Tracheotomy 1 3 1 



of the inferior thyroid artery ; the oesophagus and the inferior con- 

 strictor of the pharynx and the lobes of the thyroid gland are also 

 detached. 



The constrictor is then separated from the thyroid cartilage, and 

 the superior laryngeal vessels and nerve are divided. 



THE TRACHEA AND BRONCHI 



The trachea begins at the lower border of the fifth cervical 

 vertebra, and divides opposite the lower border of the fifth dorsal 

 that is, a little below the transverse sternal ridge (p. 149). It is about 

 4 in. long and f in. wide, and consists of about sixteen horse-shoe 

 cartilages connected by elastic fibres, whilst in the tissue which fills 

 the deficiency in the cartilages at the back of the trachea is a trans- 

 verse layer of non-striated muscular fibres. Probably the trachea is 

 flattened behind so that it may not encroach upon the oesophagus and 

 impede deglutition ; a foreign body impacted in the oesophagus, or 

 malignant disease, may cause fatal dyspnoea. (For Mucous MEM- 

 BRANE, v. p. 195.) 



Relations. The most constant relation of the trachea is the 

 oesophagus, which is close behind it both in the neck and in the thorax. 

 In the lateral grooves between these tubes ascend the recurrent 

 laryngeal nerves. The common carotid arteries, the lobes of the 

 thyroid body, and the inferior thyroid arteries are also to the sides. 

 In the superior mediastinum (p. 154) the trachea descends between 

 the pleurae, a pneumogastric passing on either side of it to form the 

 oesophageal and the posterior pulmonary plexuses. The innominate 

 artery is somewhat to the right, and the beginning of the left carotid 

 to the left of the trachea. 



In front are the skin and fasciae, the isthmus of the thyroid, and 

 the lowest thyroid artery and thyroid veins ; the sterno-hyoid and 

 sterno-thyroid, and some more deep fascia. Lower down the anterior 

 relations are the manubrium, the remains of the thymus, the left 

 innominate vein ; the second part of the aortic arch with the origins 

 of the innominate and left common carotid arteries, and the deep 

 cardiac plexus. 



Supply. The trachea derives its blood from the inferior thyroid 

 artery, and returns it by the lower thyroid veins. The lymphatics 

 pass to the deep cervical and the mediastinal glands. 



The nerves are branches of the vagi, the recurrent laryngeals, and 

 the sympathetic. 



Tracbeotomy. The patient's shoulders are raised on a firm pil- 

 low, and the head is thrown straight back so as to draw up and steady 

 the trachea, and to give more room to the operator. The thyroid and 

 cricoid cartilages and the upper part of the trachea are then made out 

 by the tip of the index-finger. 



The incision even in a child had better be free, from \\ to 2 in, 



K2 



