NECK. 



579 



of the scaleni, it would appear, instead of 

 having, as its fellow has, a certain length of 

 transverse course, to bend abruptly toward the 

 arch of the aorta, becoming deeper and deeper; 

 or, in other words, while the right subclavian 

 has a considerable extent at its highest level, 

 from the sterno-clavicular joint to the scalene 

 space, the left has comparatively but a cul- 

 minating point, to which it suddenly rises and 

 from which it quickly sinks. Thus the nerves, 

 which cross the course of the right, are nearly 

 parallel to that of the left : and the relation of 

 the jugular vein is similarly changed, while the 

 subclavian vein, having a longer course than 

 on the right side, obliquely crosses the thoracic 

 portion of its artery. 



The anatomy of the veins requires some sepa- 

 rate notice: in crossing the scalenus anticus at 

 its insertion, the nubclav tan vein is, on both sides, 

 anterior to the artery, from which the tendon di- 

 vides it, and somewhat inferior to it ; the jugular 

 vein in the upper part of the neck descends as 

 already mentioned, beside the internal and com- 

 mon carotid arteries, to which it is external, 

 similarly on both sides. The union of these 

 veins, however, to form the venee innominatae 

 differs in the following manner. On the right 

 side, the jugular vein, inclining from its artery 

 below, joins the subclavian on the insertion 

 of the scalenus anticus : the arrangement of 

 these important parts is such that they form 

 together an elongated triangle, of which the 

 carotid artery is the inner side, the jugular vein 

 the outer, and the first stage of the subclavian 

 the base, here crossed at a right angle by the 

 pneumogastric nerve, (which reflects its recur- 

 rent branch upward and inward behind the 

 artery,) and more outwardly by the phrenic : 

 from this point of junction the innominata vein 

 runs toward the pericardium on the pulmonic 

 side of its artery, that is, externally to it and 

 on an inferior plane. On the opposite side the 

 jugular vein, anticipating its ultimate destina- 

 tion, obliquely bends toward the right side, 

 overlapping the carotid artery, in front of 

 which it receives the subclavian vein by its 

 outer side : the resulting vena innominata 

 sinistra runs almost transversely across the arch 

 to join its fellow at the right extremity of this. 

 The vertebral vein opens into the innominata, 

 just internally to the confluence which forms 

 that trunk. On the left side it crosses the sub- 

 clavian artery : on the right side it is usually, 

 though not always, behind it. 



The thoracic duct, mounting from the medi- 

 astinum, passes behind the arch, emerges be- 

 tween the carotid and subclavian arteries in 

 the root of the neck, and, curving abruptly 

 downwards, outwards, and forwards, crosses the 

 latler artery and discharges its contents by a 

 valvular opening into the subclavian vein close 

 to the angle of its confluence with the jugular. 



The surgical relations of this region regard 

 the subclavian artery and the operations which 

 are practised on it. Of these the most usual 

 is its ligature on the outside of the scalene 

 space, where lying upon the upper surface of 

 the rib. An incision, corresponding to the 

 middle of the clavicle, through the skin, super- 



ficial fascia, and platysma, and through the 

 strong single layer of cervical aponeurosis 

 which is fixed to the bone, extending, if neces- 

 sary, to the origin of the sterno-mastoid and to 

 its sheath, with careful avoidance of the ex- 

 ternal jugular vein, here bending round the 

 outer edge of the muscle, opens a space, where- 

 in loose cellular tissue alone veils the conti- 

 nuation of the pre-vertebral fascia, which is 

 prolonging itself from the scaleni around the 

 subclavian vessels : a division of this lamina, 

 as near as possible to the costal attachment of 

 the scalenus anticus, completes the exposure 

 of the artery, which is recognised by the finger, 

 as it emerges from behind the tendon of that 

 muscle, in immediate contact, with the rib. 

 The steps of the operation thus considered 

 seem of no great difficulty, and are, in fact, 

 so long as the parts retain their normal bear- 

 ings, of extremely easy performance: the artery 

 is at an inconsiderable depth ; its relations are 

 singularly definite and unembarrassed. But 

 such is not their practical facility, under cir- 

 cumstances which necessitate the operation. 

 To lie the subclavian artery for axillary aneu- 

 rism may be one of the most difficult opera- 

 tions in surgery, involving extieme patience 

 and much manual skill in him who undertakes 

 it ; for the disease, as it extends, not only fills 

 the axilla, but encroaches on the neck, thrust- 

 ing up the clavicle, and obliterating the in- 

 terval between that bone and the omo-hyoid 

 muscle. The operation might almost be com- 

 pared to one of tying the axillary artery in its 

 normal relations from above the clavicle. It 

 lies at the bottom of a deep and narrow cavity, 

 in which the operator must be guided entirely 

 by the sense of touch, and can only apply this 

 under the disadvantage of distance. The cir- 

 cumstances of such a case are well given by 

 the late Mr. Todd of Dublin,* who states 

 that, " so much was the relation of parts al- 

 tered by the magnitude of the tumour and 

 consequent elevation of the clavicle, that the 

 omo-hyoid was situated an inch below this 

 bone, and it was found necessary to draw it 

 up from its concealment, and to cut it across, 

 that the subjacent parts might become acces- 

 sible." It must be under the influence of 

 such changes that the aneurismal sac, by en- 

 croaching on the very seat of the operation, 

 becomes liable to injury, and may, as I have 

 witnessed, be actually transfixed by the needle. 

 The relation of the brachial plexus is com- 

 monly such that it lies on a plane posterior to 

 the artery, and for the greater part above it; 

 occasionally, however, its last root passes in 

 front of the vessel, and in the disguised con- 

 dition of parts is not readily to be distin- 

 guished from it ; since the touch fails in its 

 ordinary discrimination, where exercised with 

 so much difficulty, and it is hardly practicable 

 to apply the test of compression to the sup- 

 posed arterial trunk, in the view of ascertain- 

 ing its relation to the tumour, without un- 

 intentionally extending the same pressure to 

 the subjacent artery and mis-informing one's- 



* Dublin Hospital Reports, vol. iii. 



: r 2 



