-ADDITIONAL PRACTICAL OBSERVATIONS.
It yet remains, in conclusion, briefly to review some circumstances in the anatomy of the neck, which particularly bear on its dis eases and on the operations undertaken for their cure. 1. In endeavouring to form a diagnosis of tumours in this region, the surgeon will, in the first place, remember their extreme liability to deceptive pulsation, and will neg lect no precaution for ascertaining their rela tion to the large arterial trunks. The glands, which lie about the common and external ca rotid arteries, in the anterior triangle of the neck, and those vvhich are situated in the supra-clavicular space, are particularly subject, when enlarged, to derive pulsation from the vessels to which they are respectively conti guous. The history of the case,—the signs afforded by auscultation,—the manner in which a non-aneurismal tumour may frequently be moved away from the artery that communi cates an impulse to it,—the marked difference even to the unpractised hand, between the mere jerk of elevation in the one case, and the thrilling diastole in the other, are materials for distinction, to which it is here enough to allude. Nor must it be forgotten, that, from the near ness of the aortic arch to the root of the neck, its aneurisms, as they grow upwards and clear the strait of the thorax, may simulate the cha racters of a like disease in the carotid or sub clavian artery. Cases constantly occur, (and may be found abundantly quoted in systematic surgical works,) in which tuinours of this kind, rising in the vicinity of the sterno-clavicular articulation, have been mistaken for aneurisms of the innoininata, on the one side, or of the carotid or subclavian on the other, according as they have, in their growth, deviated right or left from the median line. Burns records a case, in which an aneurism so originating from the aorta, was even falsely attributed to the right subclavian: it bulged first on the acromial side of the sterno-mastoid muscle, " a point, where no one would expect a tumour to present, which had worked its way from within the chest." This is an extreme and rare instance; but not so are the misapprehensions, previously alluded to: it is certain, and matter of frequent experience, that aneurisms of the arch, where they escape from the resisting stricture of the sternum and clavicles, project so abruptly, as to have the appearance of belonging to the artery, over which their fundus is situated.
They frequently have (as in the case which Burns quotes from Sir Astley Cooper) a Flo rence-flask-like form, the neck of which may be narrow, and the fundus high in the neck. In several such closes the deception has been so complete, as to suggest to the surgeon the propriety of tying the common carotid below its supposed aneurism :t but no instance is on record, as I believe, of the adoption of so calamitous a proceeding. It is, indeed, true and almost self-evident that an aneurismal swelling, famed at the root of the carotid, will commonly first be perceived in the small interval between the heads of the sterno-mas toid, and, in its further growth, may displace these, or cause their absorption :—that one connected with the arteria innorninata is likely to project nearer to the trachea, and on the inner side of the sterno-mastoid :—that one originating from the subclavian will usually rise on the outer side of the same muscle ; and that the force of the pulse is generally diminished in the branches of a trunk affected with aneurism :/ yet, while such facts may have their weight, as excluding certain tumours from the respective categories of subelavian, carotid, or innuminata aneurism, and as so assisting the negative diagnosis of these diseases,—it admits of no doubt that they are insufficient to establish grounds for positive recognition. The aortic aneurism may imitate every circumstance of position in the neck, which has been men tioned ; and can hardly fail by its abnormal pressure to affect the circulation through the contiguous artery, and to weaken the pulse of its branches. To other criteria, than the mere symptom of external prominence, the cautious surgeon will look for a safe diagnosis of swell ings in the root of the neck. The minutest inquiry into the history of the patient during the period, which preceded any outward pro jection of the tumour, and into the actual state of his thoracic organs and of their functions (with notice of every pain, palpitation, or dys pricea),—an observation of any existing impe diment to the retum of blood, as evidenced by venous congestion,*— and complete and careful stethoscopy, are all requisite to that stray cf the particular case, which alone can justify an opinion.