THE RADIAL ARTERY. 413 



fi-om Ti'liich proceed numerous small offsets to supply the matrix of the 

 nail and all the structures at the tip of the finger. 



[The varieties observed in the branches of the superficial pahnar arch will be 

 noticed after the description of the deep arteries of the hand.] 



EADIAL ARTERY. 



The radial artery appears by its direction to be the continuation of 

 the brachial, although it does not equal the ulnar in size. It extends 

 along the front of the fore-arm as far as the lower end of the radius, 

 below which it turns round the outer border of the wrist, and descends 

 to the back of the space between the metacarpal bones of the thumb 

 and fore finger : there it passes forwards into the palm of the hand, and 

 crosses towards the inner side, so as to form the deep palmar arch. In 

 consequence of the changes in its course, the dii'ection and connections 

 of the radial artery may be separately described in the forearm, on the 

 wrist, and in the hand. 



In the forearm the radial artery, commencing at the point of bifur- 

 cation of the brachial opposite the neck of the radius, descends at 

 first somewhat obliquely outwards in a line with the brachial artery, 

 and then nearly vertically along the outer part of the front of the fore- 

 arm to the styloid process of the radius. Its course may be indicated 

 by a line drawn from the middle of the bend of the elbow to the narrow 

 interval between the trapezium bone and the tendons of the extensors 

 of the thumb, which can be readily felt on the outer border of the 

 wrist. 



The radial artery is nearer to the surface than the ulnar, and is 

 covered only by the common integument and fascia, except where it is 

 overlapped by the fleshy part of the supinator longus, which must be 

 drawn aside in order to bring the vessel into view. At first it is in 

 contact with the tendon of the biceps, and is supported by the fatty 

 tissue contained in the hollow in the front of the elbow, which sepa- 

 rates it from the short supinator muscle. It then rests in succession 

 on the insertion of the pronator teres, the thin radial origin of the 

 flexor sublimis, tlie flexor pollicis longus, the pronator quadratus, and 

 the lower end of the radius. It is at this last point that the pulse is 

 usually felt during life. To the inner side of this vessel lie the pro- 

 nator teres in the upper part of its course, and the flexor carpi radial is 

 in the remainder ; and on the outer side, in its whole course along the 

 fore-arm, is the supinator longus muscle. 



Relation to Veins.— T\\q artery is accompanied by venre comites, which 

 liave the usual arrangement of those veins. 



Relation to Nerves. — The radial branch of the musculo-spiral nerve is 

 placed on the outer side of the artery in the middle third of its course. 

 At the elbow that nerve is separated from the artery by a considerable 

 interval ; and towards the lower end of the fore-arm it turns back- 

 Avards beneath the tendon of the supinator longus, to reach the dorsal 

 aspect of the limb, and thus loses all connection with the artery. Some 

 filaments of the external cutaneous nerve pierce the fascia to reach the 

 lower part of the artery, which they accompany to tlie back of the 

 carpus. 



At the wrist the radial artery turns outwards between th.e styloid 

 process of the radius and the carpus, beneath the tendons of the 



