I022 A MANUAL OF ANATOMY 



the root of the left bronchus ; the posterior wall of the pericardium, 

 opposite the back of the left auricfe of the heart ; and the vertebral 

 portion of the diaphragm. Posterior. — ^The vertebral column ; the 

 longus colli muscles, especially the left ; the thoracic duct and 

 right azygos vein ; the right aortic intercostal arteries ; the upper 

 and lower transverse azygos veins ; and, interiorly, the descending 

 aorta. Right. — ^The right posterior mediastinal pleura. Left. — 

 The thoracic portion of the left subclavian artery ; the upper part 

 of the thoracic duct ; the left posterior mediastinal pleura ; and 

 the descending aorta, except interiorly. 



The right and left pneumogastric nerves are intimately related 

 to the oesophagus. They are at first disposed laterally, and their 

 branches give rise to the plexus gules. Subsequently the right 

 pneumogastric nerve descends on the posterior surface of the 

 oesophagus, and the left on the anterior surface, in which positions 

 they accompany the gullet through the oesophageal opening of the 

 diaphragm. 



Blood-supply — Arteries. — These are (i) the oesophageal branches 

 of the descending aorta, (2) the oesophageal branches of the gastric 

 artery from the coeliac axis, and (3) twigs from the left inferior 

 phrenic artery. In the neck the oesophagus receives branches 

 from the right and left inferior thyroid arteries. 



The veins accompany the corresponding arteries, and terminate 

 in the right azygos vein and the two left azygos veins. 



Lymphatics. — ^These pass to the posterior mediastinal glands. 



Nerves. — ^These are derived from the pneumogastric and sympa- 

 thetic nerves. 



Structure. — The wall of the oesophagus consists of three coats, namely, 

 muscular, submucous, and mucous. 



The muscular coat is thick, and is disposed in two layers, an external 

 longitudinal, and an internal circular. 



The longitudinal muscular fibres are attached superiorly to the upper part 

 of the median ridge on the posterior surface of the cricoid cartilage, and 

 from this point they descend as two flattened bands, one on either side of 

 the tube. These expand and soon meet, giving rise to one continuous layer 

 which completely surrounds the gullet. Inferiorly they are continuous with 

 the longitudinal muscular fibres of the stomach. Accessory fleshy slips are 

 described as passing from this layer to the back of the trachea, the back of 

 the root of the left bronchus, the pericardium, and the left pleura. 



The circular muscular fibres are continuous superiorly with the lower 

 fibres of the inferior constrictor muscles of the pharynx, and inferiorly with 

 the circular, and also with the oblique, muscular fibres of the stomach. 



The muscular tissue of the oesophagus is of the striated variety over about 

 the upper third of the tube, but elsewhere it is of the plain or non-striated 

 variety. 



The submucous coat consists of loose areolar tissue, which contains the 

 larger bloodvessels and the mucous glands. 



The mucous coat is thick, and is thrown into longitudinal folds, on account 

 of the loose disposition of the submucous coat. The portion of it next the 

 submucous coat consists of plain muscular fibres, which are arranged longi- 

 tudinally. This portion is known as the muscularis mucoscB, and it is best 

 marked in the lower part of the gullet. The inner surface of the mucous 



