THE CESOPHAGUS 409 



Vessels and Nerves. — The arteries are derived from the common carotid, 

 external carotid, and external maxillary arteries. The lymph vessels pass to the 

 pharyngeal and anterior cervical lymph glands. The nerves are derived from the 

 trigeminus, glosso-pharyngeus, and vagus. 



THE (ESOPHAGUS 



The oesophagus is a musculo-membranous tube, about 50 to 60 inches (ca. 

 125 to 150 cm.) in length, which extends from the pharynx to the stomach. In 

 its course it shows several changes of direction. It begins in the median plane above 

 the anterior border of the cricoid cartilage of the larynx. At the fourth cervical 

 vertebra it has passed to the left side of the trachea, and continues this relation 

 as far as the third thoracic vertebra. Here it again gains the dorsal surface of the 

 trachea, and, passing backward, crosses the aortic arch, by which it is pushed over 

 to the right of the median plane. It continues in the mediastinum between the 

 lungs, backward and a little dorsally, inclining gradually to the left, and reaches 

 the hiatus oesophageus of the diaphragm. Passing through this it terminates at 

 once at the cardiac orifice of the stomach, a little to the left of the median plane, 

 and about four or five inches (ca. 10 to 12 cm.) ventral to the vertebral end of the 

 fourteenth rib.^ 



Viewed with reference to the horizontal plane, its course is downward and 

 backward till it enters the thorax and passes upward to gain the rlorsal face of 

 the trachea. Then for a short distance (i. e., to the root of the lung) its direction is 

 almost horizontal; behind this it passes somewhat upward to its termination. 

 The cervical part (Pars cervicalis) of the tube is about four to six inches (10 to 15 

 cm.) longer than the thoracic part (Pars thoracalis), while the so-called abdominal 

 part (Pars abdominalis) is about an inch (2 to 3 cm.) long.- 



The principal relations of the oesophagus at its origin are: to the cricoid 

 cartilage and dorsal crico-arj^tenoid muscles ventrally; to the guttural pouches 

 and the ventral straight muscles dorsally; and to the carotid arteries laterally. 

 In the middle of the neck the relations are: to the left longus colli muscle dorsally; 

 to the trachea medially; to the left carotid artery, vagus, sympathetic, and recurrent 

 nerves laterally. Near the thoracic inlet the oesophagus is usually in contact 

 with the left jugular vein for a short distance. At its entrance into the thorax 

 it has the trachea on its medial side; the first rib, the roots of the brachial plexus 

 of nerves, and the left posterior cervical ganglion laterally. After gaining the 

 dorsal surface of the trachea, it has the aorta on its left and the vena azygos and 

 right vagus nerve on its right side. In its course through the posterior medias- 

 tinum the cesophageal trunks of the vagus nerves lie above and below it, and the 

 oesophageal artery is dorsal to it. 



Structure. — The wall is composed of four coats: (1) A fibrous sheath termed 

 the tunica adventitia; (2) the muscular coat; (3) a submucous layer; (4) the 

 mucous membrane. The muscular coat is of the striped variety as far as the base 

 of the heart, where it rapidly changes to the unstriped type. In addition to this 

 change, the muscular coat becomes much thicker and firmer, while the lumen is 

 diminished. Except at each end of the tube the muscular coat consists chiefly of 



1 The distance between the terminal part of the oesophagus and the vertebra varies. In 

 formalin-hardened subjects it is most commonly as given above, but m soft specimens or m those 

 which have been frozen without previous fixation it is usually nearer the spme. 



2 Careful observations (especially on frozen subjects and those in which the organs have been 

 hardened in situ) show that there is no abdominal part of the oesophagus m the strict sense of the 

 term The stomach here hes directly on the diaphragm, so that the last inch or so of the oesopha- 

 gus is placed obliquely in the hiatus oesophageus, and is covered on the right and ventrally by the 

 pleura, but not by peritoneum. In soft subjects the weight of the stomach, or traction on it, draws 

 part of the oesophagus into the abdomen, inclosed in a collar of peritoneum. 



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