THE FIBULA 



articular facet of the lateral malleolus. It serves for the attachment of the inter- 

 osseous membrane, which separates the Extensor muscles in front from the Flexor 

 muscles behind. 



The postero-lateral border is prominent; it begins above at the apex, and ends 

 below in the posterior border of the lateral malleolus. It is directed lateralward 

 above, backward in the middle of its course, backward, and a little medialward 

 below, and gives attachment to an aponeurosis which separates the Peronsei on 

 the lateral surface from the Flexor muscles on the posterior surface. 



The postero-medial border, sometimes called the oblique line, begins above at the 

 medial side of the head, and ends by becoming continuous with the interosseous 

 crest at the lower fourth of the bone. It is well-marked and prominent at the upper 

 and middle parts of the bone. It gives attachment to an aponeurosis which sep- 

 arates the Tibialis posterior from the Soleus and Flexor hallucis longus. 



Upper extremity 



Appears about 

 4.th year 



Unites about 

 25th year 



For posterior 

 talofibular ligt. 



Appears at 

 2nd year 



Unites about 

 20th year 



FIG. 262. Lower extremity of right fibula. 

 Medial aspect. 



Lower extremity 



Fia. 263. Plan of ossification of the 

 fibula. From three centers. 



Surfaces. The anterior surface is the interval between the antero-lateral and 

 antero-medial borders. It is extremely narrow and flat in the upper third of its 

 extent; broader and grooved longitudinally in its lower third; it serves for the 

 origin of three muscles : the Extensor digitorum longus, Extensor hallucis longus, 

 and Peronseus tertius. 



The posterior surface is the space included between the postero-lateral and the 

 postero-medial borders; it is continuous below with the triangular area above 

 the articular surface of the lateral malleolus; it is directed backward above, back- 

 ward and medialward at its middle, directly medialward below. Its upper third 

 is rough, for the origin of the Soleus; its lower part presents a triangular surface, 

 connected to the tibia by a strong interosseous ligament; the intervening part of 

 the surface is covered by the fibers of origin of the Flexor hallucis longus. Near 

 the middle of this surface is the nutrient foramen, w r hich is directed downward. 



The medial surface is the interval included between the antero-medial and the 

 postero-medial borders. It is grooved for the origin of the Tibialis posterior. 



