ABSTRACT
The anatomy of the gastrointestinal system has been described in detail in the literature (Schantz et al., 1996; Yen, 2001) and in Chapter 1. The oral cavity is described in Chapter 10. In this section, the anatomy important to surgical procedures is discussed, and views of the intestinal viscera
in situ
are illustrated in Figure 4.1-Figure 4.3. The esophagus originates from the pharynx at the second cervical vertebra and passes along
the left side of the trachea. The muscularis mucosa is composed of inner circular and outer longitudinal layers which are composed of striated muscle fibers in the proximal 50% which progress to smooth muscle fibers. In humans, only the distal of the esophagus has smooth muscle cells. The mucosa is stratified squamous epithelium throughout the length. The esophageal diameter in domestic swine 10-50 kg ranges from 15 to 20 mm, and in Yucatan swine 45-50 kg, the range is 12-14 mm.
