224 



RADIAL AND ULNAR ARTERIES. 



from the more superficial arch of the ulnar 

 vessel. Their distribution to the fingers cor- 

 responds to that of the arteria dorsalis polli- 

 cis. 



The arteria magna sen princeps pollicis is the 

 first branch given off from the radial in the 

 palm, and, as its name intimates, it is usually 

 of considerable size. From the point of its 

 origin it runs downwards beneath the flexor 

 brevis pollicis and tendon of the flexor longus, 

 lying on the metacarpal bone of the thumb, 

 until near the metacarpo-phalangeal joint ; 

 where it divides into two branches, one of 

 which occupies each border of the phalanges, 

 and joins that opposite in the ordinary manner 

 beneath the sentient cushion which forms the 

 extremity of the thumb. 



The arteria radialis indicis also given off 

 beneath the flexor brevis pollicis, runs yet 

 more vertically downwards than the pre- 

 ceding, beneath that muscle and the adductor 

 pollicis, and on the abductor indicis or first 

 dorsal interosseous muscle, to become super- 

 ficial at their lower borders. Here it gives 

 off a tolerably large communicating branch to 

 the superficial palmar arch of the ulnar artery, 

 and from this point it passes along the radial 

 side of the second metacarpal bone and index 

 finger to its extremity, having a distribution 

 in all respects like that of the digital branches 

 of the palmar arch ; its description is deferred 

 to them. 



From the arch itself are given off few 

 branches of any size. Those which proceed 

 downwards, lying on the palmar interossei, 

 are three in number, one for each space, and 

 anteriorly they end by inosculating with the 

 digital branches from the ulnar, like the small 

 twigs already referred to as occupying the 

 same interosseous position on the dorsum of 

 the hand. They have been named " ante- 

 rior interosseous " branches. The remaining 

 branches of the radial are the jiosterior per- 

 forating, three twigs which perforate the supe- 

 rior extremity of the same metacarpal spaces, 

 to anastomose on the back of the hand with 

 the posterior carpal and metacarpal branches. 



The ulnar artery. The remaining terminal 

 branch of the brachial is usually much larger 

 than the preceding, with which it is also 

 contrasted by the more linear direction of its 

 course, and by its situation in the different 

 regions through which it passes ; since it oc- 

 cupies the front of the limb from its com- 

 mencement to its termination, and is placed 

 less superficially in the forearm than in the 

 hand. 



Its relations in the forearm. In this part 

 of its course its direction is nearly straight, 

 but with a slight convexity inwards, and it 

 corresponds to the ulna in its whole length. 

 At first lying on the brachialis anticus, by 

 passing downwards and rather inwards, it 

 next comes into contact with the flexor pro- 

 fundus digitorum which covers the bone ; 

 and it continues to lie on it to near the 

 annular ligament. Superficial to the vessel 

 are the skin and fascia of the forearm, together 

 with the first layer of the muscles which oc- 



cupy this situation, or the flexors which pro- 

 ceed from the inner condyle ; viz., the pronator 

 radii teres, flexor carpi radialis, palmaris lon- 

 gus, and flexor carpi ulnaris, successively. 

 It is overlapped by the outer head and border 

 of the latter muscle during about two-thirds 

 of the forearm, being only uncovered where 

 it becomes tendinous ; in this lower part the 

 artery lies external to this tendon, situated 

 between it and the two inner tendons of the 

 flexor sublimis ; structures which would form 

 a very easy guide to its locality during life. 

 Although thus uncovered, the artery is by no 

 means so superficial as was the case with the 

 radial in the same stage ; having in front of it 

 fasciae of great strength, and being placed in 

 a deep depression, from the coming forward 

 of the tendon of the ulnar flexor to its in- 

 sertion in the pisiform bone. 



The median nerve, which lay to its inner 

 side on the brachialis anticus, crosses the 

 ulnar artery very soon after the origin of the 

 latter, the point of decussation exactly cor- 

 responding to the coronoid origin of the pro- 

 nator radii teres, which slip of muscle lying 

 over the vessel, separates the two structures. 

 The ulnar nerve at its inner side above, where 

 it enters the forearm between the condyle and 

 olecranon, is in close contact with it in the 

 lower half of this region, placed somewhat 

 superficially and to its inner side. The or- 

 dinary venae comites accompany the vessel. 



In the hand. In this latter part of its course 

 the artery passes over the annular ligament of 

 the wrist, internal both to the pisiform bone 

 and the muscles of the hypothenar eminence ; 

 and next, as the superficial palmar arch, it 

 passes transversely through this part of the 

 hand, crossing superficially to the flexor ten- 

 dons and the branches of the median nerve, 

 until it arrives at the point to which we 

 conducted the superficialis volae, and the 

 communicating branch sent upwards from the 

 radialis indicis ; a point nearly at the inner 

 border of the prominent ball of the thumb. 

 Though placed above the tendons and nerves 

 the artery, however, is far from subcutaneous 

 in any part of its progress ; for while on the 

 annular ligament, fibres from the insertion of 

 the flexor carpi ulnaris into the pisiform bone 

 pass outwards over its surface to join that 

 structure external to the vessel lying on it ; 

 a little further downwards, the palmaris brevis, 

 where present, is also directed inwards in 

 front of it ; and during the remainder of its 

 length, the strong palmar fascia effectually 

 shields it from immediate pressure. The ver- 

 tical part of the vessel is accompanied by the 

 ulnar nerve, which maintains the relation it 

 had in the lower part of the forearm, and, 

 interiorly, divides into its digital branches. 

 The arch, like that of the radial artery, pre- 

 viously described, is convex downwards, con- 

 cave upwards; but it is obvious _that its 

 situation is considerably inferior to it, as well 

 as much more superficial. A transverse line - 

 across either the middle of the hand or the 

 centre of the metacarpus would tolerably 

 indicate its position, or one continued across 



