644 THE VASCULAR SYSTEMS 



course of the vessel, and its pulsation, which should be carefully felt for before any operation is 

 performed, as the vessel occasionally deviates from its usual position in the arm. In whatever 

 situation the operation is performed, great care is necessary, on account of the extreme thinness 

 of the parts covering the artery and the intimate connection which the vessel has, throughout its 

 whole course with important nerves and veins. Sometimes a thin layer of muscle fibre is 

 met with concealing the artery; if such is the case, it must be cut across in order to expose the 

 vessel. 



In the upper third of the arm the artery may be exposed in the following manner: The patient 

 being placed supine upon a table, the affected limb should be raised from the side and the hand 

 supinated. An incision about two inches in length should be made on the inner side of the 

 Coracobrachialis muscle, and the subjacent fascia cautiously divided, so as to avoid wounding 

 the internal cutaneous nerve or basilic vein, which sometimes runs on the surface of the artery 

 as high as the axillary. The fascia having been divided, it should be remembered that the ulnar 

 and internal cutaneous nerves lie on the inner side of the artery, the median on the outer side, 

 the latter nerve being occasionally superficial to the artery in this situation, and that the venae 

 comites are also in relation with the vessel, one on either side. These being carefully separated, 

 the aneurism needle should be passed around the artery from the inner to the outer side. 



In the case of a high division, the two arteries are usually placed side by side; and if they 

 are exposed in an operation, the surgeon should endeavor to ascertain, by alternately pressing 

 on each vessel, which of the two communicates with the wound or aneurism, when a ligature 

 may be applied accordingly; or if pulsation or hemorrhage ceases only when both vessels are 

 compressed, both vessels may be tied, as it may be concluded that the two communicate above 

 the seat of disease or are reunited. 



It should also be remembered that two arteries may be present in the arm in a case of high 

 division, and that one of these may be found along the inner intermuscular septum, in a line 

 toward the inner condyle of the humerus, or in the usual position of the brachial, but deeply 

 placed beneath the common trunk; a knowledge of these facts will suggest the precautions 

 necessary in every case, and indicate the measures to be adopted when anomalies are met with. 

 In the middle of the arm, the brachial artery may be exposed by making an incision along 

 the inner margin of the Biceps muscle. The forearm being bent so as to relax the muscle, it 

 should be drawn slightly aside, and, the fascia being carefully divided, the median nerve will be 

 exposed lying upon the artery (sometimes beneath); this being drawn inward and the muscle 

 outward, the artery should be separated from its accompanying veins and secured. In this 

 situation the inferior profunda may be mistaken for the main trunk, especially if enlarged, from 

 the collateral circulation having become established; this may be avoided by directing the 

 incision externally toward the Biceps, rather than inward or backward toward the Triceps. 



The lower part of the brachial artery is of interest from a surgical point of view, on account of the 

 relation which it bears to the veins most commonly opened in venesection. Of these vessels, 

 the median basilic is the largest and most prominent, and, consequently, the one usually selected 

 for the operation. It should be remembered that this vein runs parallel with the brachial 

 artery, from which it is separated by the bicipital fascia, and that care should be taken in opening 

 the vein not to carry the incision too deeply, so as to endanger the artery. 



Collateral Circulation. After the application of a ligature to the brachial artery in the 

 upper third of the arm, the circulation is carried on by branches from the circumflex and sub- 

 scapular arteries, anastomosing with ascending branches from the superior profunda. If the 

 brachial is tied below the origin of the profunda arteries, the circulation is maintained by the 

 branches of the profundse, anastomosing with the recurrent radial, ulnar, and interosseous 

 arteries. 





 Branches. The branches of the brachial artery are: 



Superior profunda. Inferior profunda. 



Nutrient. Anastomotica magna. 



Muscular. 



The superior profunda artery (a. profunda brachii) arises from the inner and 

 back part of the brachial, just below the lower border of the Teres major, and 

 passes backward to the interval between the outer and inner heads of the Triceps 

 muscle; accompanied by the musculospiral nerve it winds around the back part of 

 the shaft of the humerus in the spiral groove, between the outer head of the Triceps 

 and the bone, to the outer side of the humerus, where it reaches the external inter- 

 muscular septum and divides into two terminal branches. One of these pierces 

 the external intermuscular septum, and descends, in company with the musculo- 



