46 TOPOGRAPHICAL ANATOMY OF THE 



The main ventral relations of the trachea in the thorax are the 

 bicarotid trunk, the brachio-cephalic artery, the common brachio- 

 cephalic trunk and the cranial vena cava. Along the ventral border of 

 each lateral surface runs a recurrent nerve. To the left the trachea is 

 related to the left subclavian and costo-cervical arteries, the thoracic 

 duct and the aorta. Close to the thoracic inlet the oesophagus also lies 

 to the left of the trachea, but later it becomes dorsal in position. 



The right vagus nerve runs along the right face of the trachea, and 

 this surface is crossed by the costo-cervical trunk and vertebral artery 

 and the corresponding veins, and the vena azygos, as well as by 

 sympathetic nerves. 



Dorsally the trachea is at first in contact with the longus colli 

 muscle, and later with the oesophagus. 



Of the bronchi,^ the right is the wider and shorter, and is in contact 

 with the vena azygos ; the left bronchus is related to the aorta, and is 

 crossed dorsally by the oesophagus. 



A group of lymph glands (lymphoglandulfe bronchiales), previously 

 noted, generally more or less pigmented, will be found about the 

 bifurcation of the trachea. 



The (ESOPHAGUS. — The oesophagus ^ enters the chest along with and 

 to the left of the trachea. This relationship is maintained for a little 

 distance, but later the oesophagus, inclining to the right, becomes dorsal 

 to the trachea and crosses its bifurcation in the median plane of the 

 body. Having traversed the postcardial mediastinum, the tube leaves 

 the thorax by the hiatus oesophageus of the diaphragm on a level with 

 the thirteenth thoracic vertebra. Its relations on the left are the first 

 rib, the roots of the left brachial plexus, sympathetic ganglia, the 

 vertebral, deep cervical and costo-cervical arteries, the thoracic duct and 

 the aortic arch. On the right it is crossed by the vena azygos. 



The gullet and the vagus nerves are intimately related to each other. 



It should be noted that the wall of the oesophagus is red in colour 

 until the neighbourhood of the tracheal bifurcation is reached, after 

 which it is pale. 



Pale muscular fibres are often described as connecting the oesophagus 

 to the trachea and left bronchus (m. bronchooesophageus} on the one 

 hand, and the vertebral column (m. pleurooesophageus) on the other. 



A chain of small lymph glands (lymphoglandulfe mediastinales 

 caudales) lies along the oesophagus in the postcardial mediastinum. 



N. VAGUS. — The right and left vagus ^ nerves descend the neck in 



1 j8/)67xos (bronchos) [Gr.], windpipe. 



2 oiffeii' Coi.sein) [Gr.], to cany. <pa.-yr)iia (pha^^enia) [Gr.], food. 



3 Vagus [L.], wandering, rambling. The nerve "wanders" from the head, down 

 the neck and through the tliorax into the abdomen. 



