THE ULNAR ARTERY. 



445 



to form the posterior carpal arch. From this arch are derived the second and third 

 dorsal interosseous arteries, which descend over the spaces between the third and 

 fourth and the fourth and fifth metacarpal bones, and are reinforced at the upper 



Fig. 364. HIGH ORIGIN AND SUPERFICIAL COURSE OF THE 



ULNAR ARTERY. 



a, biceps muscle covered by the deep fascia ; b, b, fascia of the y 

 forearm, which has been opened in a considerable extent to show the I 

 radial artery subjacent to it ; c, median nerve ; d, ulnar nerve ; 1, on 

 the biceps muscle, points to the brachial artery after having given off 

 the ulnar artery higher up, and dividing at 1', into the radial artery 

 and a deep vessel corresponding to the interosseous and a part of the 

 normal uluar ; 2, on the supinator longus muscle, points to the radial 

 artery ; 3, 3, artery which is given off by the brachial in the arm, and 

 which, descending upon the fascia, takes the place of the ulnar at the 

 wrist ; 3', the same continued into the superficial palmar arch ; 4, 

 superficial volar branch of the radial ; 5, 5, digital branches. 



ends of those spaces by the junction of the superior 

 perforating branches of the deep palmar arch. 



5. The anterior ulnar carpal branch is a very 

 small artery, which runs on the anterior surface of the 

 carpus beneath the flexor profundus, anastomoses with 

 a similar offset from the radial artery, and supplies the 

 carpal bones and articulations. 



Varieties. Or iy in. In the whole number of cases observed 

 by R. Quain, the ulnar artery was found to deviate from its 

 usual mode of origin nearly in the proportion of one in thirteen. 

 The brachial artery was, more frequently than the axillary, the 

 source from which it sprang ; and the lower part of the brachial 

 more frequently than the upper. In one case of high origin of 

 the ulnar artery, the vessel was connected with the brachial 

 opposite the elbow-joint by means of a transverse branch. 1 

 See, on this subject, the remarks on the varieties of the axillary 

 and brachial arteries. 



Course. The position of the ulnar artery in the forearm is 

 more frequently altered than that of the radial. 



In cases of high origin it almost invariably descends over 

 the muscles arising from the inner condyle of the humerus. 

 only one exception to this rule having been met with by 

 R. Quain. In one instance the ulnar artery taking this course 

 divided just below the elbow into a superficial and deep 

 branch. 1 



Most commonly in such cases it is covered by the fascia of 

 the forearm ; but instances also occur in which the artery rests 

 on the fascia, and either continues in that position or again 

 sinks beneath the fascia lower down, while the vessel thus dis- 

 posed is distributed below after the manner of the normal 

 ulnar artery. The vessel from which the high ulnar separates 

 is afterwards divided into the radial artery and the interosseous ; 

 it appears therefore probable that the abnormal arrangement 

 results from early obstruction of the ulnar artery below the 

 origin of the interosseous, and the development of a superficial 



vas aberrans, which unites the portion of vessel below the obstruction with the axillary or 

 brachial trunk. The interosseous artery in such cases of abnormality thus comprises not 

 only the ordinary interosseous branch, but likewise the portion of ulnar artery above the 

 obstruction ; and, in accordance with this view, we find that the recurrent branches are 

 derived from it. 



The ulnar artery has been seen occasionally taking a superficial course when arising in the 

 usual situation, and in these cases also the recurrent and interosseous arteries are given off by 

 the radial trunk. 



1 W. Gruber, Archiv fur Anatomic, 1871. 



