Anatomy of Skeleton 



line of the axis of movement of the second row on the first the shape of the articu- 

 lating surfaces is appropriately changed, and at the same level on the outer side 

 a similar form of curve is formed between the scaphoid and the trapezoid and 

 trapezium. 



All the bones of the carpus, with the exception of the pisiform, are affected by 

 the anterior concavity of the whole structure, and this form is maintained by strong 

 ligaments that are divisible into dorsal and palmar : the latter are the stronger set, 

 as more strain is thrown on them in many of the functions of the hand, but it must not 

 be forgotten that the anterior annular ligament, passing between the extremities of the 

 curve, is the most effective factor in holding up the concavity of the carpus. 



The bones of each row are joined together by interosseous ligaments, so that non-articular 

 rough areas can be found on their sides, bordering on their articular surfaces, for these bands. 

 The ligaments of the first row cut off the cavity of the radio-carpal from that of the mid-carpal 



joint, while this is again separated 

 in part by the interosseous ligaments 

 of the second row from that of the 

 carpo-metacarpal system. 



i. *y In addition to these, the bones 



of the lower row are joined by an- 

 terior and posterior transverse inter- 

 carpal ligaments, which also extend 

 on to the metacarpals. The trans- 

 verse fibres that cover the first row 

 are mainly connected with the radio- 

 carpal fibres of the wrist-joint. 



The transverse fibres are partly 

 covered in front by the radiating 

 fibres of the ligaments that help to 

 connect the two rows with one 

 another. These run from the os 

 magnum to the neighbouring bones, 

 the scaphoid, cuneiform, unciform, 

 trapezoid, and the four inner meta- 

 'carpals : some of these fibres also 

 reach the radius, and a band goes 

 to the base of the styloid process of 

 the ulna, thus not interfering with 



FIG. 84. I, A scheme of a section showing how the flexor 

 sheath occupies the carpal concavity, how the front wall 

 of the sheath is thickened as the annular ligament, and 

 how the carpal bones projecting on each side beyond the 

 sheath are utilised and covered by thenar and hypo- 

 thenar muscles. T. trapezium ; U. unciform. 2, Seen 

 from the front, showing the flexor sheath lying on the 

 carpus and metacarpus. The thick lines mark the side 

 limits and attachments of the annular ligament : the 

 marginal parts of the carpus project beyond these. 

 The muscles arising from the projecting parts run down to 

 the digits along the sides of the sheath, so that there are 

 two side compartments and a central one for tendons 

 and lumbricals. The superficial side muscles overlap the 

 sheath at their origins, i.e., they arise from the annular 

 ligament. 



rotation of the radius and hand 



round that bone. These radiating fibres are continuous in part with the fibres of the anterior 

 capsule of the wrist. The two rows of bones are also connected at their margins by internal and 

 external lateral ligaments which are continuous with the fibres of the lateral ligaments of the 

 wrist, and by ligamentous or tendinous bands connecting the pisiform with the hook of the unci- 

 form and with the bases of the inner two or three metacarpals. 



~ On the back of the carpus the first row is covered by radio-carpal bands passing downwards 

 and inwards, and with these some fibres between scaphoid and cuneiform : some ligamentous slips 

 from these pass to the bones of the lower row. In addition are vertical fibres between the ulna and 

 cuneiform, and cuneiform and unciform, on the inner side, and from radius to scaphoid and scaphoid 

 to trapezium on the outer side. 



If we now analyse the carpal concavity, we see that the projection forwards on the 

 radial side is due to the position and shape of the bones themselves, so that the trape- 

 zium and outer part of the scaphoid are turned forward, carrying the thumb in front 

 of the rest of the metacarpus. On the inner side the cuneiform and unciform lie more 

 in line, and the projection is brought about by the pisiform placed in front of the cunei- 

 form and by a hook-like process whence its name projecting forward from the 

 unciform. But the carpus between these margins is concave forward, so that we find 



