PELVIC LIMBS 



723 



border is prominent as far down as the articular surface for the fibula. 

 The outer border of the head may lack the groove for the extensor 

 longus digitorum muscle. 



HUMAN TIBIA. 



The human tibia (Fig. 550) is shorter than the femur. 

 Compared with the tibia of the cat, the anterior border of the 

 shaft is sharper but not so prominent in its upper part ; hence the 



antero-posterior diameter of 



the bone is distinctly re- 

 duced. 



The external, or interos- 



seous, border is well marked ; 



its upper part is nearer the 



anterior border than in the 



cat, therefore the upper part 



of the external surface is 



narrower. To the greater 



part of the external surface 



is attached the tibialis anticus 



muscle. 



The posterior surface 



(Fig. 551) is not so deeply 



concave above as is the cor- 

 responding surface of the 



cat's tibia. It presents the 



oblique, or popliteal, line 



passing from the external 



border downward and in- 

 ward to the internal border. 

 The line affords attachment to the soleus muscle ; 



ridge; 11, head of the fibula; 



above the line is inserted the popliteus. The 12, subcutaneous surface at the 



lower part of the bone; 13, 



region below the line is divided into two areas external maiieoius; 14, groove 



for tendons. 



by a convex longitudinal line which fades out 

 below on the external border. The external narrower area is for 

 the tibialis posticus ; the internal larger area is for the flexor longus 

 digitorum and flexor longus hallucis muscles. 



The internal border is well defined, although rounded. 



LEFT TIBIA AND FIBULA, 

 ANTERIOR VIEW. 



1, shaft of the tibia; 2, 3, 

 tuberosities ; 4, spine; 5, tu- 

 bercle; 6, crest or shin; 7, 

 lower extremity of the bone; 

 8, internal malleolus; 9, shaft 

 of the fibula; 10, its head; 

 11, external malleolus. 



RIGHT TIBIA AND FIBULA, 

 POSTERIOR VIEW. 



1, 2, articular surfaces of the 

 tibia for the condyles of the 

 femur, separated by the tibial 

 spine ; 3, the inner tuberosity ; 

 4, surface occupied by the pop- 

 liteal muscle, defined by the 

 popliteal line, 5; 6, nutrient 

 foramen; 7, surface covered 

 by the flexors of the toes; 8, 

 internal malleolus; 9, grooves 

 for tendons; 10, interosseous 



