100 



DISSECTION OF THE UPPER LIMB. 



extension. 



Lower ends 

 of radius 

 and ulna 

 joined by 



capsule, 



triangiilar 

 tibro-carti- 

 lage: 



attach- 

 ments, 



and rela- 

 tions. 



Synovial 

 membrane. 



Bones are 

 .joined into 

 two rows. 



Dissection 

 of carpal 



and nieta- 



carpal 



joints. 



How first 

 row is 

 united 



projects behind, stretching the posterior ligament. In extension 

 the hand is carried backwards, and the row of carpal bones moves 

 in the opposite direction, viz., from behind forwards, so as to cause 

 the anterior ligament to be tightened. The backward movement 

 is not so free as the forward. 



LOWER RADIO-TJLNAR ARTICULATION. In this articulation the 

 head of the ulna is received into the sigmoid cavity of the radius ; 

 an arrangement just the opposite to that between the upper ends 

 of the bones. 



The chief bond of union between the bones is a strong fibro- 

 cartilage ; but a capsule, consisting of scattered fibres, surrounds 

 loosely the end of the ulna. 



The triangular fibro-cartilage (fig. 42, c) is placed transversely 

 below the end of the ulna, and is thickest at its margins and apex. 

 By its base the cartilage is fixed to the ridge which separates the 

 carpal from the ulnar articulating surface of the radius ; and by its 



apex to the styloid process of the 

 ulna, and the depression at the root 

 of that projection. Its margins are 

 united with the contiguous anterior 

 and posterior ligaments of the wrist- 

 joint ; and its surfaces enter into the 

 radio-carpal and the lower radio-ulnar 

 articulations. It serves to unite the 

 radius and ulna, and to form part 

 of the socket for the carpal bones. 

 Occasionally it is perforated by ai 

 aperture. 



The synovial membrane is very 

 loose, and ascends between the radius 

 and the ulna : it is separated from 

 that of the wrist - joint by the 

 triangular fibro-cartilage. 

 The motion in this articulation is referred to with the movements 

 of the radius (p. 98). 



UNION OF THE CARPAL BONES. The several bones of the carpus 

 (except the pisiform) are united into two rows by small dorsal, 

 palmar, and interosseous bands ; and the two rows are connected 

 together by wide separate ligaments. 



Dissection. The articulations of the carpal bones with each othei 

 will be prepared by taking away all the tendons from the hand, and 

 cleaning carefully the connecting ligamentous bands. Two distinct 

 ligaments from the pisiform bone to the unciform (pisi-unciform') 

 and to the fifth metacarpal (pisi-metacarpal} are to be defined in the 

 palm (p. 62). 



At the same time the ligamentous bands uniting the meta- 

 carpal with the carpal bones, and with one another should be 

 dissected. 



BONES OF THE FIRST ROW (fig. 43). The semilunar bone is 

 united to the scaphoid and pyramidal by dorsal (t) and palmar 



FIG. 42. LOWER ENDS OF THE 

 FOREARM BONES WITH THE 

 UNITING FIBRO-CARTILAGE. 



a^ Radius. b. Ulna. 



c. Triangular fibro-cartilage. 



