THE TRACHEA AND BRONCHI 



1181 



muscular and inner fibrous layers, and pass through the submucous and mucous layers to open 

 on the surface of the mucous membrane. Some glands of smaller size are also found at the 

 sides of the trachea, between the layers of fibrous tissue connecting the rings, and others imme- 

 diately beneath the mucous coat. The secretion from these glands serves to lubricate the inner 

 surface of the trachea. 



Vessels and Nerves. The trachea is supplied with blood by the inferior thyroid arteries. 

 The veins terminate in the thyroid venous plexus. The nerves are derived from the vagus and 

 its recurrent branches and from the sympathetic. 



Lymph Nodes. The trachea is surrounded by lax connective tissue which contains nu- 

 merous lymph nodes, known as the peritracheobronchial nodes. They are divided into four 

 groups (Barety). A group to the right side, in the angle between the trachea and right bronchus 

 and ascending to the region of the subclavian vessels. A group to the left side, in the angle 

 formed by the trachea and left bronchus, and ascending to about the arch of the aorta and the 

 recurrent laryngeal nerve. The two groups just described are usually called tracheal nodes 

 (lymphoglandttlae trackeales). A third group is in the angle formed by the bifurcation of the 

 trachea. These constitute the bronchial nodes (It/mphoglandulae bronchioles}, ten or twelve in 



RIGHT TRACHEAL 

 LYMPH NODES 



RIGHT SUPERIOR 



TRACHEO- 



BROIMCHIAL 



LYMPH NODES 



LEFT TRACHEAL 

 LYMPH NODES 



LEFT SUPERIOR 

 TRACHEO- 

 BRONCHIAL 

 LYMPH NODES 



Vl 



BRONCHO- 

 PULMONARY 

 LYMPH NODES 



INFERIOR 



TRACHEO-BRONCHIAL 

 LYMPH NODES 



FIG. 896. The tracheobronchial and bronchopulmonary lymph nodes, seen from in front. The dotted 

 lymph nodes and lymph vessels are not visible from in front: rf 1 , cf 2 . First and second dorsal branch bronchi, v 1 . v 2 . 

 First and second ventral branch bronchi. (Sukiennikow.) 



number. A fourth group, the interbronchial nodes, are found in angles of bifurcation of the 

 larger bronchi in the lung parenchyma. Very early in life the peritracheobronchial nodes 

 become dark or even black from the deposition of carbonaceous substance brought by the leuko- 

 cytes from the bronchial tubes. This condition is called anthracosis. 



Surface Form. In the middle line of the neck some of the cartilages of the larynx can readily 

 be distinguished. In the angle below the chin the hyoid bone can easily be distinguished, and 

 a finger's breadth below it is the pomum Adami, the prominence between the upper borders of 

 the two alae of the thyroid cartilage. About an inch below this, in the middle line, is a depres- 

 sion corresponding to the cricothyroid space, in which the operation of laryngotomy is per- 

 formed. This depression is bounded below by a prominent arch, the anterior ring of the cricoid 

 cartilage, below which the trachea can be felt, though it is only in the emaciated adult that the 

 separate rings can be distinguished. The lower part of the trachea is not easily observed, for 

 as it descends in the neck, following the curvature of the vertebral column, it takes a deeper 

 position, and is farther removed from the surface. The level of the vocal cords corresponds to 

 the middle of the anterior margin of the thyroid cartilage. 



With the laryngoscope, the following structures can be seen. The base of the tongue and 

 the upper surface of the epiglottis, with the glossoepiglottic ligaments; the superior aperture of 



