84 CUNEIFORMS TRAPEZIUM. 



surface will point to the side corresponding with the hand to which 

 the bone belongs. 



Articulations. With Jive bones, but occasionally with only four ; 

 by its convex surface, with the radius ; by its concave surface, with 

 the os magnum ; by its crescentic lateral facet, with the scaphoid ; 

 and by the circular surface, with the cuneiform bone and with the 

 point of the unciform. This surface is divided into two parts by a 

 ridge when it articulates with the unciform as well as with the cunei- 

 form bone. 



The CUNEIFORM bone, although somewhat wedge-shaped in form, 

 may be best distinguished by a circular and isolated facet, which arti- 

 culates with the pisiform bone. It presents for examination three sur- 

 faces^ a base, and an apex. One surface is very rough and irregular ; 

 the opposite forms a concave articular surface, while the third is partly 

 rough and partly smooth, and presents that circular facet which is 

 characteristic of the bone. The base is an articular surface, and the 

 apex is rough and pointed. 



To distinguish its appropriate hand, let the base be directed back- 

 wards and the pisiform facet upwards ; the concave articular surface 

 will point to the hand to which the bone belongs. 



Articulations. With three bones, and with the triangular fibro- 

 cartilage. By the base, with the semilunare ; by the concave surface, 

 with the unciforme ; by the circular facet, with the pisiforme ; and b}' 

 the superior angle of the rough surface, with the fibre-cartilage. 



The PISIFORM bone may be recognized by its small size, and by 

 possessing a singular articular facet. If it be examined carefully, it 

 will be observed to present four sides and two extremities ; one side 

 is articular, the smooth facet approaching nearer to the superior 

 than the inferior extremity. The side opposite to this is rounded, 

 and the remaining sides are, one slightly concave, the other slightly 

 convex. 



If the bone be held so that the articular facet shall look down- 

 wards, and the extremity which overhangs the articular facet forwards, 

 the concave side will point to the hand to which it belongs. 



Articulations. With the cuneiform bone only. 



Attachments. To two muscles, the flexor carpi ulnaris, and abduc- 

 tor minimi digiti ; and to the anterior annular ligament. 



The TRAPEZIUM (os multangulum majus) is too irregular in form to 

 be compared to any known object ; it may be distinguished by a deep 

 groove, for the tendon of the flexor carpi radialis muscle. It is some- 

 what compressed, and may be divided into two surfaces which are 

 smooth and articular, and three rough borders. One of the articular 

 surfaces is oval, concave in one direction, and convex in the other 

 (saddle-seat shaped); the other is marked into three facets. One of 

 the borders presents the groove for the tendon of the flexor carpi ra- 

 dialis, which is surmounted by a prominent tubercle for the attach- 

 ment of the annular ligament ; the other two borders are rough and 

 form the outer side of the carpus. The grooved border is narrow at 



