TIBIA. FIBULA. 



105 



jecting farther downwards than the anterior; internally the cartilaginous 

 surface is continued down in a vertical direction upon the internal malleolus, 

 clothing its outer surface somewhat more deeply in front than behind. The 



Fig. 97. RIGHT TIBIA PROM BEHIND. ^ Fig. 97. 



6, and 9, as in the preceding figure ; 2', groove behind 6 



the internal tuberosity for the tendon of the semi-mem- 

 branosus muscle ; 10, inclined articular facet below and 

 behind the outer tuberosity for the head of the fibula ; 

 11, oblique line of tibia, above which is the triangular 

 popliteal surface ; 12, foramen directed downwards for 

 the nutritious or medullary vessels ; 13, triangular rough 

 surface for the lower interosseous ligament and small 

 cartilaginous surface below it for articulation with the 

 fibula; 14, below a slight groove marking the place of 

 the flexor longus pollicis muscle ; 15, below the groove 

 of the tendons of the flexor communis digitorum and 

 tibialis posticus muscles, behind the malleolus internus. 



-12 



external surface, slightly concave, is rough 

 superiorly for ligament, and smooth below for 

 articulation with the fibula. The posterior sur- 

 face is marked by a double groove on the in- 

 ternal malleolus for the tendons of the tibialis 

 posticus and flexor longus digitorum, and more 

 externally by a slight depression where the flexor 

 longus pollicis lies; the inner surface of the 

 internal malleolus is subcutaneous. 



The tibia is slightly twisted, so that when the 

 internal malleolus is directed inwards, the in- 

 ternal tuberosity is inclined backwards a con- 

 formation which deserves attention in the 

 diagnosis and adjustment of fractures. 



THE FIBULA. 



The fibula, or peroneal bone, is situated at the 

 external side of the leg : it is nearly equal to 

 the tibia in length, but is much more slender. 

 Its inferior extremity is placed a little in advance 

 of the upper; and its shaft is slightly curved, 

 so as to have the convexity directed backwards, 

 and, in the lower half, slightly inwards towards 

 the tibia. 



The superior extremity, or head, somewhat ^|I^U 



expanded, presents a small oval cartilaginous 

 surface looking upwards and inwards, which 

 articulates with the external tuberosity of the 

 tibia, and externally to this a rough prominence directed upwards, to 

 which the tendon of the biceps muscle is attached: its external surface is 

 subcutaneous ; the rest is rough for ligaments. 



The inferior extremity or external malleolus, is larger than the head of 

 the bone, and longer and more prominent than the internal malleolus ; 

 internally it forms the outer limit of the ankle joiut, and presents a triangular 

 smooth surface for articulation with the astragalus, bounded posteriorly by 

 a rough depression where the transverse ligament is attached : its anterior 



