The esophagus or oesophagus (see spelling differences), sometimes known as the gullet, is an organ in vertebrates which consists of a muscular tube through which food passes from the pharynx to the stomach. The word esophagus is derived from the Latin œsophagus, which derives from the Greek word oisophagos , lit. "entrance for eating." In humans the esophagus is continuous with the laryngeal part of the pharynx at the level of the C6 vertebra. The esophagus passes through a hole in the diaphragm at the level of the tenth thoracic vertebrae (T10). It is usually about 25–30 cm long and connects the mouth to the stomach. It is divided into abdominal parts.
The layers of the esophagus are as follows:
mucosa (mucus)
nonkeratinized stratified squamous epithelium: is rapidly turned over, and serves a protective effect due to the high volume transit of food, saliva and mucus.
lamina propria: sparse.
muscularis mucosae: smooth muscle
submucosa: Contains the mucous secreting glands (esophageal glands), and connective structures termed papillae.
muscularis externa (or "muscularis propria"): composition varies in different parts of the esophagus, to correspond with the conscious control over swallowing in the upper portions and the autonomic control in the lower portions:
upper third, or superior part: striated muscle
middle third, smooth muscle and striated muscle
inferior third: predominantly smooth muscle
adventitia
The junction between the esophagus and the stomach (the gastroesophageal junction or GE junction) is not actually considered a valve, although it is sometimes called the cardiac sphincter, cardia or cardias, although it is actually better resembles a stricture.
In most fish, the esophagus is extremely short, primarily due to the length of the pharynx (which is associated with the gills). However, some fish, including lampreys, chimaeras, and lungfish, have no true stomach, so that the oesophagus effectively runs from the pharynx directly to the intestine, and is therefore somewhat longer.
In tetrapods, the pharynx is much shorter, and the esophagus correspondingly longer, than in fish. In amphibians, sharks and rays, the esophageal epithelium is ciliated, helping to wash food along, in addition to the action of muscular peristalsis. In the majority of vertebrates, the esophagus is simply a connecting tube, but in birds, it is extended towards the lower end to form a crop for storing food before it enters the true stomach.
A structure with the same name is often found in invertebrates, including molluscs and arthropods, connecting the oral cavity with the stomach
In most fish, the esophagus is extremely short, primarily due to the length of the pharynx (which is associated with the gills). However, some fish, including lampreys, chimaeras, and lungfish, have no true stomach, so that the oesophagus effectively runs from the pharynx directly to the intestine, and is therefore somewhat longer.crimeajewel.
In tetrapods, the pharynx is much shorter, and the esophagus correspondingly longer, than in fish. In amphibians, sharks and rays, the esophageal epithelium is ciliated, helping to wash food along, in addition to the action of muscular peristalsis. In the majority of vertebrates, the esophagus is simply a connecting tube, but in birds, it is extended towards the lower end to form a crop for storing food before it enters the true stomach.
A structure with the same name is often found in invertebrates, including molluscs and arthropods, connecting the oral cavity with the stomach
Globus pharyngis (also known as globus sensation, globus or, somewhat outdatedly, globus hystericus; commonly referred to as having a "lump in one's throat") is the persistent sensation of having phlegm or some other sort of obstruction in the throat when there is none. Swallowing can be performed normally, so it is not a true case of dysphagia, but it can become quite irritating. One may also feel mild chest pain or even severe pain with a clicking sensation when swallowing.
The "lump in the throat" sensation that characterizes globus pharyngis is often caused by inflammation of one or more parts of the throat, such as the larynx or hypopharynx, due to Cricopharyngeal Spasm, gastroesophageal reflux or oesophageal dysmotility.
In some cases the cause is unknown and symptoms may be attributed to a psychogenic cause i.e. a somatoform or anxiety disorder. It has been recognised as a symptom of depression, which responds to anti-depressive treatment.
A less common cause, distinguished by a "lump in the throat" accompanied with clicking sensation and considerable pain when swallowing, maybe due to thyroid-cartilage rubbing against anomalous asymmetrical laryngeal anatomy e.g. the superior cornu abrading against the thyroid lamina,surgically trimming the offending thyroid-cartilage provides immediate relief in all cases. However this cause is frequently misdiagnosed, despite requiring a simple clinical examination involving careful palpation of the neck side to side which elicits the same click sensation (laryngeal crepitus) and pain as when swallowing, most cases are due to prior trauma to the neck. High resolution computed tomographic (CT) or MRI scan of the larynx is usually required to fully understand the anomalous laryngeal anatomy. Anterior displacement the thyroid ala on the affected side while swallowing can help resolve symptoms.
