1 10 CUNEIFORME PISIFORME TRAPEZIUM. 



attachment of ligaments ; the other palmar, which is convex, rounded, 

 and of larger size. 



To determine to which hand it belongs, let the bone be held perpendi- 

 cularly, so that the dorsal or flat extremity look upwards, and the convex 

 side backwards (towards the holder). The circular lateral surface will 

 point to the side corresponding with the hand to which the bone belongs. 



Articulations. With five 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 unci- 

 form. This surface is divided into two parts by a ridge when it articu- 

 lates with the unciform as well as with the cuneiform bone. 



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

 be best distinguished by a circular and isolated facet, which articulates 

 with the pisiform bone. It presents for examination three surfaces, 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 round and pointed. 



To distinguish its appropriate hand, let the base be directed backwards 

 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 unci- 

 forme ; by the circular facet, with the pisiforme ; and by the superior angle 

 of the rough surface, with the fibro-cartilage. 



The PISIFORM bone maybe recognised by its small size, and by possess- 

 ing a singular articular facet. If it be examined carefully it will be ob- 

 served to present four sides and two extremities ; one side is articular, 

 the smooth facet approaching nearer to the superior than the inferior ex- 

 tremity. 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 downwards 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 abductor 

 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 somewhat 

 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 radialis, which is surmounted by 

 a prominent tubercle for the attachment of the annular ligament ; the other 

 two borders are rough and form the outer side of the carpus. The grooved 

 border is narrow at one extremity and broad at the other, where it pre- 

 sents the groove and tubercle. 



If the bone be held so that the grooved border look upwards while the 

 ,<[iex fcf this border be directed forwards, and the base with the tubercle 



