THE NECK. 



163 



the trachea and wound the oesophagus behind. The trachea of a child is not the hard 

 resisting structure of the adult. It is a soft tender tube easily compressed and readily 

 torn by roughness, or punctured with a knife. Forceps do not readily hold in it and 

 stitches through it are liable to tear out. Only the very tip of the point of the knife 

 should be allowed to enter the tube. The utmost care must be taken to keep in the 

 median line. This is to be accomplished by using the cricoid cartilage as a guide 

 and by seeing that the position of the head is straight. Cutting to either side of the 

 trachea will cause wounding of the common carotid arteries. Below the isthmus of the 

 thyroid gland and running down on the trachea are the inferior thyroid veins. The 

 superior and middle thyroid veins empty into the internal jugular vein, but the 

 inferior thyroids go downward to empty into the innominate. These veins will be cut 

 if a low tracheotomy is done. In the infant the innominate artery and sometimes, 

 though rarely, the left carotid encroach on the suprasternal notch and may be wounded 

 it the incision is carried too low. The left innominate vein as it crosses to the 



Lingual and facial veins 



Internal jugular vein 



Middle thyroid veins 



Sternohyoid muscle 

 Sternomastoid muscle 

 Sternothyroid muscle 

 Anterior jugular vein 

 Inferior thyroid vein 



Hyoid bone 

 Thyroid cartilage 

 Cricothyroid muscle 



Sternohyoid muscle ) , 



. ,, ., , > drawn back 



bternothyroid muscle ) 



Superior thyroid artery and vein 

 Cricoid cartilage 

 Thyroid gland 

 Inferior thyroid artery 



Inferior thyroid vein 

 Sternomastoid muscle 



'rachea 



-ommunicating branch between the 



nterior jugular veins 



FIG. 183. Dissection showing the parts involved in operations on the thyroid gland and air-passages. 



right side is liable, especially in very young children, to show quite plainly above the 

 sternum and would certainly be cut if the deep incision was carried as far down as 

 the top of the sternum. An anomalous artery, the thyroidea ima, a branch of the 

 innominate, sometimes passes upward on the trachea. On account of the presence 

 of all these vessels it is not allowable to do any cutting of the deep parts just above 

 the sternum; they are simply to be depressed by blunt dissection and kept out of 

 the way with retractors while the trachea is being incised. The cricoid cartilage is 

 never to be incised. It is far more firm and resistant than the trachea and it serves 

 to keep the trachea from collapsing. The proximity of the tracheotomy tube to the 

 vocal cords would result in interference with their function. 



The method of Base consists in dividing the fascia overlying the trachea near 

 the cricoid cartilage and pushing it down, carrying the isthmus and veins with it, 

 and introducing the tube into the space so cleared. This is so difficult that it is 

 better to divide the isthmus, as already described. 



OPERATIONS ON THE THYROID GLAND. 



The operations which are done on the thyroid gland are ligation of its arterial 

 supply and complete or partial removal. These necessitate a knowledge particularly 

 of its blood supply and structure. 



The thyroid gland consists of an isthmtts and two lateral lobes. The isthmus 



