The esophagus, the topography of which will be discussed later, is a fibrous tube about 25 cm long that transports food from the pharynx to the stomach. It extends to the heart hole of the stomach. Consider the anatomy of the esophagus: its structure, vascular supply and clinical correlation.
Anatomical location
The esophagus, topography, structure, the blood supply of which is examined, begins in the neck at the level of the sixth cervical vertebra. It is inextricably linked with the laryngeal part of the pharynx, and descends down into the upper mediastinum of the chest. Here, this organ is located between the trachea and vertebrae. Then it enters the abdominal cavity, punching the muscular right cross of the diaphragm through a break (just a hole in the diaphragm).
Features of the anatomical structure
The topography of the human esophagus is represented by the phrenodophagous ligament, which connects it to other organs. This allows you to independently move the organ and diaphragm during breathing and swallowing.
The abdominal part of this part of the body is approximately 2 cm long - it ends with accession to the stomach.
Muscle layers
The esophagus, the topography of which is being studied, consists of an internal circular and external longitudinal layer of muscles. In addition, the outer longitudinal layer consists of different types of muscles in each third of the organ:
- The highest third is the striatus muscle;
- The middle third is a striped and smooth muscle;
- The lower third is smooth muscle.
Food is transported by peristalsis - rhythmic contractions of the muscles that extend along the entire length of the organ. Strengthening these muscle layers can inhibit peristalsis and cause dysphagia - difficulty swallowing.
Anatomical relationships
The organ is close to many structures in the chest and abdomen:
- trachea;
- left recurrent laryngeal nerve;
- pericardium;
- vertebral bodies;
- thoracic canal;
- aortic lowering;
- pleura;
- terminal part;
- subclavation artery;
- aortic arch;
- abdominal part;
- left vagus nerve;
- back surface of the heart;
- right vagus nerve;
- left slit of the diaphragm;
- esophageal sphincters.
Two sphincters are present in this part of the body: the upper and lower. They provide prevention of air intake and reflux of the contents of the stomach, respectively.
Upper Esophageal Sphincter
The topography of the esophagus (cervical) is represented by the superior sphincter. This is an anatomical striated muscle sphincter at the junction between the pharynx. It is usually narrowed to prevent air from entering.
Lower sphincter
Also includes the topography and structure of the esophagus, the digestive tract - the lower sphincter. This is a physiological sphincter located in the gastroesophageal junction (the connection between the stomach and esophagus). The gastroesophageal junction is located to the left of the vertebra and is marked by a change to the gastric mucosa.
The sphincter is classified as physiological (or functional), since it does not have any specific muscle. Instead, he:
- enters the stomach at an acute angle;
- the walls of the intra-abdominal department are compressed in the presence of positive intra-abdominal pressure;
- folds of the mucous membrane help with occlusion of the lumen on the gastric junction.
During peristalsis, the sphincter is relaxed so that food enters the stomach. Otherwise, at rest, the function of this sphincter is to prevent reflux of the acidic contents of the stomach.
Vascular network
As for arterial and venous supply, the esophagus can be divided into its thoracic and abdominal sections.
The thoracic part of the esophagus receives arterial nutrition from the branches of the thoracic aorta and the lower thyroid artery (trunk branch). Venous drainage into the systemic circulation occurs through the branches of the azigous veins and the lower thyroid vein.
The abdominal stomach is supplied with the left gastric artery (branch of the abdominal cavity) and the left lower diaphragm. This part of the esophagus has mixed venous drainage in two ways:
- to portal blood circulation through the left gastric vein;
- to systemic circulation through the aziginous vein.
These two routes form the connection between the portal and venous systems.
Lymphatic drainage of the esophagus is divided into thirds - deep cervical lymph nodes. The upper and posterior third are mediastinal nodes. The lower third is the left gastric and celiac nodes.
Clinical relevance
Esophageal disorders are metaplasia. This is a reversible change from one differentiated cell type to another. It touches the lower esophageal squamous epithelium and continues into the gastric columnar epithelium. Typically, the phenomenon is caused by chronic exposure to acid as a result of disruption of the lower esophageal sphincter.
Acid irritates the epithelium of the esophagus, which leads to a metaplastic change. The most common symptom is a long-term burning sensation in digestive disorders. It can be detected by endoscopy of the esophagus. Patients with such a change will be under the supervision of specialists.
Esophageal carcinoma
About 2% of malignant neoplasms are esophageal carcinomas. The clinical features of this carcinoma are dysphagia - difficulty swallowing. Over time, the tumor becomes larger, as it grows in size, restricting the passage of food.
Mass loss
There are two main types of esophageal carcinoma:
- squamous cell carcinoma;
- adenocarcinoma.
Malignant cell carcinoma is the most common type of cancer of the esophagus. This can happen at any level of the esophagus. Adenocarcinoma occurs only in the lower third of the esophagus and is associated with Barrett's esophagus. This usually occurs in the metaplastic epithelium of Barrett's esophagus.
The abdominal esophagus merges into the systemic and portal circulation, forming an anastomosis. Varicose veins are abnormally dilated submucous veins (in the wall of the esophagus) that lie within this anastomosis. They usually appear when the pressure in the system goes beyond the normal state known as portal hypertension. Portal hypertension is most often found secondary to chronic liver diseases such as cirrhosis or obstruction in the portal vein.
Varicose veins are prone to bleeding, with most patients with hematemia suffering from vomiting of blood. Alcoholics are at high risk for developing varicose veins of the esophagus.
Animals: features of this organ
The topography of the esophagus in animals is relatively unusual. The study of the structure is based on the medical history and clinical signs of the malaise of the animal. Esophagitis and acquired diseases of the esophagus are caused by prolonged contact of caustic substances or foreign bodies with the esophageal lining, which leads to trauma to the mucous membrane. In cases of stress, damage extends to the submucosal and muscle layers.
The timely detection and proper management of esophagitis and angina pectoris of the esophagus significantly improves the nutritional status, dysphagia and pain and often returns the animal to a normal quality of life.
The esophagus, the topography of which must be carefully studied, is characterized by diseases in the animal, which cause a number of clinical signs, including regurgitation, weight loss and respiratory distress. The diagnosis of esophagitis is complex and often requires specialized procedures such as endoscopy. If inflammation damages the submucosal and muscle tissue, a scar can develop, which leads to obstruction of the lumen of the esophagus and a more serious illness.
Nevertheless, significant success has been achieved in the treatment of esophagitis of the esophagus, the topography of which today requires more in-depth research. With proper treatment of esophageal diseases, veterinary patients can have a significant improvement in clinical signs and a return to normal.
Normal anatomy and physiology
The esophagus consists of three layers: the mucosa, submucosa, and muscle. The mucous membrane is lined with squamous epithelium and overlaps the submucous membrane. In dogs, the muscle layer consists entirely of skeletal muscle, in cats, the distal third is smooth muscle. There is no serous layer in the esophagus; instead, it is covered by adventitia.
The esophagus has an upper and lower sphincter. The upper sphincter of the esophagus consists of muscles. The lower esophageal sphincter or LES (LES) consists of the muscle layers around the esophagus and the diaphragmatic region.
It is believed that these layers create a pressure barrier that prevents reflux of the contents of the stomach into the esophagus. FOREST relaxes during swallowing to allow food to enter the stomach. It has been suggested that the location of the LES may play a role in the occurrence of reflux. Theoretically, LES prevents reflux, because positive pressure in the stomach increases the strength of the esophagus compared to the stomach and increases the barrier pressure.
Therefore, in some people who do not have an abdominal esophageal component, there is a tendency to primary gastroesophageal reflux disease. However, a recent study of greyhounds and beagles has shown that dogs change depending on whether the position of the gastroesophageal junction is intrathoracic or intra-abdominal. This finding implies that intra-abdominal LES may not be necessary to prevent reflux in dogs.
When an ingesta bolus reaches the caudal pharynx, afferent sensory fibers stimulate the swallowing center in the brain. Breathing is temporarily blocked, while efferent motor fibers stimulate the esophagus through the vagus nerve, causing primary peristalsis to transport ingesta. Secondary peristalsis is similar to primary peristalsis, except that the impulse is initiated by stretching the esophagus. The innervation of the esophagus, the topography and structure of which were discussed above, is mainly parasympathetic with respect to the vagus nerve. When food approaches the stomach, the transmission of sensory information leads to relaxation of the forest.
Topography and anatomy of the esophagus have been studied by many experts. Normal physiological protection against inflammation of the esophagus is FOREST, the mucous membrane of the esophagus, the clearance of the esophagus through motility, the neutralizing effect of alkaline saliva and the circulation of esophageal cells. Esophagitis is defined as inflammation and violation of the mucous membrane of the esophagus with the resulting effect of the submucous membrane of the esophagus. Causes of esophagitis include gastroesophageal reflux, vomiting, and ingestion of foreign bodies, caustic substances, or drugs. Gastroesophageal reflux caused by anesthesia is the most common cause in veterinary literature. 2-6
In animals, inflammation of the esophagus, whose topography, structure and structure are important, is often affected by diseases. Usually the esophagus cleans most of the refluxate with primary and secondary peristaltic waves, and the bicarbonate present in the salivary secretions neutralizes any residual reflux.
To summarize
The esophagus, the structure and topography of which were considered in the article, is often exposed to diseases. For their successful treatment, it is necessary to know exactly the features of this system.