the external tuberosity and the back part of the external condyle 

 is a smooth groove directed downwards and forwards, and ending anteriorly 

 in a pit, in which the popliteus muscle takes origin. 



In the female the angle made by the neck of the femur with the shaft is less 

 obtuse than in the male; and from the greater width of the pelvis, and the shortness 

 of the limbs, the convergence of the thigh bones inferiorly is more apparent. 



THE PATELLA. 



The patella, rotula, or knee-pan, is situated at the front of the knee 

 joint, is attached inferiorly by a ligament or tendon to the tibia, and may be 



Fig. 95. RIGHT PATELLA. ^ Fj g> 95. 



A from before ; B from behind. 



Both views show the lower extremity pointing slightly inwards ; 

 the posterior view shows the articular cartilaginous surface, divided 

 by an elevated ridge into a smaller internal and a larger external 

 part. 



considered as a sesamoid bone developed in the tendon of 



the quadriceps extensor cruris. It is compressed from 



before backwards, and has the form of a triangle with the 



apex below. Its anterior surface is subcutaneous; its 



superior border is broad, and gives attachment to the 



extensor muscles; its inferior angle, together with a 



rough depression on its deep aspect, gives attachment to 



the ligainenturn patellae. The deep surface, except at the 



inferior angle, is coated with cartilage for articulation with 



the femur, and is divided by a vertical elevation into two 



parts, the external of which is the larger and is transversely concave, while 



the internal is convex. 



THE TIBIA. 



The tibia, or shin bone, is, next to the femur, the longest bone in the 

 skeleton. It is the anterior and inner of the two bones of the leg, and 

 alone communicates the weight of the trunk to the foot. It articulates with 

 the femur, fibula, and astragalus. 



The superior extremity is thick and expanded, broader from side to side 

 than from before backwards, and slightly hollowed posteriorly. On its 

 superior aspect are placed two slightly concave articular surfaces, which 

 sustain the femur. These are the condyloid surfaces; they are oval in form, 

 the external being widest transversely, and the internal longest from 

 before backwards. Between them is an irregular interval, depressed in 

 front and behind, where it gives attachment to the crucial ligaments 

 and semilunar cartilages of the knee joint, and elevated in the middle, 

 where is formed the spine. The summit of the spine presents two 

 prominent tubercles, which are formed by the prolongation upwards on 

 its sides of the margins of the condyles ; that of the outer coudyle being 

 turned slightly forwards, and that of the inner more slightly backwards. 

 On the sides of the upper extremity of the bone are two rounded 

 eminences, the external and internal tuber osities the outer one of these, 



