1. Defect And Excess

It is only necessary to allude to the congenital absence of this passage as occurring in acephalous monsters, to its partial defect with a blind termination, its fusion with the trachea, to the saccular dilatation of the canal resembling the craw of a bird, to its being double in disomatic monsters, and to the very rare occurrence of insulated fissures in individuals that are otherwise normally built (Meckel).

2. Acquired Abnormities Of Tlie Calibre, And The Thickness Of The Parietes

Anomalies of the calibre present themselves in the shape of dilatations or contractions.

Dilatation may affect the pharynx and oesophagus throughout, or almost throughout, and give them a cylindrical or a fusiform appearance; when it affects the oesophagus, it may be partial, in which case either pouches are formed, which involve all the coats of the oesophagus, and which may be developed at all points of its circumference; or the mucous membrane alone dilates, giving rise to diverticula or hernise of the mucous membrane through the muscular coat.

The first variety has only been observed in a few cases, though when it occurs it is developed to an advanced degree, and presents thickening of the parietes, and particularly hypertrophy of the muscular coat. It appears to be sometimes the consequence of concussion of the cesophagus by a blow or contusion of the chest. One preparation, in the Viennese collection, presents an oesophagus large enough to allow the passage of a man's arm; in another case (Hanney), the circumference of the dilated passage was six inches.

Dilatations of a lower degree sometimes occur, in which the oesophageal coats are in a condition of paralytic relaxation and attenuation.

The second variety is seen at various points, and in various degrees, above contractions, and especially above scirrhous strictures.

The third variety is rounded; or, if it increases to a considerable size, we find cylindrical or conical dilatations of the mucous membrane, occupying the lateral portions of the oesophagus. They may form at all parts of the oesophagus, but they are most frequently seen near the bifurcation of the trachea, and they attain the greatest size at the inferior section of the pharynx (Baillie), where the fibres of the inferior constrictor have a horizontal position. The mucous membrane is protruded between the muscular fibres, and becomes dilated by the food that enters; it is at last forced out in the shape of a cylindrical appendix, which lies between the vertebral column and the oesophagus, in a line with the axis of the pharynx, so that all ingesta pass into it, and death from starvation results.

The origin of the diverticulum is in many cases peculiar; thus we are acquainted with an instance in which the mucous membrane of the oesophagus was dragged out in consequence of the shrivelling of an adherent tracheal gland.

The fauces and the oesophagus are not unfrequently subject to contraction, from being compressed by the enlarged thymus gland, by aortic aneurisms, adventitious growths, etc.; but the contractions resulting from textural changes in the coats are of more importance, and among these we must more particularly allude to stenoses brought on by cicatrization after corrosion by caustic substances, and by cancerous affections (cancerous stricture). Of both we shall have further occasion to speak in the sequel.

3. Anomalies Of Position

Among these we may reckon the position of the oesophagus to the right of the spinal column, accompanying a lateral transposition of the intestines, the changes produced by curvatures of the spine, the flexures or dislocations of the pharynx and oesophagus, brought about by hypertrophy of the thyroid gland, by aneurisms, abscesses, morbid growths, etc.

4. Solutions Of Continuity

Among these we reckon, besides wounds of the pharynx and oesophagus, by means of fire-arms, or other penetrating instruments, the injuries and perforations caused by foreign bodies that have been swallowed, the perforations from softening, ulcerations, gangrene, or from absorption in consequence of pressure, e. g., by aneurisms, by which means the most various passages, communicating with the neighboring serous cavities, the respiratory organs, the adjoining vascular trunks, etc, may be established, and lastly, those very rare occurrences of spontaneous rupture, without previous alteration in the tissue.

6. Foreign Bodies

Sometimes small hard bodies, such as cherrystones, give rise to serious occurrences, by causing, at different parts of the oesophagus, but chiefly at the lower constrictor of the pharynx (Bail-lie), the formation of diverticula. Very large and hard bodies, such as are sometimes swallowed by lunatics, remain fixed at a certain spot, and may cause inflammation and suppuration; or, by extreme pressure, even give rise to gangrene and perforation of the oesophagus. Pointed and rough bodies, and especially needles and fish bones, are still more likely to produce perforations of the oesophagus in different directions, and to reach the aorta or trachea.