aa itn 
THE G&SOPHAGUS. 991 
uncovered. It is generally described as lying against the a@sophageal groove and the left lateral 
ligament of the liver in front, but it never actually comes in contact with the latter of these 
structures, which is attached to the upper surface of the left lobe of the liver hy one edge, and 
to the diaphragm, over an inch in front of the @sophagus, by the other. As regards the former, 
the esophageal groove of the liver is generally occupied by the prominent right margin of the 
cesophageal orifice of the diaphragm, and occasionally by the cesophagus as well. Possibly this 
margin is so strongly developed and so prominent in order that it may bear the pressure of the 
liver off the gullet, which otherwise would be interfered with in its dilatation during the passage 
of food. . 
When the stomach is fully distended the abdominal part of the cesophagus almost disappears, 
being absorbed into the stomach in its distension. Indeed, it is possible that it is in most 
eases an artificial production, due to the traction on the empty stomach (generally necessary to 
demonstrate 1t) pulling a part of the a@sophagus from its lax diaphragmatic moorings down 
into the abdominal cavity. 
Variations.—The chief anomalies found in the cesophagus are: (1) Annular or tubular con- 
strictions ; (2) diverticula, of which the most interesting—known as “ pressure pouches ”—are 
usually situated on the posterior wall close to its junction with the pharynx, and these some- 
times require surgical interference ; (3) doubling in part of its course ; and (4) communications 
between the trachea and cesophagus. 
Structure of the G:sophagus (Fig. 669).—The wsophageal wall is composed of 
three proper coats—(1) muscular, (2) submucous, and (3) mucous. In addition, it is sur- 
rounded by an outer covering of areolar tissue (tunica 
adventitia), by which it is loosely connected to the \ | 
various structures related to it in its course. This ! 
loose covering permits of its free movement and of its 
increase in size, or of its diminution, during the act 
of swallowing. j 
The muscular coat (tunica muscularis) is composed 
of two layers—an outer of longitudinal, and an inner 
of circular fibres. The longitudinal layer is highly 
developed, and, unlike the condition usually found 
in the digestive tube, it is as stout as, or in places 
stouter than, the circular layer. Its fibres form along 
the greater length of the tube an even covering out- 
side the circular layer, and below they are continued 
into the longitudinal fibres of the stomach. Above, 
near the upper end of the cesophagus, the longitudinal 
fibres of each side, separating at the back, pass round 
towards the anterior aspect, and form two longitudinal 
bands (Fig. 667), which run up on the front of the tube, 
and are attached by a tendinous band to the upper part 
of the back of the cricoid cartilage (Fig. 668). 
Inferior 
constrictor 
The circular muscular Sibres, though not forming Longitudinal / Teton 
such a thick layer as the longitudinal fibres, are never-_ fibres diverging 
theless well developed. Below they are continued into pyc, 667.—DissEcTION to show the 
both the circular and oblique fibres of the stomach. arrangement of the muscular fibres 
Above they pass into the lower fibres of the inferior on the back of the cesophagus and 
pharynx. Traced upwards, the lon- 
gitudinal muscular fibres of the 
cesophagus are seen to separate 
constrictor of the pharynx. 
The muscular fibres are entirely of the striated 
variety at the upper end of the csophagus. Soon behind ; passing round to the sides, 
unstriped fibres begin to appear, increasing in number they form two longitudinal bands 
which meet:in front above, and are 
united to the cricoid cartilage, as 
shown in the next figure. 
as we descend. In the lower half or two-thirds, only 
unstriped muscle is found. 
The longitudinal fibres for about the upper fifth of 
the tube are entirely striped ; in the second fifth striped and unstriped are mixed ; whilst 
in the lower three-fifths unstriped fibres alone are present. The circular fibres are 
entirely striated for the first inch; after this unstriped fibres appear; and in the lower 
two-thirds, only unstriped muscles are found (D. J. Coffey), 
The longitudinal fibres are often joined by slips of unstriped muscle, or elastic fibres, 
which spring from various sources, including the left pleura (constant, Cunningham), the 
bronchi, back of trachea, pericardium, aorta, etc. These slips assist in fixing the esophagus 
to the surrounding structures in its passage through the thorax, and have been aptly 
compared to the tendrils of a climbing plant (Treitz). 
The submucous coat, composed of areolar tissue, is of very considerable thickness, in 
order to allow of the expansion of the tube during swallowing. It connects the mucous 
