140 



Bones of the Lower Extremity. 



Facies articularis navicularis 



i 



Facies articularis 

 calcanea anterior \ 



Caput tali- - 

 Sulcus tali 



Facies articularis 

 calcanea media 



Processus 

 ateralis tali 



Facies articularis - 

 calcanea posterior 



Articular surface 



for the fibrocarti- 



lago navicularis 



Facies articularis navicularis 



. Caput tali 



. Collum tali 



Processus posterior tali 



Sulcus 

 m. flexoris hallucis longi 



Processus 



lateralis 



tali 



Trochlea tali 



Sulcus m. flexoris 

 hallucis longi 



Processus posterior tali 



186 and 187. Right ankle bone, talus (0. T. astragalus). 



From below. From above. 



The tarsus (root of the foot) (see also Figs. 198 203 and 271) is composed of the 

 seven ossa tarsi : talus calcaneus, os naviculare pedis, ossa cuneiformia primum, secundum, 

 tertium, os cuboideum; the four last mentioned lie distal ward close to one another; the three 

 first mentioned proximalward partly over one another, so that the bones of the leg are 

 not united with several bones of the tarsus, but only with that situated uppermost, namely, 

 the talus. 



The talus (ankle bone} (0. T. astragalus) (see also Figs. 198203) is divisible into 

 a body, corpus tali, and a head, caput tali, attached in front ; between the two lies a con- 

 stricted part, the collum tali. 



The corpus tali supports on its upper surface the broad trochlea tali; this is somewhat 

 broader in front than behind, is covered with cartilage above, fades superior, curved so as 

 to be markedly convex from before backward and slightly concave in transverse direction; it 

 possesses a large, triangular, lateral surface, fades malleolaris lateralis (see Fig. 198) covered 

 with cartilage, from which a process, processus lateralis tali, passes off lateral ward and down- 

 ward ; the medial surface of the trochlea has above only a narrow fades malleolaris medialis 

 (see Fig. 199); it is covered with cartilage. The lower surface of the ankle bone possesses three 

 articular surfaces, covered with cartilage, for the calcaneus : a posterior, largest, markedly con- 

 cave, fades articularis calcanea posterior, as well as (separated therefrom by a deep, rough 

 groove, sulcus tali) two nearly flat, smaller, fades articulares calcaneae media et anterior, 

 of which the most anterior lies upon the caput tali. On the posterior margin of the body 

 a blunt process, processus posterior tali, is visible which is divided by a groove, sulcus m. 

 flexoris hallucis longi (for the tendon of the m. flexor hallucis longus) into a smaller, medial 

 and a larger, lateral projection; the latter is sometimes an independent bone (os trigonum) 

 and then is connected by connective tissue only with the remaining bone (it is not shown in the 

 figure). The head presents in front an oval, transversely directed, markedly convex articular 

 surface, fades articularis navicularis (for the os naviculare); adjacent to this, below and 

 medianward, is another oblong surface for the lig. calcaneonaviculare plantare, or the fibro- 

 cartilago navicularis. 



