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The oesophagus is a muscular tube that connects the pharynx to the stomach. It is part of the digestive system and is located in the centre of the chest, behind the trachea and heart and in front of the spine. The oesophagus is made up of several layers, including muscle layers that allow it to contract and expand, propelling food and liquid down to the stomach. The upper third of the oesophagus contains striated muscle, the lower third contains smooth muscle, and the middle third contains a mixture of both.
| Characteristics | Values |
|---|---|
| Length | 20-25 cm |
| Thickness | 0.75 mm thick under baseline resting conditions |
| Layers | Mucosa, muscularis mucosa, submucosa, muscularis propria |
| Muscles | Smooth muscle, striated muscle |
| Nerve Supply | Vagus nerve, Sympathetic trunk |
| Sphincters | Upper esophageal sphincter, Lower esophageal sphincter |
| Functions | Transport of food, liquid, and saliva to the stomach |
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What You'll Learn
The oesophagus is a hollow, muscular tube
The oesophagus is made up of several layers, including the mucosa, muscularis mucosa, submucosa, and muscularis propria. The mucosa is a mucous membrane consisting of a tough stratified squamous epithelium without keratin, a smooth lamina propria, and a muscularis mucosae. The epithelium of the oesophagus has a rapid turnover and serves a protective function against the abrasive effects of food. The submucosa contains connective tissue, lymphocytes, plasma cells, nerve cells, a vascular network, and mucous glands.
The muscularis propria, also called the muscularis externa, is the dominant muscle layer of the oesophagus. It is organised into inner circular and outer longitudinal muscle layers, each of which is several muscle cells thick. The longitudinal muscle layer originates from the dorsal, superior, and lateral margins of cricoid cartilage and surrounds the circular muscle completely. The circular muscle is continuous with the cricopharyngeus muscle, which is part of the upper esophageal sphincter (UES). The UES is a high-pressure zone situated between the pharynx and the cervical oesophagus. It is composed of circular muscle tissue and remains closed most of the time. When food enters the pharynx, it relaxes and opens, allowing food to pass through, and then immediately closes to prevent food from backing up.
The lower oesophageal sphincter (LES) is another ring-shaped muscle at the opening of the lower oesophagus. It senses when food and liquid are coming and relaxes to let them pass through to the stomach. When no food or liquid is present, it stays shut to prevent stomach acid and digestive juices from entering the oesophagus. The LES opens and closes in coordination with the UES to allow food to pass through while preventing reflux of gastric contents into the oesophagus.
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It has two sphincters, composed of circular muscle tissue
The oesophagus is a muscular tube that carries food and liquid from the throat to the stomach. It has two sphincters, composed of circular muscle tissue. The upper oesophageal sphincter (UES) is a high-pressure zone situated between the pharynx and the cervical oesophagus. It is a musculocartilaginous structure composed of the posterior surface of the thyroid and cricoid cartilage, the hyoid bone, and three muscles: cricopharyngeus, thyropharyngeus, and cranial cervical oesophagus. The UES is an anatomical, striated muscle sphincter at the junction between the pharynx and oesophagus. It is produced by the cricopharyngeus muscle and normally remains constricted to prevent the entrance of air into the oesophagus.
The lower oesophageal sphincter (LES) is located at the gastro-oesophageal junction, between the stomach and oesophagus. The gastro-oesophageal junction is situated to the left of the T11 vertebra and is marked by the change from oesophageal to gastric mucosa. The LES is a physiological or functional sphincter, as it does not have any specific sphincteric muscle. It is composed of smooth muscle and is supplied by fibres arising from the dorsal motor nucleus. The LES is responsible for preventing the reflux of gastric contents and the backflow of stomach acid and digestive juices into the oesophagus.
The UES and LES are not discernible anatomically, even on autopsy specimens. However, in vivo intraluminal ultrasound imaging in live humans has revealed thick circular and longitudinal muscle layers in the LES region. The muscle thickness varies with changes in LES pressure, suggesting that the absence of muscle tone in autopsy specimens accounts for the lack of visible thickening. The muscle layers of the oesophagus are arranged in two layers: an outer layer where the muscle fibres run longitudinally, and an inner layer where the fibres encircle the oesophagus. These layers are separated by the myenteric plexus, a network of nerve fibres involved in mucus secretion and peristalsis of the smooth muscle of the oesophagus.
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The oesophagus has two types of muscle
The oesophagus, or esophagus in American English, is a fibromuscular tube that connects the pharynx to the stomach. It is approximately 25 cm long in adults, with only about 1 cm of the oesophagus lying in the abdominal cavity. The oesophagus is innervated by the vagus nerve and the cervical and thoracic sympathetic trunk. The vagus nerve has a parasympathetic function, supplying the muscles of the oesophagus and stimulating glandular contraction.
The muscular layer of the oesophagus has two types of muscle: striated muscle and smooth muscle. The upper third of the oesophagus contains striated muscle, the lower third contains smooth muscle, and the middle third contains a mixture of both. The muscle fibres are arranged in two layers: one in which the fibres run longitudinally, and the other in which they encircle the oesophagus. These layers are separated by the myenteric plexus, a network of nerve fibres involved in mucus secretion and peristalsis of the smooth muscle.
The oesophagus is unique in that it is made up of partly skeletal (striated) and partly smooth muscles. The upper part is entirely skeletal, the middle is a mixture of both, and the lower part is entirely smooth. This composition is thought to develop from an initially entirely smooth muscle composition in the embryo, which slowly transdifferentiates into skeletal muscle during later embryological development.
The oesophagus is involved in the passage of food from the pharynx to the stomach, aided by peristaltic contractions. The upper oesophageal sphincter (UES) is a high-pressure zone situated between the pharynx and the cervical oesophagus, composed of all skeletal muscles. The lower oesophageal sphincter (LES), on the other hand, is composed of all smooth muscles and provides a strong sphincter mechanism at the lower end of the oesophagus.
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It is innervated by nerves and neurons
The oesophagus is a 20-25 cm long fibromuscular tube that connects the pharynx to the stomach. It is composed of muscles that run longitudinally and circularly, and it is a part of the digestive system. The oesophagus is innervated by both parasympathetic and sympathetic nerves. The parasympathetic nerves control peristalsis via the vagus nerve, which arises from the lower motor neurons in the nucleus retrofacialis and the compact formation of the nucleus ambiguus. The vagus nerve plays a primary role in initiating peristalsis, and it supplies the muscles of the oesophagus and stimulates glandular contraction.
The oesophagus is also innervated by voluntary nerves, or lower motor neurons, which are carried in the vagus nerve to innervate its striated muscle. The upper third of the oesophagus contains striated muscle, while the lower third contains smooth muscle. The cervical oesophagus has a myenteric plexus with a large number of neurons containing nitric oxide synthase (NOS). These neurons are thought to receive preganglionic input from the dorsal motor nucleus of the vagus (DMN). Nitric oxide may inhibit acetylcholine release from the motor end plates, and the physiologic role of these nitrergic neurons in the striated muscle portions of the oesophagus remains unknown.
The oesophagus is also innervated by spinal afferents, which have their cell bodies in the dorsal root ganglia and terminate in the spinal column and in the nucleus gracilis and cuneatus in the brainstem. These spinal afferents act as nociceptors for the perception of discomfort and pain and are mechanosensitive. They are also involved in mediating acid-induced pain during topical exposure to intraluminal acid. The neurophysiological basis of oesophageal pain and discomfort is not well understood, but functional disorders such as non-cardiac chest pain are thought to be associated with hypersensitivity of primary afferents innervating the oesophagus.
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The oesophagus can suffer from disorders such as ulceration and bleeding
The oesophagus is a muscular tube that connects the throat to the stomach. It is lined with a mucous membrane consisting of a stratified squamous epithelium, a lamina propria, and a muscularis mucosae. The oesophagus is made up of several layers, including the mucosa, muscularis mucosa, submucosa, and muscularis propria. The muscularis mucosa is a thin layer of muscle that extends through the entire oesophagus, while the muscularis propria is the dominant muscle layer, organised into inner circular and outer longitudinal muscle layers.
The oesophagus contains two types of muscles: smooth muscle and striated muscle. The upper third of the oesophagus contains striated muscle, the lower third contains smooth muscle, and the middle third contains a mixture of both. The smooth muscle is innervated by involuntary nerves, while the striated muscle is innervated by voluntary nerves. The vagus nerve plays a crucial role in initiating peristalsis and supplying the muscles of the oesophagus.
The oesophagus can suffer from various disorders, including ulceration and bleeding. Oesophageal ulcers are peptic ulcers that occur when the protective layer of mucus lining the gastrointestinal tract wears away, allowing stomach acid and gastric juices to irritate and damage the oesophageal mucosa. This prolonged exposure to gastric acid and bile salts can lead to necrosis and ulcer formation. Gastroesophageal reflux disease (GERD) is a common cause of oesophageal ulcers, and it can also be caused by infections, certain medications, and chronic consumption of acidic foods and drinks.
Oesophageal ulcers can cause symptoms such as burning pain in the centre of the chest and behind the sternum. Early intervention is crucial to prevent complications, and treatment options include medication (such as antacids, H-2-receptor blockers, and proton pump inhibitors), lifestyle and dietary changes, and surgery in severe cases. Untreated oesophageal ulcers can lead to bleeding, Barrett's oesophagus, strictures, and perforation. Therefore, prompt diagnosis and treatment by a medical professional are essential to manage and prevent complications from oesophageal disorders.
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Frequently asked questions
The esophagus is a hollow, muscular tube that carries food and liquid from the throat to the stomach.
The esophagus contains both smooth and striated muscle. The upper third of the esophagus contains striated muscle, the lower third contains smooth muscle, and the middle third contains a mixture of both.
The muscles in the esophagus propel food down to the stomach through peristalsis, which involves creating waves that actively push the contents down the digestive system. The muscles at the top and bottom of the esophagus also play an important role in preventing stomach acid and digestive juices from entering the esophagus.
Disorders of the esophageal muscles include gastroesophageal reflux disease (GERD), heartburn, achalasia, and spasms. These issues can cause symptoms such as chest pain, difficulty swallowing, and acid reflux.
