598 THE ARTERIES. 



PLAN OF THE RELATIONS OF THE RADIAL ARTERY IN THE FOREARM. 



In front. 



Skin, superficial and deep fasciae. 

 Supinator longus. 



Inner side. / \ Outer side. 



Pronator radii teres. i^FoVearm 7 Supinator longus. 



Flexor carpi radialis. \ I Radial nerve (middle third). 



Behind. 



Tendon of Biceps. 

 Supinator breyis. 

 Flexor sublimis digitorum. 

 Pronator radii teres. 

 Flexor longus pollicis. 

 Pronator quadratus. 

 Radius. 



At the wrist, as it winds round the outer side of the carpus from the styloid 

 process to the first interosseous space, it lies upon the external lateral ligament, 

 and then upon the scaphoid bone and trapezium, being covered by the extensor 

 tendons of the thumb, subcutaneous veins, some filaments of the radial nerve, and 

 the integument. It is accompanied by two veins and a filament of the musculo- 

 cutaneous nerve. 



In the hand it passes from the upper end of the first interosseous space, 

 between the heads of the Abductor indicis or First dorsal interosseous muscle, 

 transversely across the palm, to the base of the metacarpal bone of the little 

 finger, where it inosculates with the communicating branch from the ulnar artery, 

 forming the deep palmar arch. It lies upon the carpal extremities of the metacarpal 

 bones and the Interossei muscles, being covered by the Adductor obliquus pollicis, 

 the flexor tendons of the fingers, the Lumbricales, the Opponens, and Flexor 

 brevis minimi digiti. Alongside of it is the deep branch of the ulnar nerve, but 

 running in the opposite direction ; that is to say, from within outward. 



Peculiarities. The origin of the radial artery, according to Quain, is, in nearly one case 

 in eight, higher than usual ; more frequently arising from the axillary or upper part of the 

 brachial than from the lower part of this vessel. The variations in the position of this vessel 

 in the arm and at the bend of the elbow have been already mentioned. In the forearm it 

 deviates less frequently from its position than the ulnar. It has been found lying over the fascia 

 instead of beneath it. It has also been observed on the surface of the Supinator longus, instead 

 of along its inner border ; and in turning round the wrist it has been seen lying over, instead of 

 beneath, the extensor tendons. 



Surface Marking. The position of the radial artery in the forearm is represented by a 

 line drawn from the outer border of the tendon of the Biceps in the centre of the hollow in front 

 of the elbow-joint with a straight course to the inner side of the fore part of the styloid process 

 of the radius. 



Surgical Anatomy. The radial artery is much exposed to injury in its lower third, and is 

 frequently wounded by the hand being driven through a pane of glass, by the slipping of a 

 knife or chisel held in the other hand, and such-like accidents. The injury is often followed by 

 a traumatic aneurism, for which the old operation of laying open the sac and securing the vessel 

 above and below is required. 



The operation of tying the radial artery is required in cases of wounds either of its trunk 01 

 of some of its branches, or for aneurism ; and it will be observed that the vessel may be exposed 

 in any part of its course through the forearm without the division of any muscular fibres. The 

 operation in the middle or inferior third of the forearm is easily performed, but in the upper 

 third, near the elbow, it is attended with some difficulty, from the greater depth of the vessel 

 and from its being overlapped by the Supinator longus muscle. 



To tie the artery in the upper third an incision three inches in length should be made 

 through the integument, in a line drawn from the centre of the bend of the elbow to the front 

 of the styloid process of the radius, avoiding the branches of the median vein ; the fascia of 

 the arm being divided and the Supinator longus drawn a little outward, the artery will be 

 exposed. The venae comites should be carefully separated from the vessel, and the ligature 

 passed from the radial to the ulnar side. 



In the middle third of the forearm the artery may be exposed by making an incision of 

 similar length on the inner margin of the Supinator longus. In this situation the radial nerve 



