Bones of the Lower Extremity. 141 



Facies articularis 

 anterior 



Facies articularis 

 media 



Sustentaculum , 

 tali 



Sulcus calcanei 



Facies articularis 

 posterior 



Corpus calcanei - 



Facies articularis 

 cuboidea 



188. Right heel bone, calcaneus, from above. 



The calcaneus (heel bone, 0. T. os calcis) (see also Figs. 189, 190, 198203) 

 is the largest tarsal bone, lies below the ankle bone and at the same time projects 

 beyond it behind. It possesses a quadrilaterally prismatic body, corpus calcanei, and 

 an anterior extremity. 



The corpus calcanei becomes thickened behind to form the tuber calcanei, from 

 which two rough broad projections pass downward, the processus medialis tuberis cal- 

 canei, and the processus later alls tuberis calcanei (see Fig. 201). The upper surface 

 has three articular surfaces covered with cartilage for the talus; about in its middle an 

 oblong, markedly convex, fades articularis posterior, in front and medianward two 

 smaller, almost flat, fades articular es media et anterior ; the latter are separated from 

 the posterior by a rough deep groove, sulcus calcanei; the middle rests upon a medially 

 projecting piece of bone, sustentaculum tali, which presents on its inferior surface a 

 groove, the sulcus m. flexoris halluds longi (for the tendon of the m. flexor hallucis 

 longus). The margin of this projection directed medianward is usually rough, sometimes, 

 however, partly smooth or hollowed out like a groove; on it glides the tendon of the 

 m. flexor digitorum longus on its way to the sole of the foot. On the lateral surface 

 of the heel bone there is often a small projection, processus trochlearis ; below which 

 runs a groove, the sulcus m. peronaei [longi] (for the tendon of the m. peronaeus 

 longus). The anterior surface of the calcaneus is directed also medianward, is quadri- 

 lateral with rounded corners, curved so as to be saddle-shaped and covered with cartilage 

 to form the fades articularis cuboidea (for the os cuboideum). The sulcus calcanei 

 and sulcus tali form together the sinus tarsi, a canal which, open lateralward, grows 

 markedly narrower as it extends medianward. 



