158 APPLIED ANATOMY. 



muscle. They follow the sheath of the vessels. This is a very extensive chain of 

 nodes. They may extend in all directions. As regards depth they may be on the 

 deep fascia along the edge of the sternomastoid or following the external jugular 

 vein. If deeper they follow the internal jugular vein and carotid artery directly 

 up to the base of the skull, also behind and below the mastoid process and along- 

 side of the transverse process of the atlas (first cervical vertebra). They extend 

 under the sternomastoid posteriorly, deep in the suboccipital region. Should 

 they be enlarged downward they will protrude behind the posterior edge of the 

 sternomastoid into the posterior cervical triangle; if anteriorly they will follow it 

 down into the space of Burns in front of the trachea and thence into the superior 

 mediastinum. 



The posterior cervical nodes show behind the posterior edge of the sternomastoid, 

 along the edge of the trapezius, and also above the clavicle. They not infrequently 

 fill the posterior cervical triangle and extend beneath the muscles on each side. 



Below they may be continuous with enlarged nodes in the axilla and extend 

 anteriorly under the sternomastoid into the pretracheal region and mediastinum. 

 They are frequently excised for both tuberculosis and carcinoma. In so doing 

 particular care is to be taken on account of the transversalis colli and suprascapular 

 arteries and veins, with which they may lie in contact, as well as the terminal por- 

 tion of the external jugular. 



Postpharyngeal Nodes. In the retropharyngeal space, toward the sides, 

 between the buccopharyngeal fascia in front and the prevertebral fascia behind are 

 located one or two nodes (see buccopharyngeal fascia, page 153, and retropharyn- 

 geal abscess, page 156). They seem to be the starting point, sometimes, of retro- 

 pharyngeal abscess. They do not appear to get enlarged and project into the 

 pharynx as tumors, as might be expected, so that they are not subjected to any 

 surgical procedures. 



Operating for the Removal of Enlarged Cervical Nodes. This opera- 

 tion may be one of the most serious in surgery. Sir Frederick Treves says : " An 

 operation of this kind should not be undertaken unless the surgeon has perfect con- 

 fidence in his practical knowledge of the anatomy of the neck. Scarcely an instance 

 can be cited in the range of operative surgery where a knowledge of the structure 

 and of relations is more essential than in these excisions. ' ' The main difficulties 

 encountered are in the avoidance of nerves and the control of hemorrhage. Air 

 may enter the veins and cause death, and the thoracic duct may be wounded. The 

 latter accident sometimes results fatally. The difficulty of the operation will de- 

 pend on the size and number of the nodes, their location, and the character of the 

 inflammation or other changes they have undergone. In an early stage the nodes 

 may be lying loose in the tissues and can be readily turned out when once exposed. 

 Later they may be matted to the surrounding structures by inflammatory deposits 

 and then their separation is a matter of difficulty and danger. 



The skin incisions may be either longitudinal or more or less transverse. The 

 longitudinal incisions are usually along either the anterior or posterior border of 

 the sternomastoid muscle, or the anterior edge of the trapezius. The transverse 

 incision may be either opposite the hyoid bone when it may be prolonged around 

 the angle of the jaw and up to the mastoid process and over the suboccipital glands, 

 or above the clavicle. 



As the skin and superficial structures are cut and the deep fascia opened, 

 the superficial veins will be cut, hence the first anatomical fact to be borne in mind 

 is the probable location of the veins. The most important of these is the external 

 jugular. The internal jugular below the hyoid bone lies under the sternomastoid 

 muscle and therefore is protected until the deeper dissection is begun. The external 

 jugular runs about in a line from the angle of the jaw to the middle of the posterior 

 edge of the sternomastoid muscle and thence downward to about the middle of the 

 clavicle. Therefore an incision along the posterior edge of the sternomastoid will 

 divide it at about the middle of the muscle, and the surgeon should be prepared to 

 guard against an undue loss of blood when it is cut. Opening into the external 

 jugular posteriorly between the middle of the sternomastoid muscle and the clavicle 

 below are the posterior jugular, the transverse cervical, and the suprascapular veins. 



