THE COMMON CAROTID ARTERY 



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PLAN OF THE RELATIONS OF THE COMMON CAROTID ARTERY. 



Integument and superficial fascia. 



Deep cervical fascia. 



Platysma. 



Sternomastoid. 



Sternohyoid. 



Sternothyroid. 



Externally. 

 Internal jugular vein. 

 Vagus nerve. 



In front. 



Longus colli. 



Hectus capitis anticus major. 



Behind. 



Recurrent laryngeal nerve. 



Omohyoid. 



Descendens and communicans hypoglossi 



nerves. 



Sternomastoid artery. 

 Superior and middle thyroid veins. 

 Anterior jugular vein. 



Internally. 



Trachea. 



Thyroid gland. 



Recurrent laryngeal nerve. 



Inferior thyroid artery. 



Larynx. 



Pharynx. 



Sympathetic cord. 

 Inferior thyroid artery. 



On the posterior aspect of the angle of bifurcation of the common carotid is a reddish-brown 

 oval body known as the carotid gland. (See Ductless Glands.) 



Peculiarities as to Origin. The right common carotid may arise above or below the upper 

 border of the sternoclavicular articulation. This variation occurs in one out of about eight 

 cases and a half, and the origin is more frequently below than above; or the artery may arise 

 as a separate branch from the arch of the aorta or in conjunction with the left carotid. The 

 left common carotid varies more frequently in its origin than the right. In the majority of abnor- 

 mal cases it arises with the innominate artery, or, if the innominate artery is absent, the two 

 carotids arise usually by a single trunk. It rarely joins with the left subclavian, except in cases 

 of transposition of the arch. 



Peculiarities as to Point of Division. In the majority of abnormal cases this occurs higher 

 than usual, the artery dividing into two branches opposite the hyoid bone, or even higher; more 

 rarely it occurs below, opposite the middle of the larynx or the lower border of the cricoid car- 

 tilage; and one case is related by Morgagni where the common carotid, only an inch and a 

 half in length, divided at the root of the neck. Very rarely the common carotid ascends in the 

 neck without any subdivision, the internal carotid being wanting; and in a few cases the com- 

 mon carotid has been found to be absent, the external and internal carotids arising directly 

 from the arch of the aorta. This peculiarity existed on both sides in some instances, on one 

 side in others. 



Occasional Branches. Each common carotid usually gives off no branch previous to its 

 bifurcation; but it occasionally gives origin to the superior thyroid or its laryngeal branch, the 

 ascending pharyngeal, the inferior thyroid, or, more rarely, the vertebral artery. 



Surface Marking. The course of each common carotid artery is indicated by a line drawn 

 .from the sternal end of the clavicle below, to a point midway between the angle of the mandible 

 and the mastoid process above. That portion of the line below the level of the upper border 

 of the thyroid cartilage would represent the course of the vessel. 



Applied Anatomy .The operation of tying the common carotid artery may be necessary 

 in a case of wound of that vessel or its branches, in aneurism, or in a case of pulsating tumor of 

 <he orbit or skull. If the wound involves the trunk of the common carotid, it will be necessary 

 to tie the artery through the wound above and below the wounded part. If the wound is too 

 .small to admit of safe and rapid work it must be enlarged. In cases of aneurism, or where one 

 of 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, in the great majority of cases, the internal jugular 

 vein 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 appli- 

 cation 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 



