452 



THE ARTERIES OF THE UPPER LIMB. 



2. The superior perforating branches, three in number, frequently arise in 

 common with the following branches ; they pass backwards through the , upper 

 extremities of the inner three interosseous spaces to inosculate with the dorsal 

 interosseous arteries. 



3. The palmar interosseous arteries, usually three in number, but very 

 liable to variation, lie in front of the interosseous spaces, supply the muscles there, 

 and inosculate at the clefts of the fingers with the digital branches from the super- 

 ficial arch. There is generally also a communicating branch passing from the inner- 



Fig. 368. DEEP ARTERIES OF THE WRIST AND PALM. 

 (R. Quain.) 



The anterior annular ligament of tlie wrist has been divided ; 

 the lower parts of the common flexors and the long flexor of the 

 thumb have been removed, and portions of these tendons are 

 turned down upon the fingers with parts of the lumbricales mus- 

 cles ; the superficial palmar arch is removed, and the interosseous 

 muscles are exposed : a, ulnar nerve ; b, tendon of flexor carpi 

 ulnaris ; c, tendon of flexor carpi radialis ; d, tendon of extensor 

 ossis metacarpi pollicis ; 1, radial artery ; 1', its lower part giving 

 off the anterior carpal and superficial volar branches, the latter 

 cut short ; 2, ulnar artery ; 3, anterior interosseous artery, passing 

 behind the pronator quadratus ; 4, radial artery, appearing deeply 

 in the palm between the first and second metacarpal bones and 

 passing into the deep palmar arch ; 5, deep branch of the ulnar 

 artery, dipping between the abductor and flexor brevis minimi 

 digiti to join the deep arch, and accompanied by the deep branch 

 of the ulnar nerve ; 6, a digital artery, arising from the first part 

 of the superficial palmar arch ; 7, princeps pollicis, and 8, 

 radialis indicis arteries ; 9, 9, 9, interosseous branches of the 

 deep palmar arch, proceeding down on the interosseous muscles to 

 join the palmar digital arteries from the superficial arch. 



most interosseous artery, or from the deep arch 

 itself, to the digital artery of the inner side of the 

 little finger. 



It is by an enlargement of these small vessels 

 that the deep palmar arch sometimes supplies the 

 corresponding digital arteries when those derived from 

 the superficial arch are small or absent. 



Varieties of the arteries of the hand. The arteries of the hand frequently vary from 

 their usual mode of distribution. 



O) By far the larger number of deviations consist of a deficiency in either the radial or 

 ulnar system of arteries, accompanied by a corresponding increase in the other ; and it may 

 be observed that the defect is much more commonly on the part of the superficial, and the 

 increase on the part of the deep set. 



(&) In the second and smaller class of variations a deficiency in one or other of the two 

 systems is supplied, either by the enlargement of branches which descend in front of the 

 limb, as the superficial volar (from the radial), or the median artery (from the anterior inter- 

 osseous, as shown in fig. 369), or by the enlargement of an interosseous branch (from the 

 radial) on the back of the hand. 



In illustration of these general remarks, the following mode of arrangement of the vessels 

 may be mentioned : 



In the greater number of cases the superficial palmar arch is diminished, and gives off 

 fewer digital branches than usual. Generally only one branch is wanting, viz., that which 

 supplies the adjacent sides of the fore and middle fingers ; but sometimes two or three 

 branches are absent, or even all four, as when the ulnar artery, after giving branches to the 

 short muscles of the little finger, ends in the deep palmar arch. In the last-mentioned case, 

 which is rare, it is obvious that the superficial arch is altogether wanting. 



These various deficiencies in the superficial palmar arch and its branches are usually com- 

 pensated by an enlargement of the deep arch, the palmar interosseous branches of which, 

 being increased in size, divide at the clefts of the fingers, and form such collateral digital 

 branches as are not derived from the usual source. But a defective superficial arch may, as 



