218 



ARM. 



brachial artery usually preserves its ordinary 

 relations to the surrounding parts, while the 

 supernumerary trunk lies to its internal side 

 and takes a more superficial course, some- 

 times getting above the fascia of the arm, as 

 we have witnessed in a few rare cases. It 

 occasionally happens that the brachial artery 

 divides at its commencement into two trunks, 

 which again unite at its lower part. It is ob- 

 vious that the surgeon, in performing operations 

 on this artery, should constantly bear in mind 

 that it is subject to the above-mentioned irre- 

 gularities, and that he should cautiously guard 

 against committing the error of including the 

 wrong vessel in his ligature. 



The internal side of the arm in the middle 

 of its length is the most eligible place for 

 making compression on the brachial artery; 

 here this vessel is superficial, so that its pul- 

 sation can be felt at once, whilst it has nothing 

 interposed between it and the bone but the 

 tendinous insertion of the coraco-brachialis 

 muscle. It happens, however, that the median 

 nerve lies immediately over the artery in this 

 situation, a circumstance which causes com- 

 pression of the latter to be attended with con- 

 siderable pain, and productive of injury to the 

 nerve if maintained for too great a length of time. 



As the trunk of the brachial artery and 

 several large nerves traverse this part of the 

 arm, it is obvious that wounds in this region 

 are liable to be attended with more serious 

 consequences than those of any other part of 

 the arm. A wound in the posterior region of 

 the arm may be attended with considerable 

 haemorrhage, if it should happen to penetrate so 

 deep as to divide the profunda artery, or it may 

 cause paralysis of the extensor muscles of the 

 hand and fingers by dividing the radial nerve. 



When the humerus is fractured, the con- 

 sequent derangement of the fragments varies 

 according to the part at which the bone hap- 

 pens to be broken ; when fracture occurs im- 

 mediately above the insertions of the pectoralis 

 major and latissimus dorsi, the lower fragment 

 is brought inward towards the axilla by the 

 action of these muscles, and drawn upwards 

 by the action of the deltoid, biceps, coraco- 

 brachialis, and long head of the triceps, whilst 

 the extremity of the upper fragment is rather 

 turned outwards by the supra-spinatus. In 

 cases where the humerus is fractured imme- 

 diately above the insertion of the deltoid and 

 below the attachments of the latissimus dorsi 

 and pectoralis tnajor, the deltoid will draw the 

 lower fragment upwards and outwards, whilst 

 the upper fragment will be drawn inwards 

 towards the axilla by the pectoralis major and 

 latissimus dorsi. If the bone be broken im- 

 mediately below the insertion of the deltoid, 

 little or no displacement of the fragments may 

 ensue, as the opposing forces exercised on the 

 superior fragment by the deltoid on the ex- 

 ternal side, and the pectoralis major and latis- 

 simus dorsi on the internal, pretty nearly 

 counterbalance each other; it more generally 

 happens, however, that the upper fragment is 

 turned outwards by the preponderating action 

 of the deltoid upon it, whilst the lower frag- 

 ment is drawn upwards by the action of the 



biceps, coraco-brachialis, and triceps. Frac- 

 tures of that portion of the humerus which is 

 covered by the brachiseus anticus in front and 

 the triceps behind, are often unattended by 

 any very obvious displacement, in consequence 

 of these muscles being inserted into both frag- 

 ments ; fractures near the elbow are occa- 

 sionally followed by deformities presenting 

 some of the characters of dislocations of the 

 elbow, of which more notice will be taken in 

 the article ELBOW. 



General inflammatory enlargement of the 

 arm is rare ; it sometimes appears as a con- 

 comitant affection with inflammation of the 

 veins of the arm consequent on the operation 

 of phlebotomy, in which case it not unfre- 

 quently happens that abscesses form along the 

 course of the sheath of the brachial artery ; 

 red streaks along the course of the lymphatics 

 and enlargement of the lymphatic glands are 

 sometimes present in consequence of disease 

 or inflammation affecting the hand or fore-arm. 



Amputation of the arm below the insertion 

 of the deltoid may be performed either by the 

 circular incision or the double flap ; when the 

 latter method is practised, the flaps should be 

 formed on the external and internal sides, by 

 which the more important vessels and nerves 

 will be included in the internal flap. 



When circumstances require the performance 

 of amputation above the insertion of the del- 

 toid, the circular operation should never be 

 practised, for the following reason ; in order 

 to obtain a sufficiency of covering for the bone, 

 the pectoralis major, latissimus dorsi, and tores 

 major would all be detached from their inser- 

 tions, a consequence of which would be that the 

 contractions of these muscles in opposite di- 

 rections, by drawing asunder the edges of the 

 wound, would not only render complete appo- 

 sition difficult in the first instance, but more- 

 over their continued action would have the 

 effect of converting the wound into an ulcer, 

 which it would be extremely difficult if not 

 impossible to heal ; therefore, whenever we 

 have to amputate so high up, it is the more 

 judicious mode of proceeding to make a flap 

 including so much of the deltoid muscle as 

 will form a sufficient covering for the stump. 

 The importance of attending to the foregoing 

 circumstances was first pointed out by Louis, 

 the learned secretary to the French Academy 

 of Surgery.* 



The arteries which require to be tied after 

 amputation of the arm below the insertion of 

 the deltoid are the brachial and inferior pro- 

 funda on the internal side ; on the external side 

 there are often two branches of the superior 

 profunda requiring a ligature, one of which 

 accompanies the musculo-spiral nerve, and the 

 other runs in the substance of the triceps. 



When it becomes necessary to tie the bra- 

 chial artery on account of a wound or aneu- 

 rism, the varieties of its relation to the median 

 nerve should be carefully borne in mind; at 

 the upper part of the arm this artery has the 

 median nerve external to it, and the ulnar 

 nerve to its inner side ; in the middle of the 



* Memoires de TAcadcmie de Chirurgic, torn. v. 



