SUPERFICIAL PALMAR ARCH. 393 



Branches. The anterior and posterior ulnar recurrent branches frequently arise 



by a common trunk. One or both have been seen to arise from the brachial artery. 



The anterior and posterior interosseous arteries are occasionally given separately 

 from the ulnar. The common interosseous trunk has been found to arise above its 

 ordinary situation, taking origin from the brachial, and even (but more rarely) from 

 the axillary artery. The anterior interosseous presents some striking varieties of 

 excess in its branches, usually connected with a deficiency in the radial or ulnar 

 arteries : the most important of these is enlargement of the median branch. 



Median artery. The branch accompanying the median nerve is sometimes much 

 enlarged, and in such cases may be regarded as a reinforcing vessel. It is generally 

 a branch of the anterior interosseous, but sometimes of the ulnar ; and more rarely 

 a median branch has been met with descending from the brachial artery. Accom- 

 panying the median nerve beneath the annular ligament into the palm of the hand, 

 the median artery ends most frequently by joining the superficial palmar arch, some- 

 times by forming digital branches, in other cases by joining digital branches given 

 from other sources. 



SUPERFICIAL PALMAR ARCH. 



The superficial palmar arch or artery (arcus superficialis volse, Ha Her) is 

 the continuation of the ulnar artery into the hand. Changing its course near 

 the lower border of the annular ligament, this artery turns obliquely out- 

 wards across the palm of the hand towards the middle of the muscles of the 

 thumb, where it terminates by inosculating with a small branch of the 

 radial artery the superficial volar, generally passing through among the 

 muscles of the thumb. In its course across the hand, the palmar artery 

 describes a curve, having its convexity directed towards the fingers, and 

 extending downwards somewhat lower than a line on a level with the pha- 

 langeal articulation of the thumb. 



The superficial palmar artery rests at its commencement on the annular 

 ligament of the wrist, and slightly on the short muscles of the little finger ; 

 then on the tendons of the superficial flexor of the fingers, and the divisions 

 of the median and ulnar nerves, the latter nerve accompanying the vessel 

 for a short distance. It is covered towards the ulnar border of the hand 

 by the palinaris brevis, and afterwards by the palmar fascia and the 

 integument. 



BRANCHES. The branches given off by the superficial palmar arch, which 

 are generally numerous, are as follow. 



(a) The deep or communicating branch arises from the ulnar artery at the 

 commencement of the palmar arch a little beyond the pisiform bone, sinks 

 deeply between the flexor brevis and the abductor of the little finger, and 

 inosculates with the palmar termination of the radial artery, thereby com- 

 pleting the deep palmar arch. 



(6) Small branches, some following a retrograde course towards the annular 

 ligament, are given off to the parts in the palm of the hand from the upper 

 or concave side of the palmar arch. 



(c) The digital branches, usually four in number, proceed downwards 

 from the convexity of the palmar arch to supply both sides of the three 

 inner fingers, and the ulnar side of the fore finger. The first digital branch 

 inclines inwards to the ulnar border of the hand, and, after giving minute 

 offsets to the muscles of the little finger, runs along the inner margin of its 

 phalanges. The second runs along the fourth metacarpal space, and at the 

 root of the fingers divides into two branches, which proceed along the con- 

 tiguous borders of the ring finger and little finger. The third is similarly 

 distributed to the ring finger and middle finger ; and the fourth to the 



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