J 24 TARSUS ASTRAGALUS CALCANEUS. 



taking place in the inferior epiphysis during the second year, and in tne 

 superior during the fourth or fifth. The inferior epiphysis is the first to 

 become united with the diaphysis, but the bone is not completed until 

 nearly the twenty-fifth year. 



Articulations. With the tibia and astragalus. 



Attachment of Muscles. To nine ; by the head, to the tendon of the 

 biceps and soleus; by the shaft, its external surface, to the peroneus 

 longus and brevis ; internal surface, to the extensor longus digitorum, 

 extensor proprius pollicis, peroneus tertius, and tibialis posticus ; by the 

 posterior surface, to the popliteus and flexor longus pollicis. 



TARSUS. The bones of the tarsus are seven in number ; viz. the astra- 

 galus, calcaneus, scaphoid, internal middle, and external cuneiform and 

 cuboid. 



The ASTRAGALUS (os tali) may be recognised by its rounded head, a 

 broad articular facet upon its convex surface, and two articular facets, 

 separated by a deep groove, upon its concave surface. 



The bone is divisible into a superior and inferior surface, an external 

 and internal border, and an anterior and posterior extremity. The supe- 

 rior surface is convex, and presents a large quadrilateral and smooth facet, 

 somewhat broader in front than behind, to articulate with the tibia. The 

 inferior surface is concave, and divided by a deep and rough groove (sul- 

 cus tali), which lodges a strong interoessous ligament, into two facets, the 

 posterior large and quadrangular, and the anterior smaller and elliptic, 

 which articulate with the os calcis. The internal border is flat and irre- 

 gular, and marked by a pyriform articular surface, for the inner malleolus. 

 The external presents a large triangular articular facet, for the external 

 malleolus, and is rough and concave in front. The anterior extremity 

 presents a rounded head, surrounded by a constriction somewhat resem- 

 bling a neck ; and the posterior extremity is narrow, and marked by a 

 deep groove, for the tendon of the flexor longus pollicis. 



Hold the astragalus with the broad articular surface upwards, and the 

 rounded head forwards ; the triangular lateral articular surface will point 

 to the side to which the bone belongs. 



Articulations. With four bones ; tibia, fibula, calcaneus, and sca- 

 phoid. 



The CALCANEUS (os calcis) may be known by its large size and oblong 

 figure, by the large and irregular portion which forms the heel, and by two 

 articular surfaces, separated by a broad groove upon its upper side. 



The calcaneus is divisible into four surfaces, superior, interior, external, 

 and internal ; and two extremities, anterior and posterior. The superior 

 surface is convex behind and irregularly concave in front, where it pre- 

 sents tw r o, and sometimes three articular face-is, divided by a broad and 

 shallow 7 groove (sulcus calcanei), for the interosseous ligament. The in- 

 ferior surface is convex and rough, and bounded posteriorly by the two 

 inferior tuberosities, of which the internal is broad and large, and the ex- 

 ternal smaller and prominent The external surface is convex and sub- 

 cutaneous, and marked towards its anterior third by two grooves, often 

 separated by a tubercle, foi the tendons of the peroneus longus and brevis 

 The internal surface is concave and grooved, for the tendons and vessels 

 which pass into the sole of the foot. At the anterior extremity of A liis 



