Trachea and Esophagus Anatomy PDF

Left side: The arch of the aorta, the left common ANATOMY carotid and left subclavian arteries, the left vagus and left phrenic nerves, and the pleura FIN...

Left side: The arch of the aorta, the left common ANATOMY carotid and left subclavian arteries, the left vagus and left phrenic nerves, and the pleura FINALS: Thoracic Cavity II (Esophagus & Trachea) TRACHEA RESPIRATORY TRACT (TREE) - network of passageways that supplies air to the lungs Upper respiratory tract - nasal passages and sinuses, pharynx, larynx, and upper portion of the trachea Lower respiratory tract - lower portion of the trachea, bronchi, and bronchioles Trachea: BLOOD SUPPLY - a mobile cartilaginous and membranous tube Inferior thyroid arteries (branches of the subclavian - It begins in the neck as the continuation of the larynx arteries) supply the upper two thirds of the trachea at the lower border of the cricoid cartilage at the level Bronchial arteries (branches of the thoracic aorta) of the sixth cervical vertebra. supply the lower third. - It descends in the midline of the neck. - In the thorax, the trachea runs through the superior mediastinum, in approximately the midline. LYMPH DRAINAGE - It ends by dividing into right and left principal (main) pretracheal and paratracheal lymph nodes bronchi at the level of the sternal angle (opposite deep cervical nodes. the disc between the fourth and fifth thoracic vertebrae). NERVE SUPPLY - During expiration, the bifurcation rises by about one The vagus and recurrent laryngeal nerves carry the vertebral level and during deep inspiration may sensory nerve supply. lower as far as the sixth thoracic vertebra. Sympathetic nerves supply the trachealis muscle. - In adults: → 4.5 in. (11.25-cm) long → 1 in. (2.5 cm) in diameter. CLINICAL NOTES TRACHEOSTOMY - A hole surgeons make through the front of the neck and into the trachea. A tube is placed into the hole to keep it open for breathing. - Provides an air passage to help breathe when the usual route for breathing is blocked or reduced. - It is often needed when health problems require long-term use of a ventilator to help in breathing. - In rare cases, an emergency tracheostomy is performed when the airway is suddenly blocked, such U-shaped bars (tracheal rings) of hyaline cartilage as after a traumatic injury to the face or neck. embedded in the tracheal wall support and maintain - When tracheostomy is no longer needed, it is allowed the patency of the trachea (16-20 rings) to heal shut or surgically closed. For some people, Trachealis muscle (a smooth muscle) connects the tracheostomy is permanent. posterior free ends of the cartilages. - The posterior discontinuity permits the esophagus COMPRESSION OF THE TRACHEA to expand into the trachea during swallowing. - In the neck, a unilateral or bilateral enlargement of the thyroid gland can cause gross displacement or The relations of the trachea in the superior mediastinum of the compression of the trachea. thorax are as follows: - A dilatation of the aortic arch (e.g., an aneurysm) Anteriorly: The sternum, the thymus, the left can compress the trachea. brachiocephalic vein, the origins of the - With each cardiac systole, the pulsating aneurysm brachiocephalic and left common carotid arteries, and may tug at the trachea and left bronchus, a clinical the arch of the aorta sign that can be felt by palpating the trachea in the Posteriorly: The esophagus and the left recurrent suprasternal notch. laryngeal nerve Right side: The azygos vein, the right vagus nerve, and the pleura JBD 1  vertebrae. Lies behind the trachea in the superior TRACHEITIS / BRONCHITIS mediastinum. From the bifurcation of the trachea - The recurrent laryngeal nerves innervate the downwards, the esophagus then passes behind mucosa lining much of the trachea. the right pulmonary artery - A tracheitis or bronchitis gives rise to a raw, burning 3. Abdominal Part: Enters abdomen by passing sensation felt deep to the sternum instead of actual through the opening in the diaphragm (T10). About pain. 2 cm (in the abdomen): esophagus opens in the - Many thoracic and abdominal viscera, when cardiac end of the stomach diseased, give rise to discomfort that is felt in the midline. - It seems that organs possessing a sensory IN THE NECK innervation that is not under normal conditions directly the esophagus lies in the front of the vertebral relayed to consciousness display this phenomenon. column - The afferent fibers from these organs traveling to the laterally: related to the lobes of the thyroid gland central nervous system accompany autonomic anteriorly: it is in contact with the trachea and the nerves. recurrent laryngeal nerves IN THE THORAX ESOPHAGUS it passes downward and to the left through the ➔ a tubular structure about 10-in. (25-cm) long that is superior and then the posterior mediastinum continuous above with the laryngeal part of the At the level of the sternal angle, the aortic arch pharynx opposite the sixth cervical vertebra. pushes the esophagus over to the midline ➔ It passes through the esophageal hiatus of the diaphragm at the level of the 10th thoracic vertebra IN THE ABDOMEN to join the stomach The esophagus descends for about 0.5 in. (1.3 cm) and then enters the stomach. SWALLOWING/ DEGLUTITION- Anteriorly: left lobe of the liver anteriorly process of moving food from mouth Posteriorly left crus of diaphragm to the stomach STEPS: 1. Mastication (chewing)- food is broken down into smaller pieces by the teeth and the saliva will moisten the food to form a soft mass (bolus). 2. Swallowing (pharyngeal stage)- the tongue pushes blus to the back of the mouth which triggers the The relations of the thoracic part of the esophagus from above swallowing reflex. The epiglottis will then cover the trachea to prevent the food downward are as follows: from entering the lungs. 3. After swallowing, the upper esophageal sphincter (ring Anteriorly: of muscle at the top of esophagus) relaxes to allow the The trachea and the left recurrent laryngeal nerve; food bolus to enter the esophagus from the pharynx. left principal bronchus, which constricts it; 4. Peristalsis- The muscles of the esophagus then creates pericardium, which separates the esophagus from the peristalsis together with gravity to push the bolus left atrium downwards. Posteriorly: 5. When the bolus reaches the lower end of the esophagus, the lower esophageal sphincter will relax to allow the The bodies of the thoracic vertebrae, the thoracic bolus to pass and enter the stomach. Then the lower duct, the azygos veins, the right posterior intercostal esophageal sphincter will then close to prevent the arteries, and, at its lower end, the descending thoracic stomach contents from refluxing back into the esophagus. aorta Right side: The mediastinal pleura and the terminal part of the 3 DIVISIONS OF ESOPHAGUS azygos vein Left side: 1. Cervical Part: behind the Left subclavian artery trachea and in front of the Aortic arch, bodies of cervical vertebrae Thoracic duct 2. Thoracic Part: through the Mediastinal pleura superior and then the posterior mediastinum in front of the thoracic JBD 2 BLOOD SUPPLY Inferior thyroid artery - supplies the upper third of CLINICAL NOTES the esophagus Esophageal branches from the descending ESOPHAGEAL CONSTRICTIONS thoracic aorta - middle third Branches from Left Gastric Artery - lower third 3 Anatomic and Physiologic Constrictions: 1. Where the pharynx joins the upper end of the Venous Drainage esophagus. Caused by the cricopharyngeal muscle. upper third drain into the inferior thyroid veins, Narrowest point of the esophagus (6 in./15 cm from middle third into the azygos veins the upper incisor teeth). lower third into the left gastric vein, a tributary of the Common site for food bolus obstruction. Usually happens to patients portal vein. with swallowing disorders (neuromuscular disorders, elderly). Can also be a point of interest in endoscopic procedures wherein a scope will be inserted inside the mouth through the pharynx then to the esophagus. Sometimes, the scope will be dislodged or stucked because of the constriction, and as a marker of the 1st esophageal constriction. 2. Where the aortic arch and the left primary bronchus cross its anterior surface (10 in./ 25 cm from the incisor teeth). Common site for foreign body impaction and can be challenging during esophageal stent placement or balloon dilations. 3. Where the esophagus passes through the diaphragm into the stomach (16 in./ 41 cm from the incisor teeth). LYMPH DRAINAGE Associated with GERD and hiatal hernias. Weakened esophageal Upper third of the esophagus drain into the deep sphincter can cause acid reflux (chronically, can contribute to cervical nodes complications like Barrett’s esophagus, and eventually increase the Middle third into the superior and posterior risk of esophageal cancer.) mediastinal nodes Lower third into nodes along the left gastric blood Importance: vessels and the celiac nodes These are the sites where swallowed foreign bodies can lodge or through which it may be difficult to pass an esophagoscope. Because a slight delay in the passage of food or fluid occurs at these levels, strictures (narrowings) may develop here after drinking caustic fluids. These constrictions are also the common sites of carcinoma of the esophagus. NERVE SUPPLY supplied by parasympathetic and sympathetic PORTAL-SYSTEMIC VENOUS ANASTOMOSIS fibers via the vagi and sympathetic trunks, → at the lower third of the esophagus respectively. → “Porto-Systemic Shunts” (3): crucial in clinical practice, In the lower part of its thoracic course, the esophagus usually in patients with portal hypertension. Provides alternate is surrounded by the esophageal nerve plexus. pathways for blood to bypass the liver when there is increase pressure in the portal venous system which can usually occur in patients who have liver cirrhosis. → Esophageal tributaries of the azygos veins (systemic veins) anastomose with the esophageal tributaries of the left gastric vein (components of the hepatic portal system). Should the portal vein become obstructed (e.g., in cirrhosis of the liver), portal hypertension develops, JBD 3  resulting in dilatation and varicosity of the portal–systemic anastomoses. Varicose esophageal veins may rupture during the passage of food, causing hematemesis (vomiting of blood), which may be fatal. ESOPHAGEAL ATRESIA & TRACHEOESOPHAGEAL FISTULA (COMMON IN INFANTS/NEWBORN) PSV Anastomosis Type A. The proximal esophagus ends up in a blind pouch. There is a fistula (canal). When a newborn drinks milk, the milk will just end up in the blind pouch, as a result, the infant will just vomit the milk. When the infant will cry, the air will not only go to the lungs, but also to the stomach since there is a connection from the trachea to the distal esophagus via the fistula. Infants with TEF present a bloated abdomen. Type B. There is no actual patent connection, but only conjoined by a fibrous tissue Type C. Complete blockage Type D. When the infant will drink milk, the infant will also vomit because there is slow passage of the milk through the esophagus. Type E. When the infant drinks milk, the milk will go directly into the trachea, then into the lungs. Ultimately, the infant will aspirate, just like introducing fluid into the lungs of the patient. Type F. The milk will enter the lungs, at the same time, the air will enter the stomach Type G. The milk will just be vomited. Type A and B occur more frequently Intervention: surgical JBD 4 JBD 5