238 



SPECIAL ANATOMY OF THE SKELETON 



below, and convex from above downward, which articulates with a corresponding 

 surface on the outer side of the astragalus. Behind and beneath the articular 

 surface is a rough depression which gives attachment to the posterior fasciculus 

 of the external lateral ligament of the ankle. The anterior border is thick and 

 rough, and marked below by a depression for the attachment of the anterior 

 fasciculus of the external lateral ligament. The posterior border is broad and 

 marked by a shallow groove (sulcus malleolaris), for the passage of the tendons 

 of the Peroneus longus and brevis muscles. The apex is rounded, and gives 

 attachment to the middle fasciculus of the external lateral ligament. 



For 

 nstragalus 



Upper extremity. 



Appears about / 

 4th year. 



Unites about 

 25th year. 



For post, fascic. of 

 extl. lateral ligt. 



Appears at_ 

 2nd year. ~ 



Unites about 

 20th year. 



FIG. 189. Lower extremity of right fibula. 

 Internal aspect. 



Lower extremity. 



FIG. 190. Plan of the development of 

 the fibula. From three centres. 



In order to distinguish the side to which the bone belongs, hold it with the lower extremity 

 downward and the broad groove for the Peronei tendons backward i. e., toward the holder; 

 the triangular subcutaneous surface will then be directed to the side to which the bone belongs. 



Development. From three centres (Fig. 190) one for the shaft and one for each extremity. 

 Ossification commences. in the shaft about the eighth week of fetal life, a little later than in the 

 tibia, and extends gradually toward the extremities. At birth both ends are cartilaginous. Ossifi- 

 cation commences in the lower end in the second year, and in the upper one about the fourth 

 year. The lower epiphysis, the first in which ossification commences, becomes united to the 

 shaft about the twentieth year; the upper epiphysis joins about the twenty-fifth year. Ossifi- 

 cation appearing first in the lower epiphysis is contrary to the rule which prevails with regard 

 to the commencement of ossification in epiphyses viz., that epiphysis toward which the nutrient 

 artery is directed commences to ossify last; but it follows the rule which prevails with regard to 

 the union of epiphyses, by uniting first. 



Articulations. With two bones: the tibia and astragalus. 



Attachment of Muscles. To nine: To the head, the Biceps femoris, Soleus, and Peroneus 

 longus; to the shaft, its anterior surface, the Extensor longus digitorum, Peroneus tertius, and 

 Extensor proprius hallucis; to the internal surface, the Tibialis posticus; to the posterior surface, 

 the Soleus and Flexor longus hallucis, to the external surface, the Peroneus longus and brevis. 



Surface Form. The only parts of the fibula which may be fe't are the head and the lower 

 part of the external surface of the shaft and the external malleolus. The head may be seen 

 and felt behind and to the outer side of the outer tuberosity of the tibia. It presents a small, 

 prominent triangular eminence slightly above the level of the tubercle of the tibia. The exter- 



