550 THE ARTERIES. 



the branches of the common carotid is wounded in an inaccessible situation, it may be judged 

 necessary to tie the trunk. In such cases the whole of the artery is accessible, and any part may 

 be tied except close to either end. When the case is such as to allow of a choice being made, 

 the lower part of the carotid should never be selected as the spot upon which to place a ligature, 

 for not only is the artery in this situation placed very deeply in the neck, but it is covered 

 by three layers of muscles, and, on the left side, the internal jugular vein, in the great majority 

 of cases, passes obliquely in front of it. Neither should the upper end be selected, for here the 

 superior thyroid vein and its tributaries would give rise to very considerable difficulty in the 

 application of a ligature. The point most favorable for the operation is that part of the vessel 

 which is at the level of the cricoid cartilage. It occasionally happens that the carotid 

 artery bifurcates below its usual position : if the artery be exposed at its point of bifurcation, 

 both divisions of the vessel should be tied near their origin, in preference to tying the trunk 

 of the artery near its termination ; and if, in consequence of the entire absence of the common 

 carotid or from its early division, two arteries, the external and internal carotids, are met with, 

 the ligature should be placed on that vessel which is found on compression to be connected with 

 the disease. 



In this operation the direction of the vessel and the inner margin of the Sterno-mastoid are 

 the chief guides to its performance. The patient should be placed on his back with the head 

 thrown back and turned slightly to the opposite side: an incision is to be made, three inches 

 long, in the direction of the anterior border of the Sterno-mastoid, so that the centre corresponds 

 to the level of the cricoid cartilage : after dividing the integument, superficial fascia, and 

 Platysma, the deep fascia must be cut through on a director, so as to avoid wounding 

 numerous small veins that are usually found beneath. The head may now be brought forward 

 so as to relax the parts somewhat, and the margins of the wound held asunder by retractors. 

 The descendens hypoglossi nerve may now be exposed, and must be avoided, and, the sheath of 

 the vessel having been raised by forceps, is to be opened to a small extent over the artery at its 

 inner side. The internal jugular vein may present itself alternately distended and relaxed ; this 

 should be compressed both above and below, and drawn outward, in order to facilitate the opera- 

 tion. The aneurism needle is passed from the outside, care being taken to keep the needle in 

 close contact with the artery, and thus avoid the risk of injuring the internal jugular vein or 

 including the vagus nerve. Before the ligature is tied it should be ascertained that nothing but 

 the artery is included in it. 



Ligature of the Common Carotid at the Lower Part of the Neck. This operation is 

 sometimes required in cases of aneurism of the upper part of the carotid, especially if the sac is 

 of large size. It is best performed by dividing the sternal origin of the Sterno-mastoid muscle, 

 but may be done in some cases, if the aneurism is not of very large size, by an incision 

 along the anterior border of the Sterno-mastoid, extending down to the sterno-clavicular articula- 

 tion, and by then retracting the muscle. The easiest and best plan, however, is to make an 

 incision two or three inches long down the lower part of the anterior border of the Sterno- 

 mastoid muscle to the sterno-clavicular joint, and a second incision, starting from the termination 

 of the first, along the upper border of the clavicle for about two inches. This incision is made 

 through the superficial and deep fascia, and the sternal origin of the muscle exposed. This is to 

 be divided on a director, and turned up, with the superficial structures, as a triangular flap. 

 Some loose connective tissue is to be divided or torn through, and the outer border of the 

 Sterno-hyoid muscle exposed. In doing this care must be taken not to wound the anterior 

 jugular vein, which crosses the muscle to reach the external jugular or subclavian vein. The 

 Sterno-hyoid, and with it the Sterno-thyroid. are to be drawn inward by means of a retractor, 

 and the sheath of the vessel is exposed. This must be opened with great care on its inner 

 or tracheal side, so as to avoid the internal jugular vein. This is especially necessary on 

 the left side, where the artery is commonly overlapped by the vein. On the right side there is 

 usually an interval between the artery and the vein, and not the same risk of wounding the 

 latter. 



The common carotid artery, being a long vessel without any branches, is particularly suitable 

 for the performance of Brasdor's operation for the cure of an aneurism of the lower part of the 

 vessel. Brasdor's procedure consists in ligaturing the artery on the distal side of the aneurism, 

 and in the case of the common carotid there are no branches given off from the vessel between 

 the aneurism and the site of the ligature ; hence little or no blood passes through the sac of the 

 aneurism, and consequently it and the vessel shrinks, and a cure is effected. 



Collateral Circulation. After ligature of the common carotid the collateral circulation 

 can be perfectly established, by the free communication which exists between the carotid arteries 

 of opposite sides, both without and within the cranium, and by enlargement of the branches of 

 the subclavian artery on the side corresponding to that on which the vessel has been tied the 

 chief communication outside the skull taking place between the superior and inferior thyroid 

 arteries, and the profunda cervicis and arteria princeps cervicis of the occipital ; the vertebral 

 taking the place of the internal carotid within the cranium. 



Sir A. Cooper had an opportunity of dissecting, thirteen years after the operation, the case 

 in which he first successfully tied the common carotid (the second case in which he performed 

 the operation). 1 The injection, however, does not seem to have been a successful one. It 

 showed merely that the arteries at the base of the brain (circle of Willis) were much enlarged on 



1 Guy's Hospital Reports, i. 56. 



