2090
The esophagus commonly known as the foodpipe.
It consists of a hollow muscular tube through which food passes from the pharynx to the stomach.
It is continuous with the laryngophaeynx.
Average diameter of the muscular canal of 2 cm. with approximately 25 cm length from pharynx to stomach.
Passes behind the trachea, left mainstem bronchus, left atrium and left ventricle and passes through the diaphragm.
It passes through the posterior mediastinum in the thorax and enters the stomach through a hole in the thoracic diaphragm—the esophageal hiatus, at the level of the tenth thoracic vertebra (T10).
Extends from C6 vertebra to T11-T12 vertebra.
For endoscopic identification the esophagus is measured from the incisor teeth with the gastrointestinal junction at the 40 cm point.
Appears narrowed at the cricoid cartilage, alongside the aortic arch and at the anterior crossing of the left mainstem bronchus and left atrium and where it pierces the diaphragm.
Originates at the level of the cricoid cartilage and usually ends below the hiatus in the right crura of the diaphragm.
The lumen pressure is negative compared to the atmosphere.
Intraluminal pressure elevated in two areas: the 3 cm proximal esophagus at the level of the cricopharyngeal muscle, the upper esophageal sphincter, and the 2-4 cm segment just proximal to the gastro esophageal junction, at the diaphragm, the lower esophageal sphincter.
The upper and lower esophageal sphincters are not anatomic but physiologic in nature.
The esophagogastric junction mechanism consist of a lower esophageal sphincter made up of smooth muscle, and the crural diaphragm made up of skeletal muscle.
The above sphincters are referred to as an internal and external lower esophageal sphincter, respectively.
Its wall consists of mucosa, submucosa, muscularis propria and adventitia.
Mucosa made up of nonkeratinizing stratified squamous epithelial layer, lamina propria, an muscularis mucosa.
Esophageal muscularis mucosa there is firm sparse bundles of smooth muscle in the cervical region to a thickened with reticulated network in the distal esophagus.
Small numbers of melanocytes, endocrine cells, lymphocytes and dendritic cells are present in the deep layers of the epithelium.
Lamina propria is nonepithelial section of the mucosal surface consisting of connective tissue, vascular structure and neutrophils.
The lamina propria consists of areolar connective tissue with blood vessels and few leukocytes.
Papillae extensions of the lamina propria enter into the epithelial layer.
The muscularis mucosae contains longitudinally oriented smooth muscles.
The muscularis propria consists of an inner circular and an outer longitudinal layer of smooth muscle with intervening myenteric plexus, the Auerbach plexus.
The muscularis propria gradually changes from skeletal muscle in the upper esophagus to primarily smooth muscle in the distal esophagus, with a mix of muscle types along the length of the esophagus.
The esophagus has both circular and longitudinal muscle layers and within the diaphragmatic hiatus there is thickened circular muscle layer 2 to 4 cm in size, the lower esophageal sphincter.
The esophagus is innervated with both parasympathetic and sympathetic nerves.
Peristalsis in the esophagus is regulated via the parasympathetic pathway from the Vegas nerve and the intrinsic enteric nervous system.
The proximal esophageal muscularis propria of 6-8 cm contains striated muscle from the cricopharyngeal muscle.
The esophagus, unlike the remainder of the gastrointestinal tract, lacks a serosa except for the intraabdominal esophagus.
The submucosa has loose subcutaneous tissue with blood vessels, lymphatic, leukocytes, lymphoid follicles, nerve fibers, and submucosal glands.
Submucosal glands connect to the lumen by squamous cell lined ducts are scattered along the length of the esophagus with a concentration at the upper and lower ends.
The submucosal glands contain mucin which lubricate the esophagus.
The thoracic esophagus is surrounded by fascia forming a sheath around the esophagus, the tracheobronchial tree and the great vessels.
Proximate to surrounding vital structures allows dissemination of infections and malignancies of the esophagus to the posterior mediastinum.
Lymphatics run in the mucosal and submucosal tissues along the length of the esophagus and facilitates spread of malignancy and infection.
Conducts food and fluids from the pharynx to the stomach.
Prevents passive diffusion of food substances into the blood stream.
Prevents reflux of gastric material into the esophagus.
Peristalsis is coordinated with the swallowing mechanism with relaxation of the lower esophageal sphincter during peristalsis and closing of the sphincter after the swallowing reflex.
Esophageal function is complex and requires neural coordination with the oropharynx and transition to different anatomical areas with mixed muscle types.
Food or liquid entering the esophagus undergoes primary peristalsis down the length of the esophagus.
Peristalsis contractions in the striated muscle depends on central mechanism that involves sequential activation of excitatory activity of lower motor neurons in the vagaries nucleus ambiguus.
Motor function requires intrinsic and extrinsic innervation of muscles and humoral regulation.
Excitation is mediated by release of acetylcholine at the motor iand plates.
During deglutition muscularis propria muscle fibers are actively inhibited by nonadrenergic/noncholinergic neurons, and tonic excitation by cholinergic neurons is stopped, resulting in the relaxation of the lower esophageal sphincter.
Gastrin, acetylcholine, serotonin, prostaglandins, motilin, substance P, histamine, and pancreatic polypeptide can increase the lower esophageal sphincter tone.
Vasoactive intestinal peptide and nitric oxide can decrease the tone of the lower esophageal sphincter.
Ectopic tissue rests, with gastric ectopic mucosa, is present in the upper esophagus in up to 2% of people.
Ectopic gastric mucosa can lead to acid secretions with localized inflammation.
Congenital cysts with duplication cysts can be seen in the lower esophagus.