The esophagus is a muscular tube connecting the pharynx to the stomach. It passes through the chest cavity and
connects with the stomach just after passing through the diaphragm. The walls of the esophagus contain two layers
of striated muscles. These muscles run at right angles to each other with one layer running parallel with the esophagus.
The muscles change into smooth, involuntary muscles in the bottom one-third of the esophagus of the horse. This
occurs just in front of the diaphragm in a hog. The muscles remain striated throughout the esophagus in cattle,
sheep, and dogs.