Respiratory Tract and Trachea Overview

Respiratory Tract

• The respiratory tract is a network of passageways that supplies air to the lungs.
• The upper respiratory tract includes the nasal passages and sinuses, pharynx, larynx, and upper portion of the trachea.
• The lower respiratory tract includes the lower portion of the trachea, bronchi, and bronchioles.

Trachea

• The trachea is a mobile cartilaginous and membranous tube.
• It begins in the neck as the continuation of the larynx at the lower border of the cricoid cartilage.
• It ends by dividing into right and left principal bronchi at the level of the sternal angle.
• The trachea is approximately 4.5 inches long and 1 inch in diameter in adults.
• The trachea is supported by U-shaped bars of hyaline cartilage called tracheal rings.
• The trachealis muscle connects the posterior free ends of the cartilages.

Trachea Blood Supply

• The inferior thyroid arteries supply the upper two-thirds of the trachea.
• The bronchial arteries supply the lower third of the trachea

Trachea Lymph Drainage

• Lymph drainage occurs in the pretracheal and paratracheal lymph nodes.
• Lymph also drains to deep cervical nodes.

Trachea Nerve Supply

• The vagus and recurrent laryngeal nerves carry the sensory nerve supply.
• Sympathetic nerves supply the trachealis muscle.

Tracheostomy

• Tracheostomy is a procedure where a hole is made through the front of the neck and into the trachea.
• A tube is placed into the hole to keep it open for breathing.
• Tracheostomy is performed when the usual route for breathing is blocked.

Compression of the Trachea

• Enlargement of the thyroid gland can cause displacement or compression of the trachea.
• Aortic arch dilatation can compress the trachea.
• An aneurysm can tug at the trachea and left bronchus.

Tracheitis and Bronchitis

• The recurrent laryngeal nerves innervate the mucosa lining much of the trachea.
• Tracheitis or bronchitis can cause a raw, burning sensation felt deep to the sternum.

Esophagus

• The esophagus is a muscular tube that connects the pharynx to the stomach.
• The esophagus has three parts: cervical, thoracic and abdominal.
• The cervical part begins at the level of the cricoid cartilage and descends in front of the vertebral column.
• The thoracic part runs through the superior mediastinum and ends at the diaphragm.
• The abdominal part is the shortest part and connects to the stomach.

Esophagus Relations

• The esophagus is related to the trachea, thyroid gland, aorta, left primary bronchus, and diaphragm.
• The esophagus is in contact with the trachea in the neck.

Esophagus Blood Supply

• The esophagus is supplied by branches of the inferior thyroid arteries, bronchial arteries, and left gastric artery.
• The inferior thyroid arteries supply the upper part.
• The bronchial arteries supply the middle part.
• The left gastric artery supplies the lower part.

Esophagus Lymphatics

• The upper part of the esophagus drains into the deep cervical nodes.
• The middle part of the esophagus drains into the superior and posterior mediastinal nodes.
• The lower part of the esophagus drains into nodes along the left gastric blood vessels and the celiac nodes.

Esophageal Atresia & Tracheoesophageal Fistula

• Esophageal atresia and tracheoesophageal fistula are common in infants.
• Type A: There is a blind pouch at the proximal end of the esophagus and a fistula connecting the trachea to the distal esophagus.
• Type B: The proximal and distal esophagus are connected by fibrous tissue but there is no patent connection.
• Type C: There is a complete blockage of the esophagus.
• Type D: There is slow passage of milk through the esophagus.
• Type E: The milk enters the trachea and lungs.
• Type F: The milk enters the lungs and air enters the stomach
• Type G: The milk is vomited.

Esophagus Constrictions

• Esophagus has three constrictions.
• The first constriction is at the cricopharyngeal muscle.
• The second constriction is where the aortic arch and the left primary bronchus cross its anterior surface.
• The third constriction is where the esophagus passes through the diaphragm.
• Constrictions can cause difficulty passing an esophagoscope or foreign body impaction.

Importance of Esophagus Constrictions

• These are the sites where swallowed foreign bodies can lodge or through which it may be difficult to pass an esophagoscope.
• Due to the common occurrence of foreign body impaction within the esophagus, it is often considered a point of interest in endoscopic procedures wherein a scope will be inserted inside the mouth through the pharynx into the esophagus.

Considerations

• The esophagus is vulnerable to gastroesophageal reflux disease (GERD) and hiatal hernias.
• A weakened esophageal sphincter can cause acid reflux which can lead to complications such as Barrett's esophagus and an increased risk of esophageal cancer.

This quiz covers the anatomy and function of the respiratory tract, specifically focusing on the trachea. Learn about the structures involved, their blood supply, and the distinctions between the upper and lower respiratory tracts. Test your knowledge on this essential part of human physiology.