THE ABDOMEN. ^23 



It occasionally happens that a foreign body becomes impacted in the oesophagus, which can 

 neither be brought upwards nor moved downwards. When all ordinary means for its removal 

 have failed, excision is the only resource. This, of course, can only be performed when it is not 

 very low down. If the foreign body is allowed to remain, extensive inflammation and ulceration 

 of the oesophagus may ensue. In one case with which I am acquainted, the foreign body ulti- 

 mately penetrated the intervertebral substance, and destroyed life by inflammation of the mem- 

 branes and substance of the cord. 



The operation of cesophagotomy is thus performed. The patient being placed upon his back, 

 with the head and shoulders slightly elevated, an incision, about four inches in length, should be 

 made on the left side of the trachea, from the thyroid cartilage downwards, dividing the skin and 

 Platysma. The edges of the wound being separated, the Omo-hyoid muscle, and the fibres of 

 the Sterno-hyoid and Sterno-thyroid muscles, must be drawn inwards ; the sheath of the carotid 

 vessels being exposed, should be drawn outwards, and retained in that position by retractors ; 

 the oesophagus will then be exposed, and should be divided over the foreign body, which should 

 then be removed. Great care is necessary to avoid wounding the thyroid vessels, the thyroid 

 gland, and the laryngeal nerves. 



Structure. The oesophagus has three coats : an external, or muscular ; a 

 middle, or cellular; and an internal, or mucous coat. 



The muscular coat is composed of two planes of fibres of considerable thick- 

 ness, an external longitudinal, and an internal circular. 



The longitudinal fibres are arranged at the commencement of the tube, in three 

 fasciculi : one in front,- which is attached to the vertical ridge on the posterior 

 surface of the cricoid cartilage ; and one at each side, which are continuous with 

 the fibres of the Inferior Constrictor ; as they descend they blend together, and 

 form a uniform layer, which covers the outer surface of the tube. 



The circular fibres are continuous above with the Inferior Constrictor; their 

 direction is transverse at the upper and lower parts of the tube, but oblique in 

 the central part. 



The muscular fibres in the upper part of the oesophagus are of a red color, 

 and consist chiefly of the striped variety ; but below, they consist entirely of 

 the involuntary muscular fibre. 



The cellular coat connects loosely the mucous and muscular coats. 



The mucous coat is thick, of a reddish color above, and pale below. It is 

 disposed in longitudinal folds, which disappear on distension of the tube. Its 

 surface is studded with minute papillae, and it is covered throughout with a 

 thick layer of squamous epithelium. 



The cesophageal glands are numerous small compound glands, scattered 

 throughout the tube ; they are lodged in the subcutaneous tissue, and open 

 upon the surface by a long excretory duct. They are most numerous at the 

 lower part of the tube, where they form a ring round the cardiac orifice. 



THE ABDOMEN. 



The Abdomen is the largest cavity in the body, and is separated, below, from 

 the pelvic cavity by the brim of the pelvis. It is of an oval form, the ex- 

 tremities of the oval being directed upwards and downwards ; it is wider above 

 than below, and measures more in the vertical than in the transverse diameter. 



Boundaries. It is bounded, in front and at the sides, by the lower ribs, the 

 Transversalis muscle, and venter ilii ; behind, by the vertebral column, and the 

 Psoas and Quadratus Lumborum muscles; above, by the Diaphragm; below, by 

 the brim of the pelvis. The muscles forming the boundaries of the cavities 

 are lined upon their inner surface by a layer of fascia, differently named accord- 

 ing to the part to which it is attached. 



The abdomen contains the greater part of the alimentary canal ; some of the 

 accessory organs to digestion, viz., the liver, pancreas, and spleen; and the 

 kidneys and suprarenal capsules. Most of these structures, as well as the wall 

 of the cavity in which they are contained, are covered by an extensive and 

 complicated serous membrane, the peritoneum. 



The apertures found in the walls of the abdomen, for the transmission of 



