BRACIIIAL ARTERY. 



1011 



the vessel be behind the muscular fibres, and will guide him to the place at 

 which they ought to be divided. 



Again, as the brachial artery occasionally deviates from its accustomed 

 place in the arm, it is prudent, before beginning an operation on the living 

 body, to be assured of its position by the pulsation. Should the vessel be 

 thus displaced, it has the ordinary coverings of the brachial artery, except at 

 the lower part of the arm, where some fibres of the pronator teres will re- 

 quire to be divided in an operation for securing the vessel. 



When the brachial artery is double, or when two arteries are present in 

 the arm, both being usually placed close together, they are accessible in the 

 same operation. The circumstance of one being placed over the fascia 

 (should this very unfrequent departure from the usual arrangement exist) 

 will become manifest in the examination which ought to be made in all cases 

 before an operation is begun. And, as regards the occasional position of one 

 of the two arteries beneath a stratum of muscular fibres, or its removal to 

 the inner side of the arm (in a line towards the inner condyle of the hume- 

 rus), it need only be added that a knowledge of these exceptional cases will 

 at once suggest the precautions which are necessary, and the steps which 

 should be taken when, they are met with. The foregoing observations have 

 reference to operations on the brachial artery, above the bend of the elbow ; 

 the surgical anatomy of the vessel opposite that joint requires a separate 

 notice. 



Fig. 700. 



Fig. 700. SUPERFICIAL DISSECTION OF THE 

 BLOOD-VESSKLS AT THE BEND OP THE ARM 

 (from R. Quain). 



a, two branches of the internal cutaneous 

 nerve ; a', a', the descending twigs of the same 

 nerve ; &, placed over the biceps near its in- 

 sertion and close to the external cutaneous nerve ; 

 &', anterior twigs of the same nerve accompany- 

 ing the median vein ; 1, placed on the fascia 

 near the bend of the arm, above the place where 

 it has been opened to show the lower part of the 

 brachial artery with its venae comites, of which 

 one is entire, marked 2, and the other has been 

 divided ; +, is placed between this and the 

 median nerve ; 3, basilic vein ; 3', 3', ulnar 

 veins ; 4, cephalic vein ; 4', radial vein ; 5, 5, 

 median vein ; 3', 5, median basilic vein ; 4', 5, 

 median cephalic vein. 



At the bend of the elbow the disposition 

 of the brachial artery is chiefly, or, at 

 least, most commonly, of interest in a 

 surgical point of view, because of its con- 

 nection with the veins from which blood 

 is usually drawn in the treatment of 

 disease. The vein (median basilic) which 

 is generally the most prominent and 

 apparently best suited for venesection 

 is commonly placed over the course of 

 the brachial artery, separated from it 



only by a thin layer of fibrous structure (the expansion from the tendon of 

 the biceps muscle) ; and under such circumstances, it ought not, if it can be 



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