Oesophagus

The esophagus is a muscular tube that connects the pharynx to the stomach, facilitating the passage of ingested materials.

In mammals, the esophagus typically consists of three parts: cervical, thoracic, and abdominal. The muscular composition of the esophagus varies along its length. In many domestic mammals, the proximal (upper) part of the esophagus is composed of striated muscle, which transitions to smooth muscle in the distal (lower) part. For example, in dogs, the esophagus is predominantly striated muscle throughout its length, while in cats, the distal portion contains smooth muscle.[1-3]

The esophageal wall is composed of several layers: the mucosa, submucosa, muscularis externa, and adventitia. The mucosa is lined by non-keratinized stratified squamous epithelium, which provides protection against mechanical damage. The submucosa contains esophageal glands that secrete mucus to lubricate the esophagus and facilitate the passage of food. The muscularis externa consists of an inner circular and an outer longitudinal muscle layer, which are responsible for the peristaltic movements that propel food towards the stomach.[4-5]