Esophagus (Gullet)

Anatomy overview

The esophagus or gullet consists of a muscular tube through which food passes from the pharynx to the stomach. In humans, the esophagus is continuous with the laryngeal part of the pharynx at the level of the C6 vertebra. Here we find the upper esophageal sphincter which consists of striated muscle and yet, is not under conscious control. During swallowing, the upper esophageal sphincter opens reflexively so the bolus can pass into the esophagus. Food is passed through the esophagus by using the process of peristalsis. Specifically, it connects the pharynx which is the body cavity that is common to the digestive and respiratory systems with the stomach  where the second stage of digestion is initiated.

The esophagus is lined with a mucous membrane consisting of squamous epithelium, and a submucosa containing the mucous secreting glands, and connective structures termed papillae.  The epithelium of the oesphagus has a relatively rapid turnover, and serves a protective function due to the high volume transit of food, saliva and mucus.

While historically the gullet mucosa derived from gut mucosa with secretory and reabsorptive functions, it was later covered and replaced by ectodermal tissue governed by the cerebral cortex in the upper 2/3 of the organ. Here, we also find a layer of striated muscle. The lower part is lined with smooth muscle, that acts through peristaltic action to move swallowed food down to the stomach. The swallowing sound that we hear is the esophagus at work. The esophagus ends at the mouth of the upper stomach with a functional sphincter (not muscle tissue), avoiding that gastric juice enters and damages esophagus mucosa.

Brain

Relay:

Brain Stem (+/-) dorsal right: for Endodermal Mucosa (Lower 1/3 of the gullet) and Cardiac sphincter, and
Midbrain (+/-) dorsal right: for Smooth muscle layer (Smooth organ muscle, lower half of the gullet)

Cerebral Medulla (-/+) “thoracic area” left & right: for Striated muscleand Submucosa/Connective Tissue

Cerebral Cortex (-/+) insular region medial left & right below coronary relays: for Ectodermal Mucosa(Upper 2/3 of the gullet)