44*6 THE ARTERIES OF THE UPPER LIMB. 



As to size, the ulnar artery presents some varieties which are generally accompanied by 

 deviations of an opposite and compensating 1 character in the radial artery ; but as these 

 influence the extent of the distribution of the ulnar artery in the hand, they will be noticed 

 in connection with the varieties of the vessels of that part. 



JB ranches. 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 anterior interosseous artery has been seen of large size, reinforcing- the radial or, 

 more rarely, the ulnar artery by means of a transversely directed branch joining the main 

 trunk at the wrist (enlargement of an anterior carpal artery) ; or its posterior branch has 

 been seen joining the radial on the back of the hand. More frequently it gives off a large 

 median artery. 



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 or axillary artery. Generally accompanying the 

 median nerve beneath the annular ligament, occasionally however passing over the front of 

 the ligament, it enters the palm of the hand and there ends, most frequently by joining the 

 superficial palmar arch, sometimes by forming digital branches, and in other cases by joining 

 digital branches given from other sources (figs. 360, 369). 



SUPERFICIAL PALMAR ARCH (IV). 



The superficial palmar arch is the continuation of the ulnar artery in the hand. 

 As it passes over the anterior annular ligament the ulnar artery gives off its deep 

 branch, and a little below that band it turns outwards across the palni of the hand 

 towards the middle of the muscles of the thumb. In this course the vessel 

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

 downwards somewhat lower than a line on a level with the inetacarpo phalangeal 

 articulation of the thumb. The arch is sometimes completed on the outer 

 side by inosculating with the superficial volar branch of the radial artery, and 

 in many cases it is connected also, by a small branch, with the radialis indicis 

 or princeps pollicis artery at the lower border of the adductor transversus pollicis 

 muscle. 



The superficial palmar arch 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 palmaris brevis, and afterwards 

 by the palmar fascia and the integument. 



BRANCHES. The superficial palmar arch gives off small twigs .to the superficial 

 muscles and integument of the palm, and the following larger branches to the 

 fingers : 



The digital arteries (v), usually four in number, proceed downwards from the 

 convexity of the palmar arch to supply both sides of the inner three fingers, and the 

 ulnar side of the fore finger. The first digital branch (often derived from the deep 

 arch) 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 intermetacarpal space, and at the 

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

 contiguous borders of the ring and little fingers. The third is similarly dis- 

 tributed to the ring and middle fingers ; and the fourth to the middle and index 

 fingers. The thumb and the radial side of the index finger are supplied from the 

 radial artery. 



The digital arteries descend in the intervals between the flexor tendons, resting 

 upon the digital nerves and lumbricales muscles, as far as the clefts of the fingers, 



