OSTEOLOGY 





The lateral surface is the space between the antero-lateral and postero-lateral 

 borders. It is broad, and often deeply grooved; it is directed lateralward in the 

 upper two-thirds of its course, backward in the lower third, where it is continuous 

 with the posterior border of the lateral malleolus. This surface gives origin to 

 the Peronsei longus and brevis. 



The Lower Extremity or Lateral Malleolus (malleolus lateralis; distal extremity; 

 external malleolus). The lower extremity is of a pyramidal form, and somewhat 

 flattened from side to side; it descends to a lower level than the medial malleolus. 

 The lateral surface is convex, subcutaneous, and continuous with the triangular, 

 subcutaneous surface on the lateral side of the body. The medial surface (Fig. 

 262) presents in front a smooth triangular surface, convex from above downward, 

 which articulates with a corresponding surface on the lateral side of the talus. 

 Behind and beneath the articular surface is a rough depression, which gives attach- 

 ment to the posterior talofibular ligament. The anterior border is thick and rough, 

 and marked below by a depression for the attachment of the anterior talofibular 

 ligament. The posterior border is broad and presents the shallow malleolar sulcus, 

 for the passage of the tendons of the Peronsei longus and brevis. The summit 

 is rounded, and give attachment to the calcaneofibular ligament. 



Ossification. The fibula is ossified from three centers (Fig. 263) : one for the body, and one 

 for either end. Ossification begins in the body about the eighth week of fetal life, and extends 

 toward the extremities. At birth the ends are cartilaginous. Ossification commences in the 

 lower end in the second year, and in the upper about the fourth year. The lower epiphysis, 

 the first to ossify, unites with the body about the twentieth year; the upper epiphysis joins 

 about the twenty-fifth year. 



Groove for Peronceus longus 



Trochlear process 



Middle articular surface 

 Anterior artic. surface 

 Post, artic. surface 



Trochlear process 



For cuboid bone 

 For attachment 



of plantar calcaneo- 

 cuboid ligament 



Sustentaculum 

 tali 



Sustentaculum 

 tali 



Sulcus calcanei 



Tuberosity 

 Fid. 264. Left calcaneua, superior surface. 



Sulcus for Flexor 

 hattucis longus 



Medial process 



Tuberosity ' 



Lateral process 

 FIG. 265. Left calcaneus, inferior surface. 



THE FOOT. 



The skeleton of the foot (Figs. 268 and 269) consists of three parts: the tarsus, 

 metatarsus, and phalanges. 



