1080 



THE EESPIKATOEY SYSTEM. 



Left common 

 carotid artery 



Vagus nerve 



Left snbclavian artery 



Thoracic duct 



Left common 

 carotid artery 



Pleura 



Vagus nerve 

 L. subclavian artery 

 Left recurrent nerve 



Thyreoid gland 

 Trachea 



Common carotid artery 



Inferior thyreoid artery 

 Recurrent nerve 



Innominate artery 

 Vagus nerve 



Pleura 



Trachea 



(Esophagus 



Phrenic nerve 



Thoracic duct 



cervical fascia and integument, separate the cervical part of the trachea from the 

 surface. In the median plane of the neck there is a narrow diamond-shaped space 

 between the medial margins of these muscles, within which the trachea is covered 

 merely by the integuments and fasciae. It is important to note that in the inferior 



part of the neck the cervical 

 fascia is in two layers viz., 

 a strong stratum applied to 

 the ventral surface of the 

 sterno-hyoid and sterno-thy- 

 reoid muscles, and a weaker 

 superficial layer stretching 

 across between the two 

 sterno-cleido-mastoid mus- 

 cles. Dorsal to these muscular 

 and fascial layers the inferior 

 thyreoid veins pass down- 

 wards on the ventral surface 

 of the trachea, and sometimes 

 the occasional thyreoidea 

 ima artery passes upwards 

 on the ventral aspect of the 

 tube. At the superior border 

 of the manubrium sterni the 

 innominate artery may be 

 seen crossing the trachea 

 obliquely. 



The thoracic part of the 

 trachea is situated in the 

 dorsal part of the superior 

 mediastinum, being separated 

 from the bodies of the ver- 

 tebrae by the oesophagus alone. 

 Immediately above its bi- 

 furcation the deep cardiac 

 plexus of nerves is placed 

 on the ventral and lateral 

 aspects of the trachea. At the 

 level of the fourth thoracic 

 vertebra the aortic arch is 

 very intimately related to it, 

 lying first on the ventral 

 side of the tube, and there- 

 after on its left side. The 

 three great vessels which 

 spring from the aortic arch 

 are also placed in close 

 proximity to the trachea. 

 The innominate and the left 

 common carotid arteries lie 

 at first ventral to the trachea, 

 and then gradually diverging 



as they proceed upwards, 

 CQme to He Qn either gide O f 



it the innominate to the 

 right, and the left common carotid to the left. Ventral to these vessels are the 

 left innominate vein and the remains of the thymus. On the right side the 

 thoracic part of the trachea is in relation to the right vagus nerve, and is clothed 

 by the right mediastinal pleura ; on the left side are the left subclavian artery and 

 the left recurrent nerve. 



(Esophagus 



Thoracic duct 



Vagus 



Aorta 



Thoracic duct 



Vagus nerve 



Intercostal arteries 

 Vena azygos 



Bifurcation 

 of trachea 



' Eparterial bronchus 

 Vagus nerve 

 Bronchial artery 



Vena azygos 

 CEsophagus 



FIG. 859. TRANSVERSE SECTIONS through the trachea and its imme- 

 ** ^ ^ f **** of ^e upper five thoracic 



