226 



RADIAL AND ULNAR ARTERIES. 



opposite vessel, the anterior inosculates with 

 the termination of the anterior interosseous 

 and with small branches sent upwards from 

 the superficial and deep palmar arches: while 

 the arch formed by the posterior joins the 

 posterior interosseous, and the dorsal branch 

 of the anterior interosseous ; and gives off a 

 small branch which occupies each of the two 

 ulnar metacarpal spaces on the back of the 

 hand. 



The communicans ulnce is a branch of large 

 size, which passes away from the posterior 

 surface of the ulnar vessel at about the lower 

 border of the annular ligament, and disappears 

 by sinking between the abductor and opponens 

 minimi digiti, to join, deeply in the palm, with 

 the ulnar extremity of the palmaris profunda 

 or palmar arch of the radial, to which it 

 usually approximates in size. It gives small 

 branches to the muscles while passing between 

 them. 



In the palm of the hand, the digital arteries 

 are the only branches of the vessel which 

 attain any size : there are four of these, the 

 first supplying the ulnar side of the little 

 finger, and the remaining three corresponding 

 each to the opposed sides of two fingers : the 

 most external being between the middle one 

 and the index. They occupy a situation super- 

 ficial to the nerves and tendons, and continue 

 forwards, each as a single branch, until they 

 reach to the clefts of the fingers ; lying in in- 

 tervals between the commencing sheaths of 

 the tendons, and limited in front by the trans- 

 verse ligament of the fingers, and behind by the 

 strong ligament on the heads of the metacar- 

 pal bones. In this space lies also the similar 

 digital branch of the median nerve, but beneath 

 the artery, and at its inferior termination, 

 each bifurcates into branches for the neigh- 

 bouring side of the fingers which bound the 

 cleft. Here the vessels are crossed by the 

 nerves, and in the remainder of their length, 

 are situated along the border of the finger, to 

 its termination, the nerve being anterior. At 

 the extremity of the finger, the branch of each 

 side gives off a twig to the under surface of 

 the nail, and the remainder immediately uniting 

 in an arch with the similar branch of the op- 

 posite side, breaks up into a network, whose 

 meshes thus form a highly vascular subtra- 

 tum to the sensitive papillary surface which 

 especially occupies this part. In its course 

 along the finger, beside many smaller branches, 

 each digital artery gives off a transverse branch 

 lust above the several phalangeal articulations ; 

 which, by joining with its fellow, forms an 

 arch whence proceed the smaller vessels to the 

 joint. 



Varieties of the radial and uJnar arteries. 

 The size of these vessels, together with the 

 comparative exposure to mechanical injury 

 which their situation involves, renders an 

 exact knowledge of their distribution abso- 

 lutely essential to the surgery of the upper 

 extremity ; and the same causes also require 

 that the more important varieties, which con- 

 stitute so large a per centage of their actual 

 numbers, should at least experience some 



consideration. In sketching out a few of these 

 it is impossible to avoid acknowledging great 

 obligations to Mr. Quain's recent work, " The 

 Anatomy of the Arteries," in which the number 

 of subjects, which serve as the groundwork of 

 the estimates, the evident care with which 

 they have been examined, and the beauty of 

 the illustrations, leave little to be wished for. 



Varieties of origin. Rarely does either of 

 the two vessels arise from the brachial at a 

 point lower than the ordinary situation op- 

 posite the coronoid process of the ulna : a 

 higher division of this artery, or as it is called, 

 a " high origin" of one of these its branches, 

 is, on the contrary, by no means an uncommon 

 occurrence, It is worthy of notice, that in 

 the majority of these cases, there is no lateral 

 correspondence of the variety, in the op- 

 posite limb the distribution is the usual one. 



The most frequent of the two is the high 

 origin of the radial, which may come off from 

 the axillary, or from the brachial artery in any 

 part of its course. In this case, the remaining 

 trunk, although directly continuous with the 

 ulnar artery, and lacking the usual means 

 of distinction from it, bears yet the name of 

 brachial, since it generally possesses the ordi- 

 nary relations and distribution of the latter 

 vessel. Under these circumstances, the radial 

 passes down the arm from the place where it 

 is given off, generally lying rather close to the 

 brachial, and on its outer side, until it reaches 

 the forearm ; subsequently it preserves its usual 

 arrangement and termination. But though, 

 for the most part, its course is thus only 

 altered by the possession of an additional por- 

 tion in the upper arm, this irregularity is some- 

 times associated with another which concerns 

 its course, viz., a position of the artery super- 

 ficial to the fascia ; and here it would often 

 have a close juxtaposition to the^median basilic 

 vein at the bend of the elbow, which careless- 

 ness in venaesection might render dangerous 

 or even fatal. A similar deviation may obtain 

 in the remainder of its course, placing it super- 

 ficially to the supinator radii longus, instead 

 of beneath its overlapping inner border; or 

 causing it to cross over the extensor tendons 

 at the wrist instead of under them. The 

 latter variety is frequently associated with 

 another alteration in the course of the vessel, 

 which, after giving off the superficialis volae 

 at a point much higher than usual, immedi- 

 ately turns round the outer border of the 

 forearm, so as to leave this small branch 

 alone occupying its ordinary position at the 

 wrist. Other deviations are comparatively 

 rare: thus occasionally the vessel enters the 

 palm in the second instead of the first inter- 

 osseous space. 



Variations in its distribution appear chiefly 

 dependent on its relative size. If smaller than 

 usual, a kind of enlarged communicans ulnae 

 reinforces its deep palmar arch, or gives off its 

 radialis indicis and magna pollicis branches: 

 or the compensative stream may arrive by 

 another channel, viz., a dilated anterior inter- 

 osseous to join the artery as it turns round 

 the wrist; or by a large posterior branch of 



