26 



ANATOMY FOK NQKSES. 



[CHAP. IV. 



bone is flattened from before backwards into a broad articular 

 surface, which is divided by a slight ridge into two parts, by 

 means of which it articulates with the ulna 

 and radius. 



The ulna (elbow bone) is placed at the 

 inner side of the forearm, parallel with the 

 radius. Its upper extremity presents for 

 examination two large curved processes and 

 two concave cavities; the larger process 

 forms the head of the elbow, and is called 

 the olecranon process. The lower extremity 

 of the ulna is of small size, and is excluded 

 from the wrist by a piece of fibro-cartilage. 

 The radius is situated on the outer side 

 of the forearm. The upper end is small 

 and rounded with a shallow depression on 

 FIG. is. THE ULNA its upper surface for articulation with the 

 AND RADIUS, i, radms; h unierus an( J a prominent ridge about it, 



2, ulna; o, olecranon ..,.,'. , ., ;, - , . , 



process, on the anterior like the head oi a nail, by means ot winch 

 surf ace of which are seen it rotates w i t hin the lesser sigmoid cavity 







the large (gs) and the 



small (Is) cavities, for of the ulna. 



The 



of the head of the radius, dius is large, and 

 radiuf^ 5 A> ^^ f formS the Chief P art 



of the wrist. 



Each metacarpus is formed by five 

 bones. These metacarpal bones are 

 curved longitudinally, so as to be con- 

 vex behind, concave in front ; they ar- 

 ticulate by their bases with the bones of 

 the wrist and with one another, and the 

 heads of the bones articulate with the 

 phalanges. 



The phalanges, or digits, are the bones FTG - 10.- BUNKS 



_ . WRIST AND HAND. 



of the lingers; they are fourteen in me taearpal bones ; pi, p, J>, 

 number (in each hand), three for each phalanges; 3, bones of the 



wrist. 



finger, and two for the thumb. The 



first row articulates with the metacarpal bones and the second 

 row of phalanges ; the second row, with the first and third ; and 

 the third, with the second row. 



