102 TEE CAT. [CHAP. IV. 



perform the motions of pronation and supination without danger of 

 dislocation. 



When the fore-leg and paw hang down, the sole of the fore- 

 foot — or palmar surface — ^being directed forwards, the position is 

 that of supination, and the bones of the fore-arm are situate side 

 by side. 



When the fore-leg and paws are placed as in the act of walking, 

 the position is that of pronation, and the radius crosses over the 

 ulna. 



A ligament has already been mentioned which connects the 

 shafts of the radius and ulna. This is the interosseous Hgamcnt or 

 membrane. It is a thin sheet of fibres which proceed obliquely 

 downwards and inwards from the ulnar margin of the radius to the 

 radial margin of the ulna. 



The two rows of carpal bones are connected together by dorsal, 

 palmar, and lateral ligaments, so that they form an arch concave 

 towards the palm. Synovial membrane is interposed between the 

 proximal and the distal series of carpals. 



The anterior annular ligament is a strong fibrous band from the 

 scapho-lunare and trapezium to the pisiforme, thus forming, with 

 the bones, a ring through which the tendons for bending the fingers 

 may pass down to the digits. 



Th-Q piosterior annular ligament proceeds from the outer margin of 

 the lower part of the radius to the inner part of the cuneiform and 

 pisiform, forming a sheath through which the tendons for extending 

 the fingers pass down to the digits. 



The proximal ends of the four ulnar metacarpals arc joined to 

 the carpus by dorsal, palmar, and interosseous ligaments. The first 

 metacarpal is united to the trapezium by a caj)sular ligament. 

 Synovial membranes are interposed between the successive phalanges, 

 and between the phalanges and the metacarpals. The distal ends 

 of the metacarpals are united to the proximal phalanges by lateral 

 and palmar ligaments. 



The last phalanx of each digit is bound to the last but one by a 

 very elastic ligament (Fig. 63), which passes from the dorsal surface 

 of the hinder part of the distal phalanx to the distal part of the 

 middle phalanx, and by its action keeps the former phalanx rolled 

 back upon the latter. It is put on the stretch, and the claw is 

 drawn downwards by a flexor tendon (to be described with the 

 muscles), which is held in place by a ligamentous loop attached to 

 the palmar surface of the proximal phalanx. 



An intcrmctaearjjal ligament passes from the palmar as})eet of the 

 distal end of the metacarpal of the poUcx to the distal palmar 

 surface of the metacarpal of the index. 



§ 10. A GENiniAL VIEW of the pectoral appendicular skeleton, 

 shows us that it forms an incomplete bony girdle, which is attached 

 to the axial skeleton on its dorsal aspect by soft parts only ; but it 

 is connected with the ventral parts of the appendicular skeleton 

 by the clavicles and by ligaments. The elbow-joint is so bent as to 



