Azygos System, Trachea, and Broncho-pulmonary Segments Flashcards

Vocabulary flashcards for review.

Azygos System

A venous system that is straight in course and paravertebral in position and communicates with the venacava and vertebral venous plexus.

Formation of Azygos Vein

Formed by the union of the right ascending lumbar and right subcostal vein at the level of T12.

Azygos Vein Position

Passes upwards in front of the lower 8 thoracic vertebrae.

Termination of Azygos Vein

Arches forward at the level of T4 and opens into the superior vena cava.

Relations of Azygos Vein (Front)

Oesophagus, fibrous pericardium, left atrium, and root of right lung.

Relations of Azygos Vein (Behind)

Lower 8 vertebrae and posterior intercostal veins.

Relations of Azygos Vein (Right)

Splanchnic nerve, right lung, and pleura.

Relations of Azygos Vein (Left)

Thoracic duct, descending aorta, esophagus, right vagus, and trachea.

Azygos Vein Tributaries

Superior intercostal vein (formed by the 2nd, 3rd, and 4th veins), 5th to 11th posterior intercostal veins, subcostal vein, accessory hemi-azygos and hemiazygos veins.

Accessory Hemiazygos Vein

Drains the 5th, 6th, and 7th posterior intercostal veins and terminates into the azygos vein at the level of T7.

Hemiazygos Vein

Drains the 8th-11th veins separately and terminates into the azygos vein at the level of T8.

Development of Azygos Vein

Develops from two sources: the lower vertical part (right azygos venous line) and the arch of azygos (persistent cephalic part of right posterior cardinal vein).

Clinical Importance of Azygos Vein

Maintains collateral circulation by draining blood to the right atrium during obstruction of the superior or inferior vena cava.

Trachea

A membranocartilaginous tube that is a continuation of the larynx.

Beginning of Trachea

Lower border of the cricoid cartilage at the C6 vertebra.

Bifurcation of Trachea

Occurs at the sternal angle (T4).

Trachea in Newborns

Bifurcates at T3.

Structure of Trachea

C-shaped hyaline cartilage rings connected behind by the trachealis muscle.

First Tracheal Ring

The broadest ring.

Last Tracheal Ring

Presents a triangular process called the carina.

Number of Tracheal Rings

16-20 rings.

Lining of Trachea

Lined by pseudostratified ciliated columnar epithelium.

Right Principal Bronchus

More vertical, wider, and shorter compared to the left bronchus.

Divisions of Right Bronchus

Enters the hilum and divides into upper, middle, and lower lobe secondary bronchi.

Divisions of Secondary Bronchi

Each secondary bronchus divides into tertiary bronchi.

Left Principal Bronchus

Longer, narrower, and oblique compared to the right bronchus.

Divisions of Left Bronchus

Divides into upper and lower secondary bronchi.

Upper Lobar Bronchus

Divides into ascending and descending branches.

Broncho-pulmonary Segment

Area of lung aerated by a tertiary bronchus.

Intersegmental Septum

Each segment is separated by this.

Pulmonary Veins

Runs in intersegmental septum.

Pulmonary Artery

Follows tertiary bronchus.

Broncho-pulmonary Segments of Right Lung (Upper)

Apical, anterior, and posterior segments.

Broncho-pulmonary Segments of Right Lung (Middle)

Medial and lateral segments.

Broncho-pulmonary Segments of Right Lung (Lower)

Apical, medial basal, lateral basal, anterior basal, and posterior basal segments.

Broncho-pulmonary Segments of Left Lung (Upper)

Apical, anterior, posterior, superior lingular, and inferior lingular segments.

Broncho-pulmonary Segments of Left Lung (Lower)

Apical, medial basal, lateral basal, anterior basal, and posterior basal segments.

Breath Sound Auscultation

Breath sound more audible in right lung because, trachea is closer to right lung.

Foreign Body Aspiration

More common in the right lung due to the right principal bronchus being shorter, wider, and more vertical.

Carina

A triangular process at the bifurcation of the trachea.

Tracheostomy Indications

Prolonged ventilator dependence, prophylactic tracheostomy, obstructive sleep apnea, chronic aspiration, neuromuscular disease, subglottic stenosis, severe laryngeal edema.

Tracheostomy Contraindications

Cellulitis of the anterior neck, bleeding disorders.