408 ARTERIES. 



Varieties in Muscular Relations. 1 The brachial artery is occasionally concealed, in some part 

 of its course, by muscular or tendinous slips derived from various sources. In the upper third 

 of the arm, the brachial vessels and median nerve have been seen concealed to the extent of 

 three inches by a muscular layer of considerable thickness, derived from the Coraco-brachialis, 

 which passed round to the inner side of the vessel, and joined the internal head of the Triceps. 

 In the lower half of the arm it is occasionally concealed by a broad thin head to the Biceps 

 muscle (see p. 303). A narrow fleshy slip from the Biceps has been seen to cross the artery, 

 concealing it for an inch and a half, its tendon ending in the aponeurosis covering the Pronator 

 teres. A muscular and tendinous slip has been seen to arise from the external bicipital ridge 

 by a long tendon, cross obliquely behind the long tendon of the Biceps, end in a fleshy belly, 

 which appears on the inner side of the arm between the Biceps and Coraco-brachialis, passes 

 down along the inner edge of the former, and crosses the artery very obliquely, so as to lie in 

 front of it for three inches, and, finally, end in a narrow flattened tendon, which is inserted into 

 the aponeurosis over the Pronator teres. A tendinous slip, arising from the deep part of the 

 tendon of the Pectoralis major, has been seen to cross the artery obliquely at or below the 

 Coraco-brachialis, and join the intermuscular septum above the inner condyle. The Brachialis 

 anticus not unfrequently projects at the outer side of the artery, occasionally overlaps it, sending 

 inwards, across the artery, an aponeurosis which binds the vessel down upon the Brachialis 

 anticus. Sometimes a fleshy slip from the muscle covers the vessel, in one case, to the extent 

 of three inches. In some cases of high origin of the Pronator radii teres, an aponeurosis extends 

 from it to join the Brachialis anticus external to the artery; a kind of arch being thus formed, 

 under which the principal artery and median nerve pass, so as to be concealed for half an inch 

 above the transverse level of the condyle. 



Surgical Anatomy. Compression of the brachial artery is required in cases of amputation of 

 the arm or forearm, in resection of the elbow-joint, and the removal of tumors ; and it will be 

 observed, that it may be effected in almost any part of its course ; if pressure is made in the upper 

 part of the limb it should be directed from within outwards, and if in the lower part from before 

 backwards, as the artery lies on the inner side of the humerus above, and in front of it below. 

 The most favorable situation is either above or below the insertion of the Coraco-brachialis. 



The application of a ligature to the brachial artery may be required in cases of wounds of the 

 vessel, or in wounds of the palmar arch, where compression of the radial and ulnar arteries fails to 

 arrest the hemorrhage. It is also necessary in cases of aneurism of the brachial, the radial, ulnar, 

 or interosseous arteries; and it may be secured in any part of its course. The chief guides in 

 determining its position are the surface-markings produced by the inner margin of the Coraco- 

 brachialis and Biceps, the known course of the vessel, and its pulsation, which should be care- 

 fully 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 muscular fibre is met with concealing the artery; if such is the case, it must be 

 divided across, in order to expose the vessel. 



In the upper third (f the arm the artery maybe exposed in the following manner : The patient 

 being placed horizontally 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 ulnar side of the 

 Coraco-brachialis muscle, and the subjacent fascia cautiously divided so as to avoid wounding the 

 internal cutaneous nerve or basilic vein, which sometimes run on the surface of the artery as high 

 as the axilla. 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 venas comites are also 

 in relation with the vessel, one on either side. These being carefully separated, the aneurism 

 needle should be passed round the artery from the ulnar to the radial side. 



If two arteries are present in the arm in consequence of a high division, they are usually placed 

 side by side ; and if they are exposed in an operation, the surgeon should endeavor to ascertain, 

 by alternately pressing on one or the other 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 

 towards the inner condyle of the humerus, or in its usual position, but deeply placed beneath the 

 common trunk : a knowledge of these facts will at once suggest the precautions necessary in 

 every case, and indicate the necessary measures to be adopted when 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 

 jying upon the artery, sometimes beqeath ; this being drawn inwards and the muscle outwards, 



1 STRUTHEB'S Anatomical and Physiological Observations. 



