TIBIA. 



165 



THE TIBIA. 



The Tibia (so named from its 

 resemblance to a flute or pipe) is 

 situated at the front and inner 

 side of the leg, and, excepting the 

 femur, is the longest and largest 

 bone in the skeleton. It is pris- 

 moid in form, expanded above, 

 where it enters into formation 

 with the knee-joint, more slightly 

 enlarged below. In the male, its 

 direction is vertical, and parallel 

 with the bone of the opposite side ; 

 but in the female it has a slight 

 oblique direction downwards and 

 outwards, to compensate for the 

 oblique direction of the femur 

 imvards. It presents for exami- 

 nation a shaft and two extremi- 

 ties. 



The Upper Extremity or head 

 is large and expanded on each, 

 side into two lateral eminences, 

 the tuberosities. Superiorly, 

 the tuberosities present two 

 smooth concave surfaces, which 

 articulate with the condyles of 

 the femur; the internal articular 

 surface is longer than the ex- 

 ternal, oval from before back- 

 wards, to articulate with the 

 internal condyle; the external 

 one being broader, flatter, and 

 more circular, to articulate with 

 the external condyle. Between 

 the two articular surfaces, and 

 nearer the posterior than the 

 anterior aspect of the bone, is an 

 eminence, the spinous process of 

 the tibia, surmounted by a pro- 

 minent tubercle on each side, 

 which give attachment to the 

 extremities of the semilunar 

 fibre-cartilages ; and in front and 

 behind the spinous process, a 

 rough depression for the attach- 

 ment of the anterior and poste- 

 rior crucial ligaments and the 

 semilunar cartilages. Anteriorly 

 the tuberosities are continuous 

 with one another, presenting a 

 large and somewhat flattened 

 triangular surface, broad above, 

 and perforated by large vascular 

 foramina; narrow below, where 

 it terminates in a prominent 



Fig. 109. Bones of the Right Leg. Anterior Surface. 



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Btylel* preet,. 



FIBULA 



