BRANCHES OF THE BRACHIAL. 595 



erally lies beneath the deep fascia, superficial to the flexor muscles : occasionally between the 

 integument and deep fascia, and very rarely beneath the flexor muscles. 



The interosseous artery BometOWB arises from the upper part of the brachial or axillary : as 

 it passes down the arm it lies behind the main trunk, and at the bend of the elbow regains its usual 

 position. 



In some eases of high division of the radial the remaining trunk (ulnar interosseous) occa- 

 sionally passes, together with the median nerve, along the inner margin of the arm to the inner 

 condyle. and then passing from within outward, beneath or through the Pronator radii teres, 

 regains its usual position at the bend of the elbow. 



Occasionally the two arteries representing the brachial are connected at the bend of the 

 elbow by a short transverse branch, and are even sometimes reunited. 



Sometimes, ling slender vessels, vasa aberrantia, connect the brachial or axillary arteries 

 with one of the arteries of the forearm or a branch from them. These vessels usually join the 

 radial. 



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

 part of its course by muscular or tendinous slips derived from the Coraco-brachialis. Biceps, 

 Brachialis anticus and Pronator radii teres muscles. 



Surface Marking. The direction of the brachial artery is marked, when the arm is 

 extended and supinated. by a line drawn from the junction of the anterior and middle third of 

 the space between the anterior and posterior folds of the axilla ; that is to say from the inner 

 side of the prominence of the Coraco-brachialis muscle to the point midway between the condyles 

 of the humerus which corresponds to the depression along the inner border of the Coraco-bra- 

 chialis and Biceps. In the upper part of its course the artery lies internal to the humerus. but 

 below it is in front of that bone. 



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

 and some other operations in the arm and forearm ; and it will be observed that it may be effected 

 in almost any part of the course of the artery. If pressure is made in the upper part of the 

 limb, it should be directed from within outward : and if in the lower part, from before backward, 

 as the artery lies on the inner side of the humerus above and in front below. The most favor- 

 able situation is about the middle of the arm. where it lies on the tendon of the Coraco-brachialis 

 on the inner flat side of the humerus. 



The application of a ligature to the brachial artery may be required in case of wound of 

 the vessel and in some cases of wound of the palmar arch. It is also sometimes necessary in 

 cases of aneurism of the brachial, the radial, ulnar, or interosseous arteries. The artery may 

 be secured in any part of its course. The chief guides in determining its position are the sur- 

 face markings produced by the inner margin of the Coraco-brachiaKs and Biceps, the known 

 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 muscular 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 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 inner 

 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 runs 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 vena? 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 inner to the outer 



s'nk'. 



If two arterit-s 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 each vessel, which of the two communicates with the wound 

 or aneurism, when a ligature may be applied accordingly ; or if pulsation or haemorrhage 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 



-ury in even- 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 



1 See Struther's Anatomical and Physiological Observations. 



