THE NECK. 141 



deep fascia of the neck splits to enclose the sternomastoid muscle it is opened by 

 the operation and infection has caused in such cases wide-spread phlegmonous 

 inflammation. 



ARTERIES OF THE NECK. LIGATION. 



Carotid and Subclavian Arteries and Branches. Both these arteries are 

 affected at times with aneurisms, necessitating their ligation. Ligation of the main 

 trunks or their branches is also required in various operations on the head, as in re- 

 moval of the Gasserian ganglion or maxilla, or excision of the tongue, thyroid gland, 

 etc. The communication between the arteries on the two sides of the body is quite 

 free, as also is that between the arteries above and those lower down. For this 

 reason bleeding from the distal end of a cut artery will be almost as free as from its 

 proximal end. The various branches of the external carotid anastomose across the 

 median line of the body. The vertebrals communicate above through the basilar. 

 The internal carotids communicate through the anterior cerebral and anterior com- 

 municating and with the basilar through the posterior communicating and posterior 

 cerebral. Between the parts above and those below we have the superior thyroid 

 anastomosing with the inferior thyroid branch of the thyroid axis from the subclavian 

 artery. The princeps cervicis, a branch of the occipital, anastomoses with the as- 

 cending cervical branch of the inferior thyroid, the transverse cervical of the thyroid 

 axis, and the profunda cervicis from the superior intercostal. These free communi- 

 cations enable the surgeon to ligate to any extent without incurring the risk of gan- 

 grene. The line of the carotid arteries is from a point midway between the mastoid 

 process and the angle of the jaw to the sternoclavicular articulation. At the upper 

 border of the thyroid cartilage the common carotid divides into the internal and ex- 

 ternal carotids; this is opposite the fifth cervical vertebra. 



Common Carotid Artery. This lies on the longus colli muscle and a small 

 portion of the rectus capitis anticus, which separate the artery from the transverse 

 processes of the vertebrae. The artery can be compressed against the vertebrae and 

 its pulsations stopped by pressing backward and slightly inward. It is superficial in 

 the upper portion of its course but becomes deeper as' it approaches the chest. The 

 anterior tubercle of the transverse process of the sixth cervical vertebra is called 

 Chassaignac' s tubercle. It is about opposite the cricoid cartilage. It is one of the 

 guides to the artery. The omohyoid muscle crosses the artery opposite the cricoid 

 cartilage and just above it is the site of election for ligation. 



Ligation of the Common Carotid Artery. In making the incision, which should 

 be 5 or 6 cm. long, it should be laid along the anterior edge of the sternomastoid 

 muscle with its middle opposite to or a little above the level of the cricoid cartilage. 

 This incision may be a little anterior to the direct line of the artery as given from 

 midway between the angle of the jaw and mastoid process to the sternoclavicular 

 articulation. This is because the muscle bulges forward and overlaps and hides the 

 artery. The artery is beneath its edge. On cutting through the superficial fascia and 

 platysma the deep fascia is reached, some small veins perhaps being divided in 

 so doing. The deep fascia is divided along the edge of the sternomastoid muscle, 

 which is then pulled outward. Beneath it and running obliquely across the lower 

 portion of the wound is the omohyoid muscle. It is recognized by the direction of 

 its fibres, they being more or less transverse or oblique. Sometimes a small artery, 

 the sternomastoid branch of the superior thyroid, crosses the common carotid just 

 above the omohyoid muscle. The artery is also crossed by veins. The lingual, 

 superior, and middle thyroid veins all pass over it to enter the internal jugular. 

 The middle thyroid vein may be above or just below the omohyoid muscle. 

 These vessels all pass transversely across the artery and beneath the deep fascia. 

 The artery lies in a separate sheath to the inner side of the jugular vein. In the 

 living body it is to be recognized by its pulsations. The vein being filled with blood 

 may overlap the artery. Veins are readily emptied of their blood by pressure on 

 the parts during the operation; hence if the vein happens to be collapsed it may not 

 be recognized and is liable to be wounded. Therefore in examining for the artery see 

 that the pressure from the retractors or other sources does not obstruct the flow of 



