BRANCHES OF THE RADIAL ARTERY. 397 



the flexor carpi radialis in the remainder ; and on the outer side, in its whole 

 course along the forearm, is the supinator longus muscle. 



Relation to Veins. The artery is accompanied by venae comites, which 

 have 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 forearm it turns backwards 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 the back of the carpus. 



At the wrist the radial artery turns outwards between the styloid process 

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

 metacarpal bone and first phalanx of the thumb, and upon the external 

 lateral ligament of the wrist-joint, to reach the back of the carpus. It then 

 runs downwards for a short distance, is crossed by the tendon of the 

 extensor of the second phalanx of the thumb, and, reaching the upper end of 

 the space between the first and second metacarpal bones, turns forwards 

 iuto the palm of the hand, by passing between the heads of the first dorsal 

 interosseous muscle. 



As it turns round below the end of the radius the artery is deep-seated, 

 but afterwards conies nearer to the surface. It is accompanied by two 

 veins and by some filaments of the external cutaneous nerve, and is crossed 

 by subcutaneous veins and by filaments of the radial nerve. 



BLANCHES. The branches of the radial artery may be arranged according 

 as they are given off in the forearm, on the wrist, and in the hand. 



A. The branches which arise from the radial in the forearm are the 

 radial recurrent, the muscular branches, the anterior carpal, and the 

 superficial volar. 



(a) The radial recurrent artery, which varies much in size, arches upwards 

 from the radial soon after its origin, running between the branches of the 

 musculo-spiral nerve. It first lies on the supinator brevis, and then on the 

 brachialis anticus, being covered by the supinator longus. In front of the 

 outer condyle, and in the internal between the two last muscles, it anasto- 

 moses with the terminal branches of the superior profuuda. 



From the lower or convex side of this artery are given off several branches ; one, 

 of considerable size, to the supinator and extensor muscles, and some beneath the 

 latter to anastomose with the posterior interosseous branches. It also supplies the 

 supinator brevis and brachialis anticus in part. 



(6) The anterior radial carpal is a small branch which arises from the 

 radial artery, near the lower border of the pronator quadratus, and runs 

 inwards in front of the radius. It anastomoses with the anterior ulnar 

 carpal artery, so as to form an arch above and in front of the radio-carpal 

 articulation, from which branches descend to supply the joints at the 

 wrist. 



(c) The superficial volar (ramus superficial volae), arising from the radial 

 artery, near the place where it leaves the front of the forearm, passes on- 

 wards into the hand. In size it is variable; in most instances it is very 

 small, and ends in the muscles of the thumb ; but in others it attains con- 

 siderable size, and crossing those muscles at their origins, terminates, as is 

 usually described, by inosculating with the radial extremity of the super- 

 ficial palmar arch, which it -thus completes. 



