FRONT OF THE ARM 73 



cords of the brachial plexus, with the exception of the axillary 

 (circumflex), will be found for some part of their course in 

 this region. The radial nerve (musculo-spiral), it is true, 

 almost at once proceeds to the back of the limb, but it 

 again comes to the front, and may be found in the lower part 

 of the lateral side of the arm, by separating the origins of the 

 brachioradialis and extensor carpi radialis longus from the 

 brachialis, and dissecting deeply in the interval between them. 



Dissection. In carrying out this somewhat extensive dissection, the 

 main object of the dissector should be to keep the brachial artery as un- 

 disturbed as possible until he has satisfied himself as to its relations. He 

 is therefore, in the first instance, advised to clean only those parts of the 

 muscles which are in immediate relationship to the vessel and its branches. 

 The divided brachial nerves, with the axillary artery and vein, should be 

 arranged in proper order, and then tied to a small piece of wood about i^ 

 inches long (e.g. a piece of a penholder), held transversely. By means of 

 a loop of string this can then be fastened to the coracoid process. By 

 this device the dissection of the arm will be greatly facilitated. The 

 dissection of the entire length of the brachial artery should be carried 

 out at one and the same time, and its termination in the radial and ulnar 

 arteries should be defined. 



Arberia Brachialis (Brachial Artery) is the direct continua- 

 tion of the axillary artery ; it begins, therefore, at the distal 

 border of the teres major, and it passes distally and slightly 

 laterally to the cubital fossa where, at the level of the neck of 

 the radius, it divides into its two terminal branches the radial 

 and the ulnar arteries. In the proximal part of the arm it lies 

 to the medial side of the humerus, but as it approaches the 

 elbow it passes to the front of the humerus. 



This change of position must be borne in mind when 

 pressure is applied to the vessel with the view of controlling 

 the flow of blood through it. In the upper part of the arm 

 the pressure must be directed laterally and backwards, and in 

 the lower part directly backwards. 



Relations. The brachial artery is superficial in the 

 whole of its length, therefore, to expose it, it is only necessary 

 to reflect the skin and the fascia, but it is overlapped, from 

 the lateral side, by the medial margins of the coraco-brachialis 

 and biceps brachii (see Figs. 30, 31). At the bend of the 

 elbow it is crossed superficially by the lacertus fibrosus which 

 intervenes between it and the median basilic vein. 



The basilic vein lies to the medial side of the artery and 

 on a somewhat posterior plane. In the distal part of the 

 arm it is separated from the artery by the fascia brachii ; but 



