Common Carotid Artery 23 



clavian, and ascends obliquely behind the manubrium to the clavicular 

 joint. 



To mark out the root of the artery. As the transverse sternal ridge 

 corresponds to the lower part of the transverse aorta (p. 1 79), a line 

 drawn across the manubrium at about a thumb's breadth above that 

 ridge marks the upper border of the arch. The innominate artery 

 springs from the middle of that line ; the left carotid, therefore, comes 

 from a little to the left of the middle of the line, and mounts to the 

 inner end of the clavicle. 



To mark the course of the common carotid artery in the neck, the 

 shoulders should be raised and the head thrown back, the face being 

 slightly turned to the opposite side. A line is then drawn from the 

 sterno-clavicular articulation to the interval between the condyle of 

 the jaw and the mastoid process. This line, up to the level of the 

 upper border of the thyroid cartilage, corresponds to the common, and 

 above that to the external carotid. 



The groove in the side of the neck running along the anterior 

 border of the sterno-mastoid is the surgeon's guide to the artery. The 

 higher that the vessel mounts in the neck, the more superficial it be- 

 comes, because the sterno-mastoid passes backwards from it, whilst 

 the sterno-hyoid and thyroid have left it upon the inner side. There- 

 fore the surgeon, who is free to choose, prefers to tie it in the upper 

 part of its course, that is, above the omo-hyoid, which crosses at the 

 level of the cricoid cartilage. 



Remembering that all the large veins incline towards the right side 

 of the median line the right side of the heart being the venous side 

 the left internal jugular vein in its descent through the lower part of 

 the neck gradually gets to the front of the common carotid, whilst the 

 right vein slopes away from the outer side of its artery, to descend in 

 front of the right subclavian artery. 



Rule. Above the level of the diaphragm the large veins are upon a 

 plane anterior to the arteries ; below that level they are on a posterior 

 plane, with one exception (p. 356). 



The carotid artery may be compressed with the employment of 

 a slight force against the transverse process of the sixth cervical 

 vertebra the carotid tubercle. This may readily be made out a 

 little below the level of the cricoid cartilage, in the situation of 

 the carotid sheath, that is beneath the anterior border of the sterno- 

 mastoid. 



The level of the fifth cervical vertebra is an important station 

 in the anatomy of the neck : it corresponds pretty nearly to the site 

 at which the omo-hyoid crosses the carotid sheath, and to the position of 

 the cricoid cartilage thus marking the ending of the larynx and the 

 beginning of the trachea, the ending of the pharynx and the beginning 

 of the cesophagus. At that level also the inferior thyroid artery crosses 

 inwards behind the sheath of the carotid, whilst the sympathetic cord, 



