234 THE VISCERA. 
Actton.—Constrictor of the pharynx. 
3. The Csophagus.—_The cesophagus is a straight tube, 
dorsoventrally flat when empty, which extends from the 
pharynx to the stomach. It has a uniform diameter when 
moderately dilated of about one centimeter. It lies dorsad of 
the trachea and against the longus colli muscles (Fig. 72, g’) 
covering the centra of the cervical vertebre, until it reaches 
the caudal end of the thyroid gland (Fig. 96, 6); then it passes 
to the left and lies Jaterodorsad of the trachea until it reaches 
the bifurcation of the trachea. It there returns to the median 
line, passes gradually distad, separated from the vertebre by 
the aorta, and finally pierces the diaphragm about two centi- 
meters from the dorsal body wall, and enters the stomach. Its 
attachment to the diaphragm is loose enough to permit of longi- 
tudinal motion. In passing through the thoracic cavity it lies 
in the posterior mediastinum ventrad of the aorta. Its wall 
consists of a muscular coat, a submucosa, and a mucosa, and 
its inner surface presents many longitudinal folds. It has no 
serous covering, its side walls being merely in contact with the: 
halves of the mediastinal septum. 
4. The Stomach. Ventriculus (Fig. 97).—The stomach 
is the widest part of the alimentary canal. It is a pear-shaped 
sac, the long axis of which is curved nearly into a semicircle. 
The broad end of the sac lies to the left and dorsad; here the 
stomach communicates with the cesophagus (a). The narrowed 
end extends to the right and lies more ventrad than the other 
end; it passes here into the duodenum (g). That portion of 
the stomach which communicates with the cesophagus is known 
as the cardiac end (0); the opposite is the pyloric end. Owing 
to the curved form of the stomach above mentioned it is possi- 
ble to distinguish a concave and a convex side. The concave 
side is directed craniad and dextrad; it is called the lesser 
curvature of the stomach (c). The longer convex border is 
directed caudad and to the left; it is called the greater curva- 
ture (7). The greater curvature extends to the left, next to 
the cesophagus, into a prominent convexity known as the 
fundus (¢) of the stomach. 
The stomach lies at the cranial end of the abdominal 
