ascends here; and since, from the angle of the jaw to the base of the skull, it lies beside the pharynx, covered by the lateral parts of that cylinder, it is liable to be involved in a punctured wound from the mouth; and this unfortunate accident has not unfrequently occurred in operations on the tonsil, which organ in its swollen state is so closely applied to the internal carotid artery, that if it were transfixed by a bistoury in an outward direction, the vessel could hardly escape. Hence the importance of care, in relieving tonsillary abscesses, to direct the point of the instrument, as much as possible, towards the median line, and to select for incision that part of the cyst which most nearly adjoins the palate. The jugular vein emerges behind the artery and runs downwardly along its outer side: of the three divisions of the eighth nerve, which leave the cranium in front of the vein, the glosso-pharyngeal is applied to the outer, the vagus and spinal accessary to the inner part of its circumference. The muscular branch of the latter winds from within behind the vein, and obliquely descends to the sterno-mastoid: the vagus continues to descend vertically along its inner side, but both the glosso-pharyngeal and hypo-glossal nerves obliquely cross between it and the artery, and subsequently arch over the latter in their passage to the tongue. From its relations to the vertebræ in this space, the pharynx may participate in their diseased conditions, and give vent to abscesses, dependent on caries of the cervical spine. The surgeon may sometimes assist his diagnosis of complaints so situated, by introducing his linger into the pharynx.[1]
8. Lastly, I proceed to recapitulate, briefly and in connexion, the practical relations of the sterno-cleido-mastoideus in regard of the spaces which have been described. Its clavicular origin is in the inferior division of the posterior triangle, covers the subclavian artery in the first and second portions of its course, and in many instances extends this origin so for outwardly as to hide the vessel during a considerable part of its third stage; it likewise, of course, covers many parts lying between it and the artery,—the jugular and subclavian veins, the vagus and phrenic nerves, the scalenus anticus and omo-hyoid muscles, and the origin and divergence of many arterial branches: these fibres obviously require division, varying according to circumstances, when the subclavian artery is to be exposed. The interval between its origins corresponds to the sterno-clavicular joint, and, on the right side, to the bifurcation of the arteria innominata: along the cellular line, prolonged from this interval, (which answers to the diagonal dividing the two great triangles,) M. Sedillot proposes to penetrate, without section of muscular fibre, in order to reach the common carotid artery. The sternal head of the muscle, directing itself backward, obliquely crosses, in the inferior segment of the great anterior triangle, the sheath of the vessels, from which the sub-hyoid muscles partly divide it. In order to reach the common carotid artery these fibres are accordingly cut asunder, except where the operator prefers the anatomical finesse of M. Sedillot's plan. Tracing the muscle in the middle of the neck, we find it a most serviceable guide in operations on the common carotid, and on its primary or secondary branches. A vertical incision directed to the point of its intersection with the omo-hyoid muscle (nearly opposite the cricoid cartilage) enables the surgeon conveniently to draw these muscles aside, and to expose, according as the wound is higher or lower, the external and internal carotids, or the trunk from which they originate, and, in close connexion with the anterior layer of their sheath, the descending branch of the hypo-glossal. Finally, about and above the level of the hyoid bone, the anterior edge of the sterno-mastoid, with the posterior belly of the digastric, and the cornu of the os hyoides, furnish definite marks for discovering the superior thyroid, the lingual, the facial or the continued external carotid artery; since, in the space so bounded, the last named vessel vertically ascends, the first almost horizontally advances, and the other two pass to their destinations with intermediate obliquity.
IV.—ADDITIONAL PRACTICAL OBSERVATIONS.
It yet remains, in conclusion, briefly to review some circumstances in the anatomy of the neck, which particularly bear on its diseases 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 neglect no precaution for ascertaining their relation to the large arterial trunks. The glands, which lie about the common and external carotid arteries, in the anterior triangle of the neck, and those which are situated in the supra-clavicular space, are particularly subject, when enlarged, to derive pulsation from the vessels to which they are respectively contiguous. 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 communicates 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 nearness 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 characters of a like disease in the carotid or subclavian artery. Cases constantly occur, (and may be found abundantly quoted in systematic surgical works,) in which tumours of this kind,
- ↑ A case has lately occurred to the writer illustrating this fact. It was one of neuralgia; the pain was of extreme severity and obstinacy; it affected the occipital region, and was referred to the great occipital nerve. An examination through the pharynx succeeded in detecting, as its probable cause, a firm (apparently bony) tumour, connected with the transverse processes, between which that nerve emerges.
