This section is from the book "Anatomy Of The Arteries Of The Human Body", by John Hatch Power. Also available from Amazon: Anatomy of the Arteries of the Human Body, with the Descriptive Anatomy of the Heart.
The origin of either vessel in the arm or axilla has been already noticed. Sometimes the ulnar artery arises regularly at the bend of the elbow, yet afterwards it descends on the cutaneous surface of the muscles arising from the internal condyle, and accompanies the basilic vein. The radial artery may also, though regular in its origin, run superficial to the fascia. These latter irregularities are very rare. Dr. Green, when speaking of the irregular origin of the ulnar high up in the arm, observes, " it pursues its course along the fore-arm, immediately under the fascia."*
* Green on the " Varieties in the Arterial System," p. 17. Surgical Anatomy of the Arteries, p. 192.
He remarks also, concerning the irregular origin of the radial, that " in some rare instances the vessel pierces the brachial aponeurosis, and becomes quite superficial; but more usually it is covered by the tendinous expansion." He states that he has seen but one instance of the irregular radial lying superficial to the fascia: Tiedemann makes the same remark.
Dr. Barclay describes a case in which both radial and ulnar were superficial. Dr. Green saw a case in which a transverse branch joined the radial and ulnar at the lower third of the fore-arm. Sometimes the radial artery gives off the superficialis volae high up in the fore-arm: this is more likely to occur in case of a high bifurcation of the brachial. If the superficialis volae arise high up, the continued trunk of the radial may either descend along with it and on a deeper plane, or may turn round the radius near the lower third of the forearm, and descend in this region to the hand. Dr. Green saw two cases of this description.
In addition to the above, we may quote the following remarkable variety, observed by Mr. Bennett Lucas at the North London School of Medicine :
" A female, aged seventy, exhibited in the distribution of her arteries the most uniform irregularity. Those of the upper extremities I have alone preserved, as they arc highly interesting in a practical point of view. The brachial artery of the right side bifurcated as usual at the bend of the elbow into radial and ulnar arteries; but the radial was infinitely the larger. The ulnar artery, after running its usual course for about two inches, suddenly sent off a leash of branches ; viz., a large recurrent, several fair-sized muscular, a huge interosseal, which ran down to terminate in the deep palmar arch, and a middle-sized ' continued trunk,' which lost itself in the superficial palmar arch, as it scarcely could be said to assist in its formation. The great radial trunk went its way, detaching few and insignificant twigs, and a quarter of an inch above the wrist-joint sent off a superficialis volae, more as a matter of form than any thing else, for it soon expended itself in the muscles of the thumb. The undiminished trunk of the radial now turned round the outer edge of the carpus, and, at the angle formed by the metacarpal bones of the thumb and index finger, sent off two branches, the larger of which (the other being spent in the adductor pollicis and abductor indicis muscles) coursed along the inner edge of the metacarpal bone of the thumb, furnishing the princeps pollicis, radialis indicis, and a retrograde branch, to form, with the nearly exhausted ulnar artery, the superficial palmar arch. From this arch proceeded four branches, the smaller of which went to the inner edge of the little finger, the next bifurcated to supply the opposed sides of the little and ring fingers, the third bifurcated to supply the opposed sides of the ring and middle fingers, but the fourth, a pitiable vessel, ran to the head of the third metacarpal bone, and there joined a large digital trunk derived from the deep palmar arch. The continued trunk of this radial artery, at length sensibly diminished, took its usual course to form the deep palmar arch. At the proximal end of the metacarpal bone of the index finger, the large digital artery, already alluded to (merely acknowledging the receipt of the fourth superficial palmar artery), bifurcated to supply the opposed sides of the middle and index fingers. After forming the deep palmar arch, which sent off the usual arteries to the smaller palmar muscles, the radial trunk ran under the cover of the muscular mass of the little finger, sending numerous branches therein, 33* and then playfully turned upwards under the annular ligament, and united with the large interosseal artery from the ulnar.
* Green on the " Varieties in the Arterial System," p. 21. Op. Cit., p. 19. Tied. Tab. Art., p. 169.
"In this very uncommon, if not unique, distribution of arteries, we find the radial (a huge trunk) taking its usual course, and supplying the palm of the hand and all the fingers. Intent upon this purpose, it sends off but few, and these small, muscular branches, and a superficialis volae of no account; and, merely condescending to make an intimacy with the ulnar and interosseal arteries, it takes upon itself, not alone to form the superficial palmar arch, but to form it much less in extent than the deep palmar arch,the arch which it forms in the natural distribution, and which is in such case much the smaller.
"On the left side of this subject the brachial artery divided as usual; but here the ulnar artery was very large and the radial artery very small. The radial, immediately after its origin, sent off the superficialis volae, which vessel, though nearly the length of the fore-arm, was very delicate, and, after detaching several small muscular branches, lost itself in the muscles of the thumb, without participating in the formation of the palmar arch. In its course, it occupied the position of the radial artery. The radial trunk itself ran very superficially, and, at the junction of the middle and inferior thirds of the fore-arm, turned round the edge of the radius to the space between the metacarpal bones of the thumb and index finger, where it sent off the palmaris profunda to form the deep palmar arch in the usual manner, the radialis indicis and the princeps pollicis, and, in addition, a second palmaris profunda, which formed, by joining the trunk of the ulnar artery, a second deep palmar arch.
" The large ulnar sent off its recurrent branches, a posterior interosseal artery, two anterior interosseal arteries, and a long muscular artery. At the wrist it sent off its usual communicating artery, and in the palm of the hand, having received the second deep palmar branch of the radial, it supplied, as usual, three fingers and a half, without, however, forming any superficial palmar arch.
" The practical inferences to be deduced from these unusual distributions are plain, and of some importance. Had this individual been the subject of illness during her life, a very erroneous estimate of its intensity must have been indicated by the pulse; and did the practitioner depend chiefly on its condition, his practice would have been guided by the wrist he felt it at. Here, if the right pulse be felt, from the size of the radial, depletory measures would in all likelihood have been pursued ; and were it the left, an opposite mode of treatment may have been adopted; and if both wrists were examined, they would, at the least, have given cause for deliberation in the case.
" In addition to the varieties of arteries always being, when they exist, a source of difficulty when a vessel is required to be secured, this individual, did she require to have her left fore-arm amputated, would have presented to the surgeon no less than seven considerable arteries for the ligature".