746 MAMMALIAN ANATOMY 



tibial sides, the proximal part faces to the plantar, distal, and fibular 

 sides. The second facet lies on the tibial side between the deep oblique 

 groove and the tibial margin. It occupies the distal half of the body, 

 and is continued on the neck. It leaves a small, deeply depressed 

 surface of the body free at the tibio-proximal angle, continuous with 

 the oblique groove and under the short proximal margin. The artic- 

 ular facet is oval, gently convex in both directions, and articulates with 

 the facet on the dorsal surface of the lesser process of the calcaneum. 

 A narrow articular line is carried from it along the fibular margin of 

 the neck and joins a triangular facet at the proximo-fibular part of the 

 plantar surface of the head for articulation with the corresponding line 

 and anterior expansion on the tibial side of the distal part of the sur- 

 face of the calcaneum. The rest of the under surface of the head and 

 neck of the astragalus is convex. In the middle line is a deep oval 

 pit for the attachment of a ligament which runs to the plantar border 

 of the proximal surface of the scaphoid. 



Nomenclature. Astragalus is a Greek name for a die, and in the 

 earliest times the knuckle bones from sheep and goats were used as 

 dice. The Latin talus, with the same meaning, is also employed as a 

 name for this bone, particularly by European writers. In compara- 

 tive anatomy the astragalus is known as the tibiale. The Germans 

 translate astragalus into das Wurfelbein, or use the better term das 

 Sprungbein. The French synonym is I'astragale. 



Determination. If the bone be held with the dorsal or trochlear 

 surface upward and the head toward the student, the head will be on 

 the side to which the bone belongs. 



Articulation. The astragalus articulates with the tibia on the 

 dorsal and tibial sides, with the fibula on the dorsal and fibular sides, 

 with the calcaneum on the plantar side, and with the scaphoid dis- 

 tally. 



Muscular Attachment. To the dorsal surface of the astragalus 

 is attached a part of the extensor brevis digitorum. 



THE CALCANEUM. 



General Description. The Calcaneum is the largest bone of the 

 tarsus (Fig. 564). Its entire length and width show only on the 

 plantar surface of the foot ; its dorsal surface is partly covered by the 

 astragalus. It does not enter into the articulation of the ankle-joint. 



