728 MAMMALIAN ANATOMY 



The posterior-external surface presents a median vertical depression 

 limited in front and behind by an eminence. The depression occupies 

 nearly the middle third of the surface. It is narrow above, often not 

 reaching the proximal margin, and wide below, where it passes out 

 on the shaft of the bone ; it varies greatly in depth, but is always 

 roughened for the attachment of the tibio-fibular ligament. The ante- 



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rior eminence is lozenge-shaped, and faces outward, backward, and 

 upward. Its upper part is roughened for the attachment of a tibio- 

 fibular ligament ; its lower part presents a smooth facet on which is 

 inserted the external ligament from the femur. The lower part of 

 this facet, with the eminence itself, is embraced by the upper end of 

 the area of origin of the peroneus longus muscle. This eminence is 

 sometimes called the styloid process of the fibula, The eminence 

 behind the median depression varies considerably in form, but is 

 usually oblong and convex ; its long axis is directed downward and 

 backward, while the eminence as a whole faces outward and back- 

 ward. It gives attachment by its upper edge to the tibio-fibular 

 ligament and for most of its extent to the tendon of origin of the 

 soleus muscle. From its lower end arises, externally, the posterior- 

 external border of the shaft, and, internally, the posterior-internal 

 border. 



The anterior-internal surface of the head of the fibula (Fig. 555) 

 has the same outline and the same borders as the posterior-external 

 surface. Its upper margin is bevelled in front and incised behind. 

 Below the articular facet of the proximal surface the surface is rough 

 and gives attachment to the tibio-fibular ligament and the proximal 

 part of the tibialis posticus muscle. The peroneus longus is attached 

 along the anterior-superior border and on the prominent anterior 

 angle, below which arises the upper part of the tibialis anticus. The 

 posterior half of the surface slopes outward above, and is rough and 

 slightly concave ; it affords attachment to the soleus behind, the flexor 

 longus digitorum above, and the flexor longus hallucis below. 



The proximal surface of the head (Fig. 555) is little more than 

 a border. It curves from in front backward and inward. Its anterior 

 half bears an oblong facet which faces inward, upward, and backward, 

 is covered with cartilage, and articulates with the facet on the lower 

 side of the external tuberosity of the tibia. The facet is subject to 

 considerable variation in size and extent: it sometimes occupies the 



