732 HUMAN ANATOMY. 



ficial, — i.e., least supported by overlying muscle ; and (r) because of the increased 

 resistance to the blood-current at that point. It is seen oftener in the right carotid 

 than in the left. Pressure-symptoms : pain in the side of the neck, face, and head 

 in the distribution of the superficial cervical plexus of nerves ; duskiyiess or mottling 

 of the skin from pressure on the sympathetic ; dyspncea and cough from lateral 

 deflection of the larynx and trachea ; defective vision, vertigo, or stupor from press- 

 ure on the internal jugular ; hoarseness or apho7iia from implication of the recurrent 

 laryngeal nerve ; dysphagia from direct pressure on the oesophagus, or — possibly, 

 together with irregular heart action, vomiting, or asthmatic rcspiratioti — from press- 

 ure on the pneumogastric. 



Digital compression may be used in a case of stab wound or in the treatment 

 of aneurism (a) by making pressure backward and outward beneath the anterior 

 edge of the sterno-mastoid muscle at the level of the cricoid cartilage, so as to flatten 

 out the artery against the transverse process of the sixth cervical vertebra (carotid 

 tubercle) about two and a half inches above the clavicle. As the vertebral artery at 

 this level enters its canal in the foramina of the transverse processes, it will probably 

 escape pressure. The internal jugular vein is usually displaced laterally. The 

 common carotid artery may also be effectually compressed in cases of wound {b) by 

 grasping the anterior edge of the sterno-mastoid and the artery together between 

 the thumb and fingers, or (c) by placing the thumb beneath the artery and the 

 anterior edge of the muscle, and the fingers along its posterior edge. In all three of 

 these methods it is necessary to flex the head and turn it a little towards the affected 

 side so as fully to relax the sterno-mastoid. 



Ligation. — It may be necessary to tie the common carotid in cases of (a') aneu- 

 rism, including certain pulsating tumors of the orbit or scalp or within the cranium ; 

 {b) hemorrhage from wound of the neck, or from pharyngeal wound or ulceration ; 

 or {c) for the prevention of bleeding during some operations. Whenever ligation 

 of the external carotid satisfactorily meets the indications, it is better to tie that 

 vessel {q.v.), as the cerebral circulation is not thereby interfered with. 



The lower portions of the common carotids on both sides of the neck are deeply 

 seated ; they are covered by three planes of muscles (the sterno-mastoid, sterno- 

 hyoid, and sterno-thyroid) ; the inferior thyroid artery and recurrent laryngeal nerve 

 run behind them on each side, and on the left side the internal jugular vein usually 

 passes from without inward in front of the artery, which is also in close relation to 

 the thoracic duct, the innominate artery, and the left innominate vein. 



Two operations for ligation of the common carotid may be described : i. The 

 place of election for the application of a ligature is just above the omo-hyoid muscle, 

 where the artery has become more superficial and is covered only by the skin, the 

 platysma, the fasciae, and the anterior edge of the sterno-mastoid. The skin incision 

 — three inches in length — is made in the line of the vessel, the centre being placed 

 opposite the anterior arch of the cricoid cartilage. It divides also the platysma. 

 The deep fascia is divided, and the anterior edge of the sterno-mastoid is exposed 

 and followed downward to the angle between it and the upper edge of the omo- 

 hyoid muscle. The former muscle is then drawn outward, the latter downward, the 

 descendens hypoglossi nerve avoided, the sterno-mastoid branch of the superior 

 thyroid artery and the superior — and sometimes the middle — thyroid vein held aside 

 or tied, and the sheath opened over the carotid compartment, — i.e., well to the 

 inner side, — so as to avoid injury to the larger internal jugular vein, which some- 

 times — as in cases of embarrassed respiration- — bulges over the artery so as com- 

 pletely to obscure it. The needle should be passed from without inward to avoid 

 injury to the vein, care, of course, being taken not to include the vagus. 



2. Below the omo-hyoid muscle the skin incision — three inches in length — still 

 follows the anterior border of the sterno-mastoid, beginning now a little below the 

 lower border of the cricoid cartilage and ending just above the sterno-clavicular 

 articulation. A second incision along the upper border of the clavicle is often advis- 

 able. The sterno-mastoid is drawn outward and the outer edge of the sterno-hyoid 

 muscle exposed, and that muscle, with the sterno-thyroid, drawn downward and 

 inward. Frequently the sternal portion of the sterno-mastoid, and occasionally the 

 sterno-hyoid and sterno-thyroid muscles also, will require division if the ligature has 



